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A little distance and room make a difference.

 

Gold Member
Username: Superjazzyjames

Post Number: 1067
Registered: Oct-10
For about the past 2 yrs, I've had to have the bass on my receiver at -10 (db? so they claim) because my subwoofer, at 8" & 100 watts is a beast and it's in a room that reinforces bass. Add to that, it had to be closer to the walls than it should be so that it wouldn't become a tripping hazard and was flanked by a wooden cabinet on one side.

Thursnite, I found a way to arrange the room so that the cabinet could be moved away from the sub and the sub could be safely moved 6" further away from one wall and a foot further from the other wall. This allowed me to set the tone controls flat like I prefer to have them. The overall sound benefits from this arrangement too.
 

Gold Member
Username: Magfan

USA

Post Number: 1958
Registered: Oct-07
Super, if your listening area is not some odd shape, go to google and try 'room mode calculator'.
You'll get a readout of various room modes....2, 3, or 4 wall bounces and the 'cogging' frequencies they generate.
It is very unusual for bass response to be uniform thruout a normal sized listening space.
The tuneup you did was all for the good.

My room? 8 asymmetric sides and a vaulted ceiling. I am very lucky in this regard, since the bass is pretty uniform at all normal seating positions. My den, off to one side has a bass 'bump' in it which renders music thumpy.

My sub is in the same plane as my panels, maybe 3' from the 'front' wall and about a foot from the nearest side wall. Moving the sub harder into the corner muddies things up.
 

Gold Member
Username: Superjazzyjames

Post Number: 1078
Registered: Oct-10
Thanks Leo, I wasn't sure I wanted to rearrange things right now since I plan to move in March. However, there was a nagging curiosity. Once moved, I'll have more room to work with and spend more time on possible arrangements. Hopefully the new music room won't reinforce the bass quite as much.

The new arrangement certainly is all for the better. The crossover point is still 40 Hz which I find a little odd only because the omnis start rolling off at 70 Hz. I thought somewhere in the 60 to 70 Hz range would work better, but anything above 40 overlaps too much.

The octogon room must be nice. Sounds like you could have a lot of fun trying out different set ups.
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 3029
Registered: Dec-06
I can tell you that I seem to have the opposite of your problem. I had a pair of JBL 4311 studio monitors in my room several years ago (75w nominal rating) driven with a good quality 100w RMS receiver and I had no issues. The response was solid to 45hz (and 40hz was okay) and really gave me some great times with my usual choice of music at the time - alternative (like Coldplay) and some oldies and then random songs on the radio. Then I got some used speakers (garage sale) and decided to set up a home theater arrangement in another room. When I first fired it all up (new receiver as well, but I'll get to that in a bit) all excited, I was shocked to hear a thin lifeless "cardboard" sound (as in anemic bass) coming from the system, especially considering that the speakers use 12" drivers.

I just 'dealt with it' for a while and ended up trying to fix the problem with a Paradigm UltraCube 10 subwoofer, which is funny seeing that the driver in the subwoofer was smaller than in the main and surround speakers, although it had twice the amplifier power of all of the speakers put together. It helped and I thought it sounded pretty good, but it didn't hold up at higher volumes. It was useless for movies. There was always an issue of my ears getting a weird feeling as if the bass was coming from the direction of the subwoofer (it was crossed at 60hz) which was really distracting. One day while playing some music, I managed to blow the driver. I had several people exclaim at how impossible it is to blow that subwoofer with the heavy protection it has, meaning I really had to be stressing it if I blew it.

After returning it, I saved up a bit and got a high-quality receiver with a suspicion of the now aging receiver that had been driving the speakers. It was a huge difference, drastically improving the low part of the spectrum, but it was nowhere near what I had in the original room. To this day, driving the speakers without a subwoofer to aid them, even when driven with very high levels of bass from the very capable amplifier, gives thin sound that lacks impact.

After all of the frustration, years later I built a large cylinder sub using an 18" driver driven by an amplifier tested at 1800w RMS 20hz. Even after loads and loads of tweaking, EQing, and experimenting, something is not quite right, and the output is still lacking quite a bit. The actual driver seems to be very good. I have checked everything from phase to enclosure Q characteristics to EQ to 9 different room placements to ground plane SPL measurements. After all of the testing, I have concluded that my room and positioning are partially to blame, as well as possible issues with subwoofer construction causing output issues (measuring 84dB sensitivity in upper range and dropping a bit towards the low end), The other problem is that none of these issues can be tackled/tested without a lot of time and effort. These may be testing the sub in a different configuration (enclosure type and size), testing the sub in a different room, or re-arranging my setup and furniture for the best sound. Then there is the brute force approach of a second subwoofer to subdue those room modes and maybe relieve the directionality phenomenon.

To add, the UltraCube 10 was in my room where I had good sound originally and it was intense and great in there for about 15 minutes before I moved it into the room having all of the issues.

Sooo.... pointlessly long story short, at least you're not having problems of the opposite nature.
 

Gold Member
Username: Superjazzyjames

Post Number: 1099
Registered: Oct-10
That's weird Andre. It might be necessary to drop the crossover frequency, maybe as low as 40 Hz! Don't be afraid to try things that don't SEEM right. Theoretically, 40 Hz seems wrong for my system, but it's perfect.

It sounds like your room absorbs bass. You may have to put your speakers and sub very close to, if not touching the walls. Normally, this would be a very bad idea since the bass would be overwehlming. In this case however, it might be the solution. If you know someone local who is good, that person might be able to help you arrange the speakers & sub in order to overcome you bass issues. I once helped a young man down the street. The whole story is rather amuzing. I'm saving that for just the right time.

Don't be surprised at your subwoofer either. Mine has a 8" driver and I have used it with floor speakers with 12" woofers and it helped them tremendously. I know a guy who uses a 240 wpc amp to power his 15" Cerwin Vegas and his Yamaha 50 watt, 10" sub holds its own just fine. The rated output wattage of an amp says veru little about how loud a system can get. The 84 db rating of the sub on the other hand, says that the sub is not going to ever get very loud. You should see about getting one with a 90 db rating or better.
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 3031
Registered: Dec-06
I can only cross down to 50hz, which is where I have always tended to cross my speakers to the sub. I've certainly tried some odd things.

Yes. My room has 3 outside walls (drywall and brick construction), a large window (10 feet tall 6 feet wide) right next to the sub, a floor over a crawl space, a high vaulted ceiling, and a large open floor plan to the rest of the house.

As for someone to help, I'm pretty sure it wouldn't do any good in terms of knowledge of what to do, but it might help in the sense that I'd have an extra set of ears. Even then, I can pretty easily repeat something over and over while walking around observing room effects.

The thing is, my sub isn't "rated" at 84dB. It's rated at 90, models at 90 (ground plane, which is how I tested it), and tests at 84. At the time, it was tuned to something like 13-14hz and I have since then modified the tuning to ~17.5hz which may have affected the response a bit, but likely not any further than adding a few dB in the range of 17-35hz.

I use a parametric equalizer to control the response a bit, but I think I've finalized the thought that I have null issues at my listening position. When doing frequency tone tests, I can hear the effects of the tones being played at some frequencies (where things are rattling), but don't hear the bass I would expect. 30hz is an offender here. As the frequency gets down to 20-25hz, it becomes more of a presence of depth, then below that it becomes a bit spooky. 14hz causes some parts of the house to resonate. I've minimized rattling.

The placement is currently in the middle of a side wall, I've tried it in the corner, which does help on output a good amount (and the response is also good), but the tile flooring in the corner rattles horribly and is really loud. The rest of the corners have bad room modes.

I am considering trying a new arrangement, but like I said before, a lot of work in order to try that. I need to at least mathematically confirm success before trying anything like that.
 

Gold Member
Username: Superjazzyjames

Post Number: 1109
Registered: Oct-10
Well, keep us posted ok? Meanwhile, I'll see if I can come up with anything else.

 

Gold Member
Username: Magfan

USA

Post Number: 1968
Registered: Oct-07
Andre,
You are on wood / joist / crawlspace flooring? Man, that's just askin' for it.
Play some music and go 'downstairs'...maybe after the weather lets up a little and listen. I'll bet the bass 'downstairs' is awesome.

JBL 4311? My brother had a set of those powered by an SAE amp of about 100x2. Fine speaker, especially used as a 'studio monitor' which was a good use for them. I had them as the fronts in a dynaquad setup ran by its own amp. The backs? A pair of RSL copies of the 4311s. SoCal had a small stereo store and made there own speakers. My 3600s were a good copy and sounded wonderful for quite a bit less than the JBLs.....
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 3033
Registered: Dec-06
Now I feel like I've taken over the thread, but I suppose it does resonate with the original topic, and you obviously don't seem to mind.

I can't go to the crawl space right now (for the reasons you mentioned), but that is something I'd like to try to see what happens. The 4311s are approaching 40 now and it seems that they're starting to get worn out, but as surround speakers, it's not as big of a deal. I'm not sure it'd be worth restoring them. They're neat to have though, seeing as they provided my first REAL audio moment in 1999 when I was 6 or 7 and Good Vibrations was playing on a Saturday morning when I was about to leave. I had other moments and vague memories before then, but I wasn't able to comprehend it yet.

Enough of that...

I had all of the information already, but tonight I managed to make a realization after playing test tones at around a 20 watt (-20dB relative to full amplifier output) level and walking around making observations.

14-20hz: The various spots around the room had a rather even amount of 'presence' throughout this range and there were no nulls or peaks observed. I did observe a dizzying presence of energy on the other end of the house where the energy tends to build up. A cup with a drink in it had strong ripples reverberating on the surface.

20-28hz: Here's where some issues started to come up. The wall opposite of the subwoofer resonates badly when there is 21-23.5hz energy present, and it causes some peaks and nulls throughout. My listening position (LP when referred to again) loses a few dB here when EQ is off. Then there are file cabinets in the room which have resonation issues (I tamed them the best I could at the time when the subwoofer was first powered up) in the area of 23-27hz, and this has the same effect on my LP as before, but EQ can subdue the issue here well enough. 27-28hz causes the wall adjacent to the subwoofer to resonate, causing more of the same issue.

29-40hz: AHHH HA!!! This is where the major issues are. The longest dimensions of the listening space start to cause the real issues here. In the lower frequencies, the problems are caused by sympathetic vibration more so than the actual standing waves that occur because of room dimensions in my room. 29-34hz cause a lot of rattling at the LP, but I don't hear any actual true deep bass whatsoever, no matter how hard I drive the subwoofer. Even with -3dB drive levels (i.e. 1000w), I have no real bass at the LP, although everything around is vibrating and jumping all over the place - a true null at the LP. Then you have the 35-40hz range, which seems to suffer the same problems, but I don't think it's for the same reasons. It's not a true full-out null, because there is a little bit of bass at LP.

40hz-50hz: My LP still has some issues here, but EQ CAN tame it.

50hz+: Since 50hz is the crossover point, I have 3 bass sources in stereo mode here and because of this I don't have any real issues in this range. Theoretically 54hz-60hz should have some issues due to room dimensions, and this frequency range DOES have issues when I run each driver by itself. Even with stereo bass (i.e. left or right channel only, and not both), I'll always have at least two sources, so no issues here.

100-200hz: Here I have some issues, but EQ has subdued these as well.


I know I have a knack for writing a lot with questionable benefit. I wrote all of it in case someone sees something that I don't. I noticed these issues with the Paradigm subwoofer I owned before, also, except I didn't particularly realize what was happening. I only realize it now when I look back at the memories.



Sooo.... Looooonnng story short, I finally put together definitively that my LP is a null and I need to find a solution. The following are in order of difficulty to execute:

Solution 1: Move the subwoofer to find the best spot. Although I've done this before, I was less experienced with it, had a different tuning, and had 3-4% of the amplifier power I have now (tuning/power combined means maybe 20dB (100x) more energy to work with). I've also reorganized the room a bit to get more space, meaning more positions to try.

Solution 2: Move the listening position (as well as the subwoofer) as necessary. If I find that moving the subwoofer (easier than re-orienting the whole room) does not cure the nulls, then the next step is to move into an orientation that is more conducive to a workable response.

Solution 3: Haha. This would be moving into a different room altogether for a new set of problems that may be more workable. This is almost the same as #2 in difficulty, but my house layout makes it difficult to do this. This would be the next step if I could not do solution 4.

Solution 4: This would be adding more subwoofers. It may be all I need to use a dual or quad subwoofer setup that will override room mode issues, but the limitation here is time and money. A second equivalent subwoofer would cost $300 minimum to piece together (I already have everything needed, save for the driver and wood). As for 4 subs, that's out of the question for now.

SOLUTION X: There are several more solutions, I am sure. If anyone has any ideas, I can listen.

All of this is in that quest for the massive wow factor when the orchestral drums start pounding, the depth charges fly, the kick drum starts pounding, that shock wave rips across the room/screen, and so on. The most euphoric audio experiences I've had were largely due to great bass.

I know I write really long posts. Any help is appreciated.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 15684
Registered: May-04
.

"I know I write really long posts. Any help is appreciated."


Edit.







.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 15685
Registered: May-04
.

Andre, you've never once mentioned any sort of room treatment devices. Until you do something with the room, it doesn't matter how many drivers you put in the space trying to minimize room nodes, the room will fight you and it will win. You have to go about this logically and IMO all you've done so far is go about getting the largest amplifier and the biggest driver and enclosure you could find. When the screw doesn't fit the hole, getting a bigger hammer isn't the solution. You can solve some of your problems with placement but the room still has the same dimensions no matter where you and the subwoofer sit.


Items in the room resonate at harmonic frequencies of the fundamental or of other harmonics. A tea cup full of liquid is not likely to have a resonant frequency between 14-20Hz. It is likely to have a resonant frequency at some upper harmonic of those frequencies. Which means just because your spec sheet told you the driver/enclosure could produce 14Hz, the tea cup's resonance doesn't prove that it is capable of doing so inside your room.

EQ is seldom the solution to more than a gentle tweak to a single frequency issue. If you have a null so strong you hear nothing in one location and almost nothing in another, EQ is a waste of amplifier power (no matter how much power you have on tap) and is more likely to cause other response issues than it is to solve the ones that already exist. The bell and slope of any EQ are going to be too broad to effectively deal with the problems you describe. I seem to remember you having a parametric EQ which is beneficial but often limited in just how many corrections you can make to an area such as "deep bass". A graphic EQ is all but worthless in solving room issues.

What have you done regarding research into solving your room problems other than using an EQ and installing more subwoofers? To begin with, all the tympanic surfaces you mention need attention and then you need some serious absorption devices which bring with them other issues of dynamic attentuation. I think you have the wrong screw all together and you need a sander instead of a hammer.




.
 

Gold Member
Username: Magfan

USA

Post Number: 1970
Registered: Oct-07
Andre, you mention having 3 bass sources at 50hz+. To determine the contribution of each you may shut them off 2 at a time and see what just the one driver does. Look for peaks / nulls in your fashion and keep track of what vibrates.

I don't know if such an equalizer exists, but a 1/3rd octave from say...10hz to 80hz may be able to help. But only at a specific listening postion. it'll be worse everywhere else.

What are your basic room dimensions? LxWxH Where is you LP in relation to the walls?

Didn't I tell you a couple years ago you were going to shake your house down?
 

Gold Member
Username: Superjazzyjames

Post Number: 1114
Registered: Oct-10
Don't worry about taking over the thread Andre. I was done with it for my own purpose and am glad someone else is getting use out of it.

Is carpeting the floor an option?

The graphic EQ could possibly help if tuned properly, provided there is such a thing as proper tuning in your room. Some rooms can adjusted to, others can't. Tuning may take hours especially if you've never done so. I'm guessing your room is not a good candidate for an EQ. It's important to make sure you use it for reducing strong parts of the signal, NOT boosting weak parts, especially bass. Boosting can cause your amp to clip even at low volumes which will blow your speakers. The deeper the part of the signal, the worse boosting will be. You might be better off with a smaller subwoofer.
 

Gold Member
Username: Magfan

USA

Post Number: 1971
Registered: Oct-07
First paragraph of Jan's #15685 is the 'clue'.
Can't fix bad dimensioned room with EQ. I would just add that perhaps you CAN fix such room, but only at a single listening position. The larger the sweet spot you desire, the less exact your EQ result will be.

Room treatments? Mandatory.

Again, what are the basic dimensions of the room? If any 2 dimensions are a multiple of another dimension or the room is square, that's a problem.
A smaller sub is not an option for Andre. Besides, if the sub and LP were located in the same locations, you'll end up with the same problem.
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 3034
Registered: Dec-06
Andre, you've never once mentioned any sort of room treatment devices. Until you do something with the room, it doesn't matter how many drivers you put in the space trying to minimize room nodes, the room will fight you and it will win. You have to go about this logically and IMO all you've done so far is go about getting the largest amplifier and the biggest driver and enclosure you could find. When the screw doesn't fit the hole, getting a bigger hammer isn't the solution. You can solve some of your problems with placement but the room still has the same dimensions no matter where you and the subwoofer sit."

Right. I agree that I forgot to mention room treatment. Add that as another option. I didn't go out to build a large sub to try and fight room modes. I wasn't even aware of that until I started trying to integrate it into my system. My rationale for it was headroom and dynamics. The point was that I wouldn't have to compromise integration and quality because of a lack of displacement. It was for those huge spikes of low frequency energy during movies that give the huge wow/realism factor, make you grip your seat, and give you the feelings that the audio engineer intended you to have. It was so that I'd never be stressing the system.

"Items in the room resonate at harmonic frequencies of the fundamental or of other harmonics. A tea cup full of liquid is not likely to have a resonant frequency between 14-20Hz. It is likely to have a resonant frequency at some upper harmonic of those frequencies. Which means just because your spec sheet told you the driver/enclosure could produce 14Hz, the tea cup's resonance doesn't prove that it is capable of doing so inside your room."

Although this is a possibility, I do not see any notable vibration at higher frequencies. This is a cup of red effervescent liquid 60 feet away on the opposite end of the house. The only spec sheet I used was the set of T/S parameters for the driver. It was the simulation software that gave me all of the projected information about the subwoofer. I made a few modifications after I first tested the subwoofer in the original configurations, and the measurements line up pretty well with the measurement software, but the Q of the driver seems to be slightly lower than that of the generic specs.

EQ is seldom the solution to more than a gentle tweak to a single frequency issue. If you have a null so strong you hear nothing in one location and almost nothing in another, EQ is a waste of amplifier power (no matter how much power you have on tap) and is more likely to cause other response issues than it is to solve the ones that already exist. The bell and slope of any EQ are going to be too broad to effectively deal with the problems you describe. I seem to remember you having a parametric EQ which is beneficial but often limited in just how many corrections you can make to an area such as "deep bass". A graphic EQ is all but worthless in solving room issues.

I have experienced these phenomena with my experimentation using the EQ and agree with you. For what it's worth, my parametric EQ has up to 24 filters and a Q that covers up to 2 octaves or down to 1/60th. Another thing I may have forgotten to tell is that my use of the parametric EQ is not only for dealing with room issues, but also for the ability to have several preset curves for different uses. I might have a different response set for low-level listening than high-level and for music and movies or different sources or locations in my room. I believe I can set up to 10 presets.

What have you done regarding research into solving your room problems other than using an EQ and installing more subwoofers? To begin with, all the tympanic surfaces you mention need attention and then you need some serious absorption devices which bring with them other issues of dynamic attentuation. I think you have the wrong screw all together and you need a sander instead of a hammer.

I've researched all of the stuff before - the problem is that I keep forgetting or letting things slip my mind OR never quite get a full idea of what I'm learning in the first place. I also have difficulty implementing solutions for one reason or another, whether it be money or resources. For example, I have all of these large filing cabinets in here, and while I've damped them the best I can for the time being, I can't just move them out of here altogether because there's no room anywhere else. I'll continue trying to find ways to solve these problems.

Andre, you mention having 3 bass sources at 50hz+. To determine the contribution of each you may shut them off 2 at a time and see what just the one driver does. Look for peaks / nulls in your fashion and keep track of what vibrates.

I don't know if such an equalizer exists, but a 1/3rd octave from say...10hz to 80hz may be able to help. But only at a specific listening postion. it'll be worse everywhere else.

What are your basic room dimensions? LxWxH Where is you LP in relation to the walls?

Didn't I tell you a couple years ago you were going to shake your house down?"


I've moved things around since my last post, but I did try each source alone and got similar overall responses from the speakers, but the subwoofer was a bit different. After moving it to the current location (I'll get to that), I found it had a similar response to the speakers within the same passband. The only sub 100hz null as of my last measurement was 46hz, but it's not there at the current LP. Reading my post, you'll see I have a parametric EQ with a lot of functionality already. It has precision down to 1/60th octave for frequency and bandwidth controls starting at 20hz (and I don't need more than that), as well as gain control in 1dB increments.

My room has a lot of weird dimensions and is very open to the rest of the house, but the actual room is 21x13 and the ceiling is vaulted (flat on top, though) from 8 to 10 feet. The very large opening makes one part of the room have a dimension of 35ft. I don't know how you'd enter that into a calculator. I tried and wasn't sure how to interpret it. My LP was on the side with the large opening (5 feet from long wall and 7 feet from short wall). I am now sitting 4 feet from the long wall and on the other side 5 feet from the short wall. And yes you did, but I haven't shaken my house down yet!

Don't worry about taking over the thread Andre. I was done with it for my own purpose and am glad someone else is getting use out of it.

Is carpeting the floor an option?

The graphic EQ could possibly help if tuned properly, provided there is such a thing as proper tuning in your room. Some rooms can adjusted to, others can't. Tuning may take hours especially if you've never done so. I'm guessing your room is not a good candidate for an EQ. It's important to make sure you use it for reducing strong parts of the signal, NOT boosting weak parts, especially bass. Boosting can cause your amp to clip even at low volumes which will blow your speakers. The deeper the part of the signal, the worse boosting will be. You might be better off with a smaller subwoofer.


My floor is carpeted - it's only a small corner that has tile. I think it's more of an issue with the whole floor vibrating than just the tile rattling. Tuning doesn't take me as long since I have a program (REW) to help me measure and tweak. My subwoofer has peak excursion at 23.5hz and then exceeds that below 16hz. It is capable overexcursion at full amplifier power (1800-2000w RMS) between 20-30hz and theoretically should take 2000w between 16.5-20hz. All of that said outlines places to specifically avoid excessive boosting (I consider 3dB to be OK or more if you have lots of headroom - I'll get to that in a bit). By smaller subwoofer, I think you may mean one with less extension?

First paragraph of Jan's #15685 is the 'clue'.
Can't fix bad dimensioned room with EQ. I would just add that perhaps you CAN fix such room, but only at a single listening position. The larger the sweet spot you desire, the less exact your EQ result will be.

Room treatments? Mandatory.

Again, what are the basic dimensions of the room? If any 2 dimensions are a multiple of another dimension or the room is square, that's a problem.
A smaller sub is not an option for Andre. Besides, if the sub and LP were located in the same locations, you'll end up with the same problem.


Right. I agree with your advice, but I outlined my actual use of EQ earlier in this post. I am often up and moving around while music is playing, which is why I may need a 2nd subwoofer ($300 to get the rest of the materials) - even with room treatment - to allow a large sweet spot. My speaker configuration does not allow a large sweet spot, either. I don't have a center channel to anchor the sound OR correct surround speaker placement.

--------------------------------------------

Now that I've clarified (as I obviously have issues clearly stating what I mean to say), I'll get to what I've done tonight. I first moved the subwoofer into the corner again (new amp, new tuning, new EQ, different settings and methodology) and ran a sweep at my LP to find the response. I the same problems (albeit at a higher level) and a bad null at 46hz. I tested each driver and got the same null at 46hz. This is also where the floor resonates with the tile floor the subwoofer is now on - however I believe I can decouple it enough to subdue the problem. With all 5 bass sources running at the same time (4 speakers + sub), the null was minimized. I had the idea of setting a 46hz tone playing and walking around with an SPL meter. I found that there was a cross-shaped area covering the room where this null existed (my listening position happened to be at the intersection of this cross, making it even worse), but the walls, corners, and some select spots around the room had strong response. I tested one of the new spots manually and it seemed to have strong even response in the range where the old spot suffered from a 10dB drop in output, which was promising.

This just happened to be the spot I used to have my listening position in when I had a 10" subwoofer and decent results... HMMM!!!!

I ran a rough test (EQ disabled of course, being a new spot) without phase correction or anything and had promising results. The new set of problems appears to be in the range below 27hz and the null at 185hz moved to 167hz in the new spots. I haven't measured the new response yet with phase correction and re-aligned speaker calibration.

A short story about the current listening position: My 10" Paradigm subwoofer sounded pretty good to me (at low levels, of course) and test tones made it apparent that the response suddenly dropped off below 27hz, and I could slightly hear something at 22hz. This is really weird because my measurements are showing that the response now with this subwoofer is similar, but not as bad as it probably was with the Paradigm.

Anyway I am seeing promise with this spot (but sadly not the rest of the room except near walls and corners and then in the next room over).


All that said... off to have fun.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 15689
Registered: May-04
.

" I'll continue trying to find ways to solve these problems."


"Until you do something with the room, it doesn't matter how many drivers you put in the space trying to minimize room nodes, the room will fight you and it will win."




"My rationale for it was headroom and dynamics."


"When the screw doesn't fit the hole, getting a bigger hammer isn't the solution."




"This is really weird because my measurements are showing that the response now with this subwoofer is similar ... "


" ... the room will fight you and it will win."


Read that again, Andre, " ... the room will fight you and it will win."



" ... but not as bad as it probably was with the Paradigm."



Don't fool yourself, Andre, the room is the same no matter how much power, EQ or drivers you put in there. The room is always going to give the same results in the bass region and until you address the room, all your measurements and position changes are just rearranging chairs on the Titanic.



" ... which is why I may need a 2nd subwoofer ($300 to get the rest of the materials) - even with room treatment - to allow a large sweet spot."


"First paragraph of Jan's #15685 is the 'clue'."



"Clues" are for mysteries, this ain't no mystery.



Andre, get you head out of the numbers and out of thinking more subwoofers are going to do anything. I understand that you're fairly young and you're excited about all this stuff and all the toys that go with it, but you ask for advice and then you go do whatever you had made up your mind to do anyway. Then you report these problems. You're fairly young and there are a few of us who are fairly old goats. Listen to what we have to say and learn from our mistakes instead of repeating them yourself. You cannot get what you want to achieve by adding more bass sources to the room. You need to step back from "more subwoofers" before you waste any more time and money. Just because you don't understand room treatments is not a reason to resort to more of what you think you understand but can't manage to get to work right. The room is the limiting factor here and you need to address the issues of the room and its contents or else you are just wasting time taking all your measurements and referring to all your charts. You have ten presets for this, that and the other but, do any of them actually sound good? C'mon, Andre, get real here.



"I've researched all of the stuff before - the problem is that I keep forgetting or letting things slip my mind OR never quite get a full idea of what I'm learning in the first place. I also have difficulty implementing solutions for one reason or another, whether it be money or resources."



Andre?! You don't understand the concept of room treatments but you "get" the idea of adding more bass drivers? C'mon, Andre! Room treatments are pretty basic stuff, you get rid of the excessive bass accumulations in the room's problem areas - which are consistent in each and every room - and you end up with more bass throughout the room rather than less bass in certain areas of the room and waaaaaaaaay too much in other spots. Modeling the room on your computer ain't gonna do this. All room treatments start the same way, treat the spots where bass accumulates. Simple. If you don't have the resources for room treatments, why would you have the resources for another refrigerator sized subwoofer? When you have the "resources", buying anything other than some absorption devices will be a waste of money.


Period!


I hate to send you there because the main guy who owns the company is far from my favorite person but, have you tried the RealTraps site? There are plans for DIY traps that are very inexpensive to create. Address the tympanic surfaces within the room first then address the room itself. This ain't rocket science, Andre. The guy who owns RealTraps proves that.



"Although this is a possibility, I do not see any notable vibration at higher frequencies. This is a cup of red effervescent liquid 60 feet away on the opposite end of the house."


What's the cup sitting on? Maybe that's what's vibrating and the cup is vibrating in response to the surface it's sitting on? It doesn't matter, Andre, making up excuses, moving the sub or "this isn't what I would expect" isn't going to change to room. Change the room and you change the results.



Period! If you're not interested in that advice, there's nothing more I have to add.


.
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 3035
Registered: Dec-06
Alright Jan I very obviously get what you're trying to convey. If it helps, I HAVE implemented room treatment (just absorption) for higher frequencies, but not low frequencies. You'll have to give me some time to do it, but I will look into room treatment for low frequencies as well. I recall stopping by RealTraps a looonnng time ago.

If there's a mode I want to get rid of, it's the series of multiples starting at 46hz that keeps creeping into measurements (I've seen 46, 92, 136 (almost), 186 (close)...

My current positioning has no nulls except for 92-96hz depending on how I set the phase and then there's ragged response at higher frequencies. There's a 5-10dB drop between 19-26hz. 200-300hz shows a 10dB dip (throughout the room, and I think it's the speakers (might try a nearfield measurement) and then the high frequencies are... bad. I'm more suspicious of the speakers than the room because they are old and cheap. Magnets lose charge, materials change in properties, and factory specs change, as well as low quality control and high variation at low prices.

I want to show you the response of my headphones and amp I use with them because I really like their sound and I might use it as a model for my own response (at least in the bass region).

Upload
Upload

The top is the response of my headphones and the bottom is the response of my amp with the bass-boost engaged.

I mention this because it has no issues with lack of bass, but at the same time never sounds "wrong" on a song. I have some songs that can be a problem if things aren't right on my setup and the headphones don't have any issues with notes that are too loud or soft.

Hollow Life by KoRn has instrumentation that hits 32hz, 38hz, and 48hz, 77hz, 86hz, and 97hz in the sub 100hz range. The way it's mixed makes any system setup problems very obvious.

Several songs I own have a 27hz fundamental that is hard to make sound just right without messing up other songs, but my headphones do it just right.

As horribly compressed and volume smashed as it is, Metallica's Death Magnetic album has a kick drum that is hard to make audible without making other songs overpowering. My headphones also have this problem, so it's sadly a mixing issue. It's the same with Disturbed's Asylum.

College is something that will likely drag me out of my house within 9 months, so big subwoofers and surround systems will no longer be in the picture, depending on the dorm standards. I know of some dorms where people know each other and blast music all the time, but there are others which have tight restrictions. That said, a small sub will probably still be in the picture considering that I tend to listen to music any time it's possible to do so. I'll wait to act until then, but I'll put focus here for now.

Even if/when I do Low Freq room treatments, I still don't have 115dB reference output capability from my sub and I'm pretty sure there are issues with the sub itself.

Maybe I'm just not thinking right...
 

Gold Member
Username: Superjazzyjames

Post Number: 1138
Registered: Oct-10
"Alright Jan, I very obviously get what you're trying to convey."

No such thing is obvious to Jan. Jan will not be satisfied that you've got anything until he has opened your head and injected it into your brain 777 times! So be prepared for more, it's coming!

You should treat the room for bass and post the results before continuing though. This will give you and everyone else a better idea of what else you need to do.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 15700
Registered: May-04
.

Andre, I'm guessing what you're showing here for the headphones has been lifted from the retailer's site and probably comes from the manufacturer. Using that response curve as a model for your subwoofer will probably not give the results you are hoping for. Headphones deal with quite different perceptual issues than do speakers, the most obvious and most important here is the fact phones are measured and heard in the extreme nearfield. In such a situation a declination of -10dB at 40Hz (referenced from 100Hz) and -22dB from the midrange region would not be an issue. However, in a room, taking into account room gain and the fact very little can actually be done to smooth in room bass response beneath about 70Hz, that response curve is going to sound quite wrong and will never be achievable in reality.


" ... the bottom is the response of my amp with the bass-boost engaged."


With the "bass boost on"?! Why? Why complicate things more than you already have? Then you add EQ in on top of that bass boost? You've got to be kidding me.



Where are you getting the frequency response specs for the albums you mention?



Andre, what I see you doing is making a lot of excuses for why things aren't the way you want them to be. " ... the Q of the driver seems to be slightly lower than that of the generic specs", "I'm more suspicious of the speakers than the room because they are old and cheap. Magnets lose charge, materials change in properties, and factory specs change, as well as low quality control and high variation at low prices."

Magnets do not loose their charge in the amount of time you're dealing with, materials are pretty stable over time - particularly poly materials, paper is stable for the most part other than humidity changes, caps and other filter elements aren't going to be suspect for twenty years and even then the tolerances are quite broad to begin with and not to be concerned with if you have a baseline to start from, factory specs can be held to within +/- 5% using modern manufacturing techniques, the "Q' of the driver you purchased is more likely to be held to a +/- 2% tolerance. The saying, "It's a poor craftsman who blames his tools", is apt here, Andre. Stop looking to other things to make excuses for the problems you are encountering. None of the "issues" you brought up should have any real world affect on what you are dealing with.

"Maybe I'm just not thinking right... "

I would tend to agree. You have some pie in the sky concept you wanted to accomplish but you lacked the skills and the knowledge to pull it off.


Join the club.


I know several of us had made comments regarding learning from your mistakes and not to expect perfection just because you have a lot of toys to play with. It appears to me you've just run smack into that wall at 120 mph. It also appears to me you've exhausted your resources when it comes to dealing with your problems. Here I'm not sure what to suggest other than what I believe has already been suggested and that is to head to a forum where there are more speaker designers to provide assistance. There simple are not enough people here with hands on experience in what you have to do you much good.


I will tell you I think one of your biggest problems is your reliance on numbers that come out of either a machine or a book. To my knowledge you've never taken a measurement of the subwoofer's actual response outside of a room. Nor do you have any idea what the response of your room is other than what your modeling software suggests. Now you put two unknowns together and you are struggling to make something work when you have no reference point from which to observe changes. So you move this and you measure that and you model something into the computer that really means nothing. My guess is your computer software doesn't include items in the room such as filing cabinets, windows and doors or the fact the room flexes in real life. My guess is your modeling software assumes you have a perfectly blank cube with infinitely solid surfaces.

Other than the presence of Ethan over at RealTraps I think one of the dangers of that site to you is you will get yourself sucked into all the numbers and calculations and you'll ignore the basics of making your room work with you. Once you do that you'll just have more numbers in your head but no real solutions and you'll head further and further down the rabbit hole.


IMO, Andre, you need to step back from where you sit and start over at the beginning. My recollection is you made your enclosure to the specs provided by the manufacturer. But you never checked the system outside of a room and away from any reflective surfaces to ensure the response was where it should fall. You don't have much of a grasp on the response of the room other than what you measure with a subwoofer you aren't certain of and what you model into your software which is incomplete. But you aren't getting good results from the software due to the room shape and the existence of real world living arrangements. So, how long do you think you can continue to move the sub and your chair around before you finally give up out of frustration?

As I've said, you have to deal with the tympanic surfaces within the room - including the room itself - before you can actually move forward rather than just sideways. Domestic rooms are not designed or constructed to support the type of bass response you want to achieve. If surfaces bend, absorb, reflect or resonate, you'll have problems. Taking measurements in such a room is a fool's errand. You have no baseline to go from for either the room or the woofer. Take out those file cabinets and do your measurements and you'll see a totally different room. Support the floor to add rigidity and you'll have a different set of measurements. Deal with windows and doors which are the most deletrious additions to any living space when it comes to deep bass response and look at the results of your measurements afterwards. But with those things undone, you're just a hamster running forever in a circle inside a spinning wheel.


Let's keep you away from Ethan over at RealTraps for now. Here's something from Jon Risch which is affordable, easy to accomplish, effective and safe when constructed as suggested; http://www.audioasylum.com/reviews/Accessory/DIY-by-Jon-Risch/Quick-and-Dirty-Ba ss-Traps/general/50/501157.html

http://search.yahoo.com/search?ei=utf-8&fr=slv8-hptb5&p=jon%20risch%2fbass%20tra ps&type=


You have to deal with the room, Andre, there's nothing else that's going to begin to actually solve your problems. Keep in mind the diameter of the trap will be relative to the lowest frequency it can affect. There are no realworld treatments which can affect frequencies beneath about 60-70Hz as the dimensions of the trap become overly obtrusive in a domestic setting. A good 60Hz trap will itself be approximately 48" in diameter. (Don't mess with rigid fiberglass at this point, don't overthink or over-attempt at this point. Bundled fiberglass is effective, cheap and easy to come by and deal with. Just work outside or in a garage, use gloves, wear long sleeves and eye/nose/mouth protection; don't ignore this warning or you will be sorry.) The good news is you can affect dramatic changes in bass quality and perceived performance by treating those midbass frequencies. Most music performed on acoustic instruments does not possess as much energy at the fundamentals as it will at the first harmonic. Treating the 80Hz response of the room will bring the 40Hz response into sharper focus. If you're getting your frequency information for the various albums as performed by electronic instruments, then you may never achieve smooth response as most electronic instruments do have high energy at the fundamental. Put things into prespective. This is were your numbers and charts need to get tossed out the window. You have to realize what you see predicted in all of these ideals is seldom if ever going to be a realistic situation in a real world room in a domestic setting. Until you place these woofers in a theater sized room without the obstructions of a domestic living room, you are not going to manage the results predicted on paper. No flexing surfaces in a theater, right? Concrete everywhere. No filing cabinets. The space has been treated acoustically for the best frequency response. You don't have that situation, Andre, and therefore you cannot expect those results in your room.

Do what you can with what you have and ignore all the numbers that tell you something else is possible when it isn't. Start with a few DIY traps in the corners behind the system. Then use your ears to determine the best location for the subwoofer. You know how to do that, right? Add more traps as resources allow. When it comes to bass frequency response, you cannot have enough absorption in a domestic setting. Each additional trap will in effect take the room more and more out of the equation making the room appear larger to the subwoofer - very much like stuffing an accoustic suspension enclosure. The danger in stuffing a room comes from the absorption of both upper frequencies and the dimunition of dynamics. Absorption is broadband and you cannot aim it at a specific frequency, you have to use a scattergun approach and in the end you will tend towars an overall smoother response curve. By removing the spikes in the mid and upper bass range you will perceive better overall performance even at those frequencies which the traps cannot affect. Absorption's largest detriment to many people is the issue of dynamics.

"I still don't have 115dB reference output capability from my sub ... "

And you probably never will in that room. The room is still fighting you and compression is the result of the buildup of pressure due to excessive bass being input into the space. Absorption here will actually assist you by lowering the overall pressure in the room. You will perceive and very likely measure an increase in dynamic power with traps in the room. You'll get excited about the results you achieve with bass traps and then you'll tip over into the region where you have overdone the treatments when it comes to having a good mix of live and absorptive surfaces. This is what most people do with traps and another reason I would prefer you stay away from the RealTraps site for now. I have a very good idea how they treat rooms and IMO they overdo the treatments to achieve what they feel measures right in terms of frequency. In effect they kill the liveliness of the space and leave you with a flatter response as the tradeoff.


Start with the things I've mentioned, Andre, then report back after you've done some experiments. I promise you things will get better with room treatments - if you don't go overboard as a result.

http://www.stereophile.com/content/era-acoustics-design-4-loudspeaker-sub10-subw oofer-measurements


http://www.stereophile.com/content/science-subwoofing








What do you intend to study in college?




.
 

Gold Member
Username: Magfan

USA

Post Number: 1978
Registered: Oct-07
Andre, any way to drag the sub outside....in as large an open space as possible? A big field would do, I know you must be fighting weather and power considerations.
You'll be able to take some 'quasi-anachoic' measurements in such a location. The fewer boundaries the better.....You'll have trouble getting rid of the ground plane, though.

Jan, in the paragraph after 'Join the club', you used the wrong form of 'there'.....confusing. And I believe you meant 'simply', not simple.

However, that being said, Jan is essentially correct. The room is ringing like a bell and making its own contribution given the huge energy input at fairly low frequencies.

Is it possible to 'over bass' a room?
 

Gold Member
Username: Superjazzyjames

Post Number: 1145
Registered: Oct-10
But it's okay for Jan to make typos Leo. The rest of us dare not slip though.
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 3036
Registered: Dec-06
I see there is some misinformation around. I'll try to clear it up.

About the equalizer - I never set any presets because I never could get the first one to sound right. Now it's actually pretty good, though, although something is missing.


http://www.headphone.com/learning-center/how-we-measure.php

That frequency response graph is from their own testing procedures, but yes, they are a retailer. There was also a misunderstanding of my meaning of the graphs. The first graph is the response of the headphones and the second graph is the amp I use to drive the headphones, not the subwoofer. Their combined response is what I am referring to. Now that you mention it, though, I forgot all about the difference between headphones and speakers in rooms while I was writing that. I should've known about that from when I read about house curves and how they compensate for room issues. Now there is no reason for me to consider modeling my response after the headphone+amp response.


As for where I get the frequency responses of the albums - I use a program called Audacity and run spectral analysis on specific parts of a song that I have issues with and so that I can correlate what I see with what I hear. I can easily see exactly what frequencies I am dealing with.

Your information regarding change of specs over time is useful. I am corrected. I guess I should be careful about what I read. If it makes any difference, my mains are from 1994 and my surrounds are from 1973 give or take a year.

I will tell you that I am still pretty sure something is off with the subwoofer that IS my fault, but I don't quite know what. I have measured it outside for a ground plane measurement, actually. I couldn't manage more than 20 feet from nearby surfaces and had to drive the sub pretty hard to minimize extraneous noise (luckily there was no wind or real noise that day). The measurement is from a year ago, and I've changed laptops since then, but I have the file somewhere.

The modeling software does not model the response of the sub in the room. I have two programs for the subwoofer. The first models the subwoofer driver in a certain cabinet (in this case ported) and port configuration. It also takes into accoun Q of leaks, box absorption, and port absorption, as well as environmental parameters. It models SPL, phase, impedance, impedance phase, port velocity, resonance, excursion, and many other things. It is just to design an enclosure for a specific response based on T/S parameters.

The second program measures the actual response of the subwoofer using a meter, all of which I have calibrated, and automates EQ settings (for a specific equalizer) for a desired response curve. It shows phase, modal, frequency, impulse response, and group delay.
There is no 'recommended' enclosure from the manufacturer for my specific application. However, many others have done the same as me with spectacular results, leading me to believe I have a build issue.

I think we can agree that my room is very horrid for bass response. There are 5 filing cabinets. One of them weighs over 1000lbs and the other 4 weigh several hundred. I have a window that covers most of one wall and a large window door as well.

The difference between electronic and acoustic instruments is something I have noticed. KoRn's songs, for example, tend to have an electronic component and they do have strong fundamentals. Their bassist tends to have a strong first harmonic.

Upload

The response hasn't been calibrated since I did this so long ago and I don't have a measurement file to correct it. The other problem is I don't know what the correction values are. You can probably visualize the slope of the graph being a bit less (it doesn't just fall like that). I can tell you that the correct response I got at 1 watt was 84dB at 44hz and fell to 76dB at 20hz, hence why I think something is off. I've re-tuned to 18hz instead of 12hz and done other things since then, meaning I'd guess more like 80dB at 20hz now.

Those are pretty horrid measurements considering it should be 90dB ground plane (everyone else who has done this got that) to 30hz and then 93dB at 18hz. You say I rely too much on numbers, but I don't know why no one else who has done the same thing isn't having output issues.
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 3037
Registered: Dec-06
Whoops college right... I'm not really sure, but I'm considering electrical engineering, nanotechnology, some other type of engineering, psychology, philosophy... hard to know or choose.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 15703
Registered: May-04
.

"Join the club.


I know several of us had made comments regarding learning from your mistakes and not to expect perfection just because you have a lot of toys to play with. It appears to me you've just run smack into that wall at 120 mph. It also appears to me you've exhausted your resources when it comes to dealing with your problems. Here I'm not sure what to suggest other than what I believe has already been suggested and that is to head to a forum where there are more speaker designers to provide assistance. There simple are not enough people here with hands on experience in what you have to do you much good."



Sorry, leo, all the "there" words are correct. "Simple" should have been "simply".



Still riding that grudge into the ditch, eh, leo?




.
 

Gold Member
Username: Superjazzyjames

Post Number: 1148
Registered: Oct-10
Leo, you're holding a grudge against Jan? I can't imagine such a thing! Try laughing at him and I do mean AT, not with him. It's much healthier.

 

Gold Member
Username: Hawkbilly

Nova Scotia Canada

Post Number: 1159
Registered: Jul-07
Andre, for what it's worth, I went through a similar exercise a while ago.....although our ultimate objectives are quite different, the basic problem was the same.....l was getting way less bass out of the room than I was putting into it. After a similar thread of discussion here (and help from Jan) I built some bass traps and put one in each front corner of the room. Night and day difference. Way more bass at much lower volumes. You have a rediculous amount of energy in the room already it sounds like. It needs to be tamed, not tuned. I've since tweeked things a bit more, and integrated a sub fairly easily. Your challenges are admittedly greater than mine, given you seem to want ultimate depth and amplitude, so you may have to do more to get there than I did.

Jan's right on the money (pun intended) I think.
 

Gold Member
Username: Hawkbilly

Nova Scotia Canada

Post Number: 1160
Registered: Jul-07
James, you're huntin' bear with a fly swatter.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 15704
Registered: May-04
.

I would think your software has the capacity to do some curves for room response. You'll need a few woofers and a few locations. Take your measurements and then average out what the room is doing to the frequency response before you add your main subwoofer. This should tell you where the main, repeatable room problems exist and you should be able to then take those into account in any further measurements of the room - like, as you begin adding bass traps. Just make your locations for speaker and mic repeatable down to the 1/4".



Looking at that graph (which I assume is of your sub/room) it would appear the peak at 44Hz is related to the peak at roughly 22Hz and the same at about 88Hz. The troughs follow the same pattern. Now, if that's a graph of KoRn's bassist, then it follows the pattern of how instruments deal with harmonics, though the harmonic of an acoustic instrument can oftentimes be as much as +12dB above the fundamental. So, what's that graph showing?



"The modeling software does not model the response of the sub in the room. I have two programs for the subwoofer. The first models the subwoofer driver in a certain cabinet (in this case ported) and port configuration. It also takes into accoun Q of leaks, box absorption, and port absorption, as well as environmental parameters. It models SPL, phase, impedance, impedance phase, port velocity, resonance, excursion, and many other things. It is just to design an enclosure for a specific response based on T/S parameters."



Yeah, that one's all but useless other than the pretty pictures it creates. You need it and nowdays you can't start building an enclosure without it but it is largely just a recipe for how to start thinking about the project. You can either follow the recipe by measuring out the 1/8" tsp. of cumin and the 1/4 cp. of arrowroot which will give you a passing resemblance to what the author intended - usually not that tasty - or you can think of the recipe as not much more than a guideline for how to bake a "subwoofer". Your problem right now seems to be you don't have the skills or the experience to draw upon to know when to fudge a recipe to obtain the results you want. That others have had better success than you could be attributed to several different factors. One could be the others didn't make this their first build and had an idea where to fudge numbers and how to make corrections for the real world. Another could be the others had a better idea of how to use the equipment they have for measurements. Or they just got luckier than you did, Andre. I don't know since I don't know their work. Actually, most of the items that software shows aren't that important to the final product as you needed to build it - certainly not as a first build project.



"The second program measures the actual response of the subwoofer using a meter, all of which I have calibrated, and automates EQ settings (for a specific equalizer) for a desired response curve. It shows phase, modal, frequency, impulse response, and group delay."


I'd go back again to recheck this program and make sure you have everything correctly set to minimize any user error problems. This program is still just another set of numbers though, Andre. What do those numbers mean? Without those baselines that I mentioned earlier, I can't imagine they mean very much when it comes to helping you work out the issues of the room and sub as a system. It looks like you have the recipe and you have the measuring cups, you just can't bake a cake.


"There is no 'recommended' enclosure from the manufacturer for my specific application. However, many others have done the same as me with spectacular results, leading me to believe I have a build issue."


If you have access to others who have built this sub, then possibly they can give you some help. My guess is you'll find they have, for the most part, not put their units into the sort of space you have. You may have a build problem but, how are you going to determine that you do and how to fix it? This is where the experience of not building the biggest subwoofer with the deepest response and the highest SPL as your first project comes into the picture. But you are where you are. I can't help you here, Andre, these are the sort of things you have to tear apart and stare at for a few days. That's usually pretty difficult with a subwoofer enclosure. I would tell you to trust the first program to have given you the basic recipe. Double check everything you can about the build and in cases such as this you generally have to decide to either make what you have work to the best of its ability or you tear everything down and start again. Without someone with more experience with this system, there aren't a lot of other choices.

IMO you're still shooting in the dark however. You can't expect this sub to perform well in an untreated room. That is just a fact of life when it comes to the type of project you built.


" ... the room will fight you and it will win."


Not to push my agenda but from my experience, stop worrying about getting measurements to do what you think they should. Deal with the room first. It doesn't matter how the sub measures if the room undoes everything you've worked on with the sub. Leave the sub itself alone for now and get the room as right as it possibly can be. Once the room is as good as it can get, then any sub you put in the room will have a better chance of success. Realize what the programs tell you probably isn't what you will actually achieve. Use other people's experience as your guide more than the recipe.


.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 15705
Registered: May-04
.

Andre, before you let go of the subwoofer for the moment; have you checked the impedance of the system? This is a vented system, right? Then you should be able to use the twin impedance humps of a vented system to tweak the system. If the peaks aren't measuring correctly, then you need to do some enclosure tweaking. This could be replacing a port or adding some stuffing inside the enclosure.



.
 

Gold Member
Username: Superjazzyjames

Post Number: 1150
Registered: Oct-10
That's interesting Chris. I'm hunting a fly, so all I need is a fly swatter.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 15706
Registered: May-04
.

"I'm not really sure, but I'm considering electrical engineering, nanotechnology, some other type of engineering, psychology, philosophy... hard to know or choose.


What sort of work do you want to do? There aren't many ads for a philosopher - not even in the New York Times. Most engineers have the thought process beaten out of them in college. Same for EE's.

Nanotech's looking to be exciting in the next several decades. But, if you aren't looking for exciting ...


What school, do you know?


.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 15709
Registered: May-04
.

One year ago; https://www.ecoustics.com/electronics/forum/home-audio/604510.html
 

Gold Member
Username: Superjazzyjames

Post Number: 1156
Registered: Oct-10
Jan, incase you don't go back into the phono thread, you're also a sore loser!

My response to your last thread in there: ROTFLMAO!

You wanted me to laugh? You got it!
 

Gold Member
Username: Magfan

USA

Post Number: 1980
Registered: Oct-07
Jan, I believe you meant the contraction of there are? The sentence makes more sense that way. It doesn't sound right if I read it as written, even with 'simply' in place of simple.
Now, the discussion of proper usage? See link. Several schools of though represented.
http://www.antimoon.com/forum/t576.htmI

I believe most philosophers are self employed.

As for higher education, I wouldn't worry about choosing a major right from the start. Many lower division classes are common. If you are interested in science, they will nearly all take lower division Chemistry and math courses, for example. You may want to bias your choices to the type of field you intend without having to be so specific. Even psychology, I'll bet, would benefit from lower division chemistry. Full on Psychiatrist, as you know, requires a full MD to start. For that you DO need to aggressively pursue the correct lower division courses, which are heavy in the sciences and might include selections from the psychology or sociology departments.
My nephew is in a psychology studies program and is spending the next semester in France. He even had to take proficiency test in the French language which he passed. Something that surprised me is that even though he is an undergraduate, he even has several 'patients' assigned by his department. Bright young man and he will doubtless succeed.
 

Gold Member
Username: Hawkbilly

Nova Scotia Canada

Post Number: 1162
Registered: Jul-07
Grow up James. You've gone here before and made yourself look like an idiot doing it. Don't turn this forum into your own personal attack platform with post after post of childish nonsense. I was beginning to think you could at least be civil. I guess I was wrong.
 

Gold Member
Username: Superjazzyjames

Post Number: 1158
Registered: Oct-10
Actually Leo, Jan did use the right form. "There simply are not enough people..." "They're" would not make make sense.
 

Gold Member
Username: Magfan

USA

Post Number: 1981
Registered: Oct-07
Sounds like it deserves an 'are'
There are simply not enough people......?
meaning:: there exist not enough people.
Somehow, as written, it doesn't sound correct.

there / their / they're quiz.....Jan, You'd better get no more than 1 wrong!
http://www.better-english.com/easier/theyre.htm
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 15711
Registered: May-04
.

"Jan, I believe you meant the contraction of there are? The sentence makes more sense that way. It doesn't sound right if I read it as written, even with 'simply' in place of simple."


Leo, to the best of my recollection, I've never seen nor heard anyone use a contraction of "there are". Other than misspelling "simply", I meant to post exactly what I posted, "There simply(sic) are not enough people ... ". Why would I have "meant" to use a contraction when I meant to use the two words separately? The two words exist as individual thoughts, no contraction required. You can argue with my placement of "simply" but, at best, that is up to debate in an informal setting such as this forum and I'm rather certain my usage is correct anyway. "Are not enough" is the phrase, to break that up by inserting "simply" between "are" and "not" would IMO be incorrect.

Sorry if it doesn't sound right to you, leo, but I wrote what I meant to write and the contraction "there're" is absolutely foreign to my understanding of the English language. I've pulled out my unabridged dictionary and, while it's getting on in years now, there is a reference to "there's" but no other references to any other contracted forms of the word "there".

http://www.grammarblog.co.uk/2009/10/therere/

http://www.uhv.edu/ac/newsletters/writing/grammartip2005.03.23.htm


The word doesn't seem to have much acceptance. Perhaps as a colloquialism, perhaps more regional than not but not as a word I would use. Besides, why criticize that I chose not to use a contraction? Would you have done the same had I typed "I have" rather than "I've" or "they are" instead of "they're"? Seem's like your stretching here, leo.



.
 

Gold Member
Username: Superjazzyjames

Post Number: 1161
Registered: Oct-10
I can be civil Chris as you have seen. I explained in the phono thread what happened there. I've had an issue with anyone in here except that one individual. If he leaves me alone now, no one will have to see anymore ugliness.
 

Gold Member
Username: Magfan

USA

Post Number: 1983
Registered: Oct-07
see the first link I posted:
Some are ok with (there're), others not. I'd never seen that that contraction until I looked for it.
And in regards to whether you would use it or not, as you will. I don't think I'd use that particular contraction, either. The sentence seemed....incomplete without 'are'.

Now, back to our regularly scheduled programming
 

Gold Member
Username: Superjazzyjames

Post Number: 1169
Registered: Oct-10
Leo, I don't think "there're" is a ligit contraction. I've never seen it and English (appart from spelling) was always a strong subject for me.

Andre, you mentioned one area of your floor tiled and the rest carpet. I'm guessing the tile is at the front door? So the sub should not be on or near it. You also mentioned rattling there. Are some of the tiles loose? If so, you'll need to corrected that in addition to room treatments. Otherwise, this will continue to be a problem.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 15712
Registered: May-04
.

"Are" is in the sentence, leo.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 15727
Registered: May-04
.

Regarding the deleted post from "nalintheturd":

It's not very comforting to realize the administrator of this forum has become so laize faire about the forum's rules that he will only delete offensive material when it personally offends him.



.
 

Gold Member
Username: Superjazzyjames

Post Number: 1205
Registered: Oct-10
That's how Brian has been as long as I've been here Jan. Evidently, that wasn't the case at one time.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 15729
Registered: May-04
.

No, you and Plymouth would have been gone long ago.
 

Gold Member
Username: Superjazzyjames

Post Number: 1208
Registered: Oct-10
Yeah, right!
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 3038
Registered: Dec-06
"Andre, for what it's worth, I went through a similar exercise a while ago.....although our ultimate objectives are quite different, the basic problem was the same.....l was getting way less bass out of the room than I was putting into it. After a similar thread of discussion here (and help from Jan) I built some bass traps and put one in each front corner of the room. Night and day difference. Way more bass at much lower volumes. You have a rediculous amount of energy in the room already it sounds like. It needs to be tamed, not tuned. I've since tweeked things a bit more, and integrated a sub fairly easily. Your challenges are admittedly greater than mine, given you seem to want ultimate depth and amplitude, so you may have to do more to get there than I did."
HI! In my testing tonight, I went around the room observing rattles or other phenomena which might disturb me at my listening position. The worst thing I found was probably the ringing of the file cabinets when a note stopped. They HAVE GOT TO GO, but I can't move them, so I may have to move the system instead. I DID manage to minimize it, though, so it was much less noticeable. I also found these rattles/noises that happened over a wide frequency range that I couldn't seem to locate, which I think may be drywall. My point is that I am finding all of the reactions of the room to be more of an issue than modal build-up and am thinking it may be better to address that first. I certainly want even response, too, so bass trapping is going to be a must as well. Thank you for the info.

"Take your measurements and then average out what the room is doing to the frequency response before you add your main subwoofer."
I think I have already done this considering that I've measured the subwoofer in at least 12 distinct locations at this point, and from several positions each. I can say that there is a cross-shaped modal region of the room where most of the problems exist with nulls for listening spots and then the spots that I have found cause the most modal issues overall (which would be good for trapping) are first the back right corner and then a close second the front left corner.
Looking at that graph (which I assume is of your sub/room) it would appear the peak at 44Hz is related to the peak at roughly 22Hz and the same at about 88Hz. ... So, what's that graph showing?"
Oops. I really should be more clear about what I'm showing when I post graphs. KoRn's bassist doesn't play low enough to have a 22hz fundamental, anyway. It's a graph I took a year ago of my subwoofer's outdoor response. I could not get an appreciable distance from boundaries and you can see it in the 50hz dip. It's actually a smooth 10dB drop from ~45 to 100hz and then the low frequencies weren't calibrated, so the drop in output is not as severe as it looks, to the tune of adding 10dB by the time you reach 15hz, meaning the drop isn't as severe, but it's still 8dB.

This first link is of a similar (but scaled down) version of what I have built:
http://www.hometheatershack.com/forums/subwoofer-tests-archived/5758-diy-tc-soun ds-tc-2000-15-ported-270l.html
This second link is to a thread of a build that was extremely similar to mine. Towards the bottom of the 6th page you will see relevant graphs of his in-room response. It gives me a hint that I may be having port loading issues. You can also find room pictures in the thread:
http://www.hometheatershack.com/forums/rew-forum/8294-2nd-time-around-measuremen ts-6.html

"If you have access to others who have built this sub, then possibly they can give you some help. My guess is you'll find they have, for the most part, not put their units into the sort of space you have. You may have a build problem but, how are you going to determine that you do and how to fix it?"
You can see that I am looking into similar builds. It turns out that other similar builds I see have similar or worse response issues to what I'm having IN ROOM. The scientific method has been my current approach -- change one variable at a time. Questions are good.

"Leave the sub itself alone for now and get the room as right as it possibly can be."
That would involve moving filing cabinets and drawing tables. It would be easier to move my whole system into another room than that. Maybe that's what has to be done...?
"Then you should be able to use the twin impedance humps of a vented system to tweak the system. If the peaks aren't measuring correctly, then you need to do some enclosure tweaking."
Initially, I almost measured the impedance, but then I got lazy and didn't. I suppose I'll have to do that to get more date... I should have measured the driver's T/S parameters when I first got it to confirm/adjust the design, but now it's a bit hard to do that...


"What sort of work do you want to do? There aren't many ads for a philosopher - not even in the New York Times. Most engineers have the thought process beaten out of them in college. Same for EE's.

Nanotech's looking to be exciting in the next several decades. But, if you aren't looking for exciting ...


What school, do you know? "
I can now remove philosophy and engineering from possible majors. Yay. I was looking at schools (hence my absence from here) and Albany or Rice University are two that stick out. There's still a lot of thought to go into it.

"One year ago; https://www.ecoustics.com/electronics/forum/home-audio/604510.html"
I didn't click the link, but I'm assuming that's my old build thread. I decided to just leave it be as it was getting blurry, if that makes sense.

....
Today I went into SPL mode by converting the sub into a quasi-TL by opening up the top end. I then found the resonant frequency of the system, 34.8hz, with nearfield measurements. I proceeded to create a pulsing 34.8hz sine wave with a low average level, but a high peak level (for max SPL test). The point of this was to see a) the maximum SPL I could achieve in my room and b) how much output I need to get the levels of impact I am looking for. It turns out I could manage output levels of 122db in the corner and 121dB at my listening position (2000w drive level). It turns out this is also the level I would need to get the visceral feeling. The problem was how my room reacted. The speaker actually vibrated a foot across the floor, every picture was jumping off the wall, all of the books nearly fell out of the bookcase (I had to pick 8 back up and shove ALL of the books back in which were about to fall out), the door was rattling all over the place, all of the filing cabinets acted like they were about to launch into space, several other things fell over, and one of the lights went out. It was ridiculous. I found that all of these things started happening at the top range exceeding 118dB. So THIS is one of the reasons why people have dedicated theaters!

All that said, I'd still expect the same output from a 12" or strong 10" in the same alignment. There has to be some sort of issue.

I may have to move into a new room...?
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 15730
Registered: May-04
.

"The worst thing I found was probably the ringing of the file cabinets when a note stopped."


"I also found these rattles/noises that happened over a wide frequency range that I couldn't seem to locate, which I think may be drywall. My point is that I am finding all of the reactions of the room to be more of an issue than modal build-up and am thinking it may be better to address that first."



"As I've said, you have to deal with the tympanic surfaces within the room - including the room itself - before you can actually move forward rather than just sideways."

OK, you now understand what "tympanic surfaces" refers to, correct? If it vibrates, it resonates. If it resonates, it is tympanic. If it is tympanic, it screws with your response. Your walls are subject to vibration just as any other large surface is subject to vibration and resonance however the issues tend to go deeper than the drywall and extend to the construction of the room surfaces. Cutting holes for windows and doors reduces rigidity, ventilation systems open to the room introduce their own resonances (which are nearly always unaccounted for in measurements but you're dealing with a Helmholtz resonator of sorts with the HVAC system's venting - it's a minor consideration in most cases but aggravating when it becomes an issue) and, unless the room was constructed with rigidity in the deep bass region as a priority, just the joins between each stud and joist serves as another weak point. There's not much you can do in the end to re-do previous construction. This is how houses are built and moving into another room will still present those same issues. Room programs however assume maximum rigidity of all surfaces and therefore tend to be misleading when you're trying to search for solutions to frequency response problems. All of your projections for deep bass response at high SPL are made on paper and seldom actually become reality in a typical room. In a purpose built theater, yeah, they can work, but in a typical domestic setting, no.


"I certainly want even response, too, so bass trapping is going to be a must as well. Thank you for the info."


Absorption works by reducing pressure in the enclosed space. It's presence will minimize the problems you're having with room and content vibrations but those problems really go deeper than traps can address. When you begin to use traps prepare yourself for the frustrations of not being able to affect deep bass with any trap due to the dimensions of the pressure wave vs the trap diameter. I don't want you goiing into this thinking traps are the final solution to all your problems, they are not.


"It's actually a smooth 10dB drop from ~45 to 100hz and then the low frequencies weren't calibrated ... "

"Initially, I almost measured the impedance, but then I got lazy and didn't. I suppose I'll have to do that to get more date... I should have measured the driver's T/S parameters when I first got it to confirm/adjust the design, but now it's a bit hard to do that... "


Minus ten dB down at 45Hz is ... uh, ... not what you were aiming for in a semi-anechoic response I would assume? Andre, I haven't done any speaker building in quite a few years now but I never saw any build instructions that didn't end with measuring the impedance hump(s) of any sort of enclosure type. That's how you assure proper alignment in a vented system and how you reach the correct system Q, Fs and F3 in a sealed system. If you haven't done that procedure, you're kinda pi$$in' in the wind with anything else you do to the system or enclosure. Not checking impedance and not adjusting for correct alignments is like trying to take a photograph without setting an aperture speed or F stop. Adjust the impedance for correct alignment before you do anything else. The T/S parameters of the driver are set and you can't change them. You should have measured them before you began building but you didn't. You can generally be assured they would not vary more than a few %'s and the issues you are facing are not going to change due to a couple of decimal points in the Qts of the driver. System alignment in the real world with the driver you have is far more important than what a small change in T/S parameters would do. Again, don't look to someone or something else as the problem. In this case you didn't do a complete build if you didn't adjust the alignment according to the actual impedance of the system. Suck it up, Andre, and do the job you were supposed to do when you began this project.


I can't get either of your links to other builds to work. Do you know how to place a proper link in this forum? If not, ask and we'll provide instructions. I'd like to see what others are accomplishing with this project.


"You can see that I am looking into similar builds. It turns out that other similar builds I see have similar or worse response issues to what I'm having IN ROOM. The scientific method has been my current approach -- change one variable at a time. Questions are good."


I thought previously you had said other builders were having better success with this project? Well, the point is the room has to be dealt with first and foremost. If they aren't dealing with the room either, then they will also continue to have response problems. You don't need to follow their lead in that direction. I have to disagree with your "approach" - it is not "scientific" to disregard a major step in the process of building the project. You are assuming a "scientific approach" means going by numbers you see on paper or in your computer. Far from it. I'm not criticizing, this is your first project and you learn from everything you do. If anything, I would suggest this is a lesson in not building the biggest and loudest project first. Check the impedance and make adjustments then proceed from there.



"Today I went into SPL mode by converting the sub into a quasi-TL by opening up the top end"


A "quasi-TL" is like being "sort of pregnant". TL's are such because of their pipe dimensions (volume and length) and I know of no other enclosure type that can become even a "quasi-TL" without a complete rebuild of the enclosure. Either the pipe of a TL is tuned to the quarter wave of the system resonance or it is not. I would be highly suspicious of your measurements but, if you are getting a Fs of 38Hz and if you have anything resembling a quarter wave pipe, then you're just seeing the length of the pipe and not much else useful to your project - which is not a TL. Stuffing in a TL is critical to performance and is not likely to be anywhere near the same as any other enclosure type as most of the stuffing is at the front of the pipe in a well designed TL. I'm not sure what you actually had when you opened to enclosure - a Helmholtz resonator? - but you might want to rethink your numbers here.


" I found that all of these things started happening at the top range exceeding 118dB. So THIS is one of the reasons why people have dedicated theaters!

All that said, I'd still expect the same output from a 12" or strong 10" in the same alignment. There has to be some sort of issue."



Yep! You've found one of the reasons people build dedicated theaters. You just aren't going to achieve that pie in the sky response until you get away from a domestic room shared with a subwoofer.

IMO, we've identified two major issues you need to deal with before the project can begin to move forward. First, check impedance and adjust for alignment. Second, deal with the room and the surfaces within the room. Finally, realize that numbers do not tell you everything that is going to happen or has happened in the real world. Experience and skill play a large part in how successful you are. It's not so much thinking outside the box as it is thinking within the constraints of the enclosure in this case. Knowing how to make lemonade from lemons is a tough thing to learn and it seldom comes to the impatient. Step back and look at what you have and figure out how to proceed to the next level. Another room will simply present another set of problems. It may not be bookcases but it will be something. Take your time and work through the issues we've discussed here. And remember, the world is full of garages and closets full of first experiments. No matter how this project turns out, Andre, the important thing is to learn from it and learn how to think through the sort of problems you're having now. There is no substitute for experience.





" I was looking at schools (hence my absence from here) and Albany or Rice University are two that stick out. There's still a lot of thought to go into it."


I don't now anything about Albany and I don't really know you, Andre, but I would guess you would be a very good match for Rice.



.
 

Gold Member
Username: Magfan

USA

Post Number: 1990
Registered: Oct-07
Andre, when you look at a school, do you find out what 'reputation' the school has in whatever field you are interested in?
For example:
http://engineering.stanford.edu/
a top notch engineering school. great rep, too.

So, you've removed engineering and philosophy from your list? Have you considered architecture? Anything in the public service sector interest you? Peace Corps? Diplomatic Corps? Teaching?

But, the bottom line is still the same. In EVERY field there are stars and drones. I've worked with maybe a couple hundred engineers. Many would just 'phone it in' and when they couldn't think of something would come up with some BS for me to do (process technician). Many others were good intentioned but simply had too much on the plate. The few? Really creative, with good problem solving skills, experimental orientation and the will too succeed. The last were almost unpromotable, since they were irreplaceable.
In the law? Most attorneys make good money, no doubt. But the real money makers are the top couple percent. Same with acting. A huge corps of journeymen you don't hear about but see in every movie. The extras and crew. The 2 or 3 stars of the movie? Probably make as much as everyone else put together.

What are Albany and Rice University known for? Is it possible to take some undergraduate courses at the local JC while trying to figure this out? You may 'waste' a few classes that won't transfer. But if you know 100% what you want to do and where to get the upper division courses, you won't waste a single class. Lower division English and some of the other required in 'general studies' should be good anywhere you want to go for upper level classes.
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 3039
Registered: Dec-06
I have a project to finish (but I have to start first, hahaha) for a class, so I can't comment RIGHT NOW, but I can at least provide those links. I was in somewhat of a hurry when I posted the last thing and didn't hyperlink.

When I said some others are having similar or worse problems than me, I meant in terms of their in-room response curve, not output. They always fix the response curve, of course, with a little work. Here's a guy who had this same design (he has since built a second one, co-located):

http://www.hometheatershack.com/forums/rew-forum/8294-2nd-time-around-measuremen ts-6.html

Then this one is the scaled down version of the same basic design that uses a 15" driver.

http://www.hometheatershack.com/forums/subwoofer-tests-archived/5758-diy-tc-soun ds-tc-2000-15-ported-270l.html
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 15744
Registered: May-04
.

I notice no one in these links has any explanation of how bass traps operate or even what they should accomplish. Despite the fact one installation looks to be in a purpose built room, I'm surprised the measured response is as smooth as it appears in their representations. Seems a waste to spend all that time and money, buy all the measuring gear and argue about how this should be or that shouldn't be on a mofo super-woofer when you don't know to spend money and time on the room to get the best from the woofer.


.
 

Gold Member
Username: Magfan

USA

Post Number: 1999
Registered: Oct-07
Does this help?
https://www.ecoustics.com/electronics/forum/accessories/42661.html

Worthwhile read
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 3040
Registered: Dec-06
Alright.
"OK, you now understand what 'tympanic surfaces' refers to, correct? If it vibrates, it resonates. If it resonates, it is tympanic. If it is tympanic, it screws with your response."

Yes. I am aware of the things like the tympani (orchestra) and tympanic membrane (eardrum); I just never responded directly to your mention of tympanic membranes. And wow yes it sure does mess with the response. I had someone hold the SPL meter in the listening position while a 22hz sine wave was playing. This frequency causes a strong response from the walls. By pushing against the wall opposite the subwoofer, the reading went up 2dB. The same happened when I pushed against the BACK door (which we never use) that the subwoofer is by.

"This is how houses are built and moving into another room will still present those same issues."

Although this is true, my mention of moving the subwoofer is in the interest of decreasing the volume of the space it has to fill for the room gain effect and pressurization. I realize this could worsen modal issues, so I'd have to see if it gives the correct balance of quantity and quality in the COMPROMISE I was trying to avoid.

"When you begin to use traps prepare yourself for the frustrations of not being able to affect deep bass with any trap due to the dimensions of the pressure wave vs the trap diameter."

... and my problems are occurring mostly in the deep bass <30hz in the current listening position. The addition of traps would help mostly with the upper frequency issues that occur as I walk around the room, but modal ringing (I think) would be improved.

"Minus ten dB down at 45Hz is ... uh, ... not what you were aiming for in a semi-anechoic response I would assume?"

Clarify: The peak is at 45hz and drops down 10dB by the time it gets up to 100hz.

"Adjust the impedance for correct alignment before you do anything else."

I will have to. For now I've left it alone since I'm busy again.

"I'm not sure what you actually had when you opened to enclosure - a Helmholtz resonator? - but you might want to rethink your numbers here."

Whatever it was, it was some sort of mixture between an enclosure and a giant port. All I know is that the driver's acoustic load (38hz) was related to the length of the open-ended tube.

At Leo: Interesting post. The college idea has evolved towards possibly a liberal arts college for undergraduate studies (maybe a major or two in some major science field or math or a minor in something like philosophy that will complement the major), then the grad studies would shift to a school known specifically for their reputation in the field I end up focusing on. My choices come from balancing several factors of what I am trying to achieve.

"I notice no one in these links has any explanation of how bass traps operate or even what they should accomplish. Despite the fact one installation looks to be in a purpose built room, I'm surprised the measured response is as smooth as it appears in their representations. Seems a waste to spend all that time and money, buy all the measuring gear and argue about how this should be or that shouldn't be on a mofo super-woofer when you don't know to spend money and time on the room to get the best from the woofer."

Although they aren't explaining it, I'm sure they know about bass traps. That wasn't the focus of the thread. I think what they were going for was SPL at the listening position for the most part. My biggest problem right now is with the extraneous noises I can hear from the room at frequencies that are not friendly to my seating position (they aren't as loud and so the spots where it is loud have rattles).

Leo, I've read the majority of the articles (some time back around when I joined), but it's still interesting to read again.

Right now I'm having less annoying problems than when I was in the old configuration, but the ultimate effect I'm trying to achieve will require a purpose-built room (no rattles), but I believe I can get much closer to it by getting away from the filing cabinets and tables that are causing a large amount of my problems in here. I may end up showing pics so you're not trying to go off of my muddy descriptions.

Adffadflkefnein.}
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 3041
Registered: Dec-06
Issues between 30-200 hertz have been effectually eradicated, finally managing a preset on the EQ and phase/delay settings that give great sound at the preferred listening level (in that freq range).

The problem now in the bass is the ultra-low range from 15-27 hz that was the whole point of building a large subwoofer. Its presence is lacking and this is reflected on the SPL meter. There is not much point in boosting between 19-25hz it as it does not fix the problem. It merely causes rattling around the room that takes away from the effect of the content being played as well as lowering headroom. This is one reason there is consideration for moving the system to a smaller space. There should be more room gain at those low frequencies,

Any music (even VERY bass-heavy) now requires ridiculously high master volume levels to exceed 100w drive levels. This is only because of the increased output sensitivity at the new positioning. The music has good energy/drive and mostly meets expectations, except for the upper range.

Movies now have dramatically increased impact, but those frequencies <25-30 hz aren't making themselves known at all and it could be so much more. During the loud moments, the level meter often hits the yellow, indicating less than 3dB of headroom before the clip lights will come on (clipping is 2000w into 4 ohms) AND elevated distortion levels (which ARE audible depending on the content). At times it DOES hit the red, and the sound is badly affected. This still seems to call for a second subwoofer or more efficient setup.

Aside from the area below 200hz, it is now readily apparent that the current speaker setup (both positioning and the speakers themselves) needs some improvement. These speakers are now a big limiting factor in the sound quality.

The amp's fan needs to be replaced, too, because it messes up those quiet moments that are supposed to add suspense and drama. The same goes for the lighting and small TV. The realism on the visual is none.
 

Gold Member
Username: Superjazzyjames

Post Number: 1310
Registered: Oct-10
One thing I'll tell you: Don't let the amp clip! Clipping will blow your speakers!
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 3043
Registered: Dec-06
I'm more concerned with slamming the driver against the former plate than overheating the coil, as that will probably happen first in my case. A full voltage signal from the amp will put me in danger below 35hz.

Not only is it bad for the driver, it also startles me pretty bad.

Curiously, I dragged the SPL meter out with some music playing (cranked) while the level meter was dancing with the clip light (no it never actually lit), showing 117dB, with the corrected value being 121dB. much better than the previous setup. and what I was shooting for when I originally 'designed' it. However, the frequencies below 27hz suffer a weak output at my LP.
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