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18" Build Thread

 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 2968
Registered: Dec-06
Okay.. in the past I never got around to it, so I am starting this build thread and am planning to get start next week by ordering the driver.

If you know me.. you know I've been through some pretty insane subwoofer designs. The problem is... I would never get the money together in a reasonable time for those projects.

So I've decided it's now or never.

The current plan is to build a passive enclosure, EBS-type alignment, 25cubic feet tuned to 14hz using a 10" port (length 34"). The dimensions should be nearly 2x3x5 feet (and volume displacement with bracing, port, driver, etc.. will bring it down to 25cu. ft).

The driver will be a FiQ18, with a displacement of .115 cubic feet (70%BL xmax), not amazing, but it'll be okay.

The driving force will temporarily be my old Yamaha HTR-5740 (maybe 200 watts if I'm lucky). That comes out to 113dB 1meter.

Then next I'll either build a duplicate to lower distortion (and increase headroom) OR I will buy the amp for ~1000 watts for one driver, or 900w/driver when there are 2 subs in parallel.

It's possible I might go with a bit lower tune, but then I'd switch to an 8" port to keep pipe resonance up high enough. Then the port velocity looks a bit high, so I may just stick with my current plan.

Enough of that then... I'll try to keep it updated somewhat.
 

Silver Member
Username: Magfan

USA

Post Number: 651
Registered: Oct-07
Andre, good to see you back!

I have a Carver Cube, the M-400t which has a noisy channel and apparently needs full re-cap and a good going over.
It is 200x2 @8ohms and bridges to 500x1 . Runs fairly cool and should be good for a sub. Speaker connectors are JUNK but can be replaced. (old clip on style) Drove my panels for 2 decades without complaint, except from the neighbors.

If your proposed driver is a DVC model and 4ohms or greater per VC, this'd work fine.

Let me know::
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 2969
Registered: Dec-06
The driver can only be ordered with up to a D2 coil, but I'm actually in the process of seeing if I can request a D4 coil.

The Cube may be cool, but I don't like the idea of running things amp-limited. Even at maximum output, the driver is only at half the xmax. The final amp will be able to drive one sub past mechanical limits below 10hz and past xmax below 34hz. With two subs, it's 12 hz and 13hz for xlim/xmax. What that really means, of course... when the ground starts to crack in the movie, it might also in the room.

As for music, I might make a way to seal the port... Even build an LT circuit possibly.

Maybe I misunderstood what you meant though?
 

Platinum Member
Username: Nuck

Post Number: 13992
Registered: Dec-04
Andre, Leo is offering his amp to power your project, instead of that THING that you mentioned.
 

Silver Member
Username: Magfan

USA

Post Number: 655
Registered: Oct-07
Thanks Nuck,
i owe you one!

Andre (slapping noise)
Want the Cube for Postage and handling?
Call a dude named 'Roland' as he is the acknowledged Carver Expert and will be able to tell you how much a recap would be. I'll look for a link.

I know you want to do structural damage to the neighborhood, but short of your planned KiloWatt amp, this cube is a real animal.

What is D2 / D4? A sub with a pair of 4 ohm coils will work, won't it?
 

Silver Member
Username: Magfan

USA

Post Number: 656
Registered: Oct-07
Support your local DIY'r
 

Gold Member
Username: Mike3

Wylie, Tx USA

Post Number: 2233
Registered: May-06
http://www.carveraudiorepair.com/
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 2970
Registered: Dec-06
Oh wow, I'm sorry. I messed that one up!

I'm planning on getting the sub in dual 4-ohm

Yeah I'll do that stuff, real nice of you

.
 

Platinum Member
Username: Nuck

Post Number: 14001
Registered: Dec-04
Good stuff, Leo!

I feel like we have raised Andre ourselves...in a pack of wolves kinda way.

Mowglie
 

Silver Member
Username: Magfan

USA

Post Number: 657
Registered: Oct-07
Thanks for link:
I hope that is Roland. He is considered a Carver Guru type.

Andre, get some estimate for a rebuild and if it is in line with your $$$ situation, let me know and we can than go offline and arrange for shipping.
I'll look at your info and try to figure out shipping costs. Cardboard / tape is real cheap, but USPS or whoever will be a few $$.

Let me know what you want. The amp isn't going anyplace soon, but you gotta fix it and USE it.

Just like Bob intended!
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 2971
Registered: Dec-06
I'll let you know what happens, may be a few days or more
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 2972
Registered: Dec-06
The sub design has been changed to using Sonotube with MDF endcaps for the enclosure. The same basic design still applies.

The size will be a ~30" diameter tube that is over 6 feet tall.

Still working out details.
 

Silver Member
Username: Magfan

USA

Post Number: 668
Registered: Oct-07
Here 'ya go, Andre.
'Ultimate Weapon' of subs.

http://www.passdiy.com/pdf/el-pipe-o.pdf
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 2974
Registered: Dec-06
Thanks, Leo, but I have been through all the designs before (mostly..).

I am still considering a TL as another project.. probably for another area.

So far, I've worked out what to use.. tentatively..

8'x4'x3/4" MDF

30"x6' Sonotube

10"x3' Sonotube

Bed mattress foam (?)

Liquid Nails (?)

Black paint/primer/sealer (?)

"Sock" of black fabric (?)

2 sets of Binding Posts (satin nickel)

Cat 5 Wiring (?)

All necessary tools.. (have a friend to help with that)

Dowels for legs

Caulk??

Driver mounting (T-nuts?)


At the moment. I can't think of anything else I need..


Currently, I've found someone with 8' 24" sonotube... 8Pi cubic feet.. a bit small..and limits placements options in this room with a semi-vaulted ceiling. I've found 8' 10" sonotube for $6 a good possiblity for the port.. maybe a dual port for dual tuning.. but how to block sufficiently?


As for my room's acoustic properties... imagine a trapezoid sitting on a rectangle, 13'x21'x(7.5', 11.5').

It's full of uneven surfaces, pictures all over the wall (hmm... they all.. fall..down...), a large macromay, a large drape, lots of large furniture (empty filing cabinets and other things)..

I think that's a good thing for the sound.. not an acoustics expert.... some bad things in the room for sound as well.

A LOT of sound leaks through the opening in the room...
 

Silver Member
Username: Magfan

USA

Post Number: 680
Registered: Oct-07
The 4x8 sheet of MDF will make a pretty large enclosure. You may need some, probably lots, of 1x2 for bracing and a quart of woodglue.

Padding at a local fabric store. They'll sell some poly batting you can fluff up to the right density.

Clamps will come in handy, too.
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 2976
Registered: Dec-06
Modeling the largest size enclosure I can make with a 4x8 shows that it's less than half the required size, severely limiting efficiency at low freqs. (more distortion). The sonotube will allow much better efficiency, and higher impedance over the main range it will be used for. When I add the amp in, the capability will be in the mid 120s down to 12hz (and 130, in room, around tuning frequency). This is for movies as well as music..

The padding I'm looking into
 

Silver Member
Username: Magfan

USA

Post Number: 683
Registered: Oct-07
Andre, Once you BUILD this, are you going to have room IN the room?

I suspect 110+db at anything below 50hz will cause structural damage.

But, I don't care HOW it's done, that Pipe TL from Pass was awesome? No?
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 2977
Registered: Dec-06
It's not a small room, and I've planned for a few placement options.

Ehh.. idk... I've been at 110dB at 45hz with my mains/surrounds only.. quite a kick, but no damage :p

Yes it was awesome..still is... good bedroom project.. maybe..
 

Silver Member
Username: Magfan

USA

Post Number: 688
Registered: Oct-07
One more nutty remark:

Once you Build this sub, what happens if you decide to MOVE it somewhere? You'll have to tear out a wall and hire a flatbed.
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 2978
Registered: Dec-06
Hah funny

If I did not have any plans of taking this sub somewhere soon enough, I would've bought 2 IB318s instead and installed as an IB in the wall.
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 2979
Registered: Dec-06
Okay I'll update you now...

I got the driver earlier this week and it's about what I expected- 18" driver which looks to have about 2" worth of throw (p-p). Of course I only have about 100w (measured) of amp power I can use right now. 100w at 7hz gets about 1" peak to peak, will take 400w for full 2 inches.

I picked up the Sonotube today and it is about what I envisioned. I had to buy a 12' piece (planned on it anyway since I am planning on a second sub in the future). This is all assuming less than optimal room effects.

I should have enough power to drive it to 115dB or so in the room down to 10hz. With the amp it should increase to 123dB (excursion limits) and then about 127dB with two subs.

Of course the point of all this headroom is low distortion at lower levels.

I am hoping to get to construction soon
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 2980
Registered: Dec-06
Ahem..

Getting MDF Thursday and planning on starting

My current speakers can't really make it below 40hz. I remember the guy I bought these from saying "these already have subwoofers in them so you don't have to buy one." I was like ???? hahahha. Its output below 50 isn't great either. Although... it can still be felt at upper volume, unlike the subwoofer I blew.

My last subwoofer didn't make it below 27hz, and at 27hz it had to be turned up max to be able to hear it, which is crap. It was a quiet subwoofer - certainly not up to the task of movies, and not up to music as I preferred.


One of my main goals with this new subwoofer is to be able to hear as low as possible with it. In the final install capability, I'm hoping to be able to hear into infrasonics pretty strongly.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 14284
Registered: May-04
.

Uh, Andre ... you can't hear infrasonics; http://www.answers.com/topic/infrasonic
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 2981
Registered: Dec-06
Ahh, the definition is correct, but it should be applied based on volume.

The equal-loudness contours show that 30hz is 'inaudible' if it's not loud enough, which is the sad case with my current system. If it is there, it's very quiet. I see I need 100dBC SPL to achieve 70phon. I can achieve that by pumping ~20watts into my speaker with a modified tuning (just as a test, temporary). Weakling speaker :-(

According to the equal loudness model to 15hz, I should be able to achieve 80 phon there. I should alse certainly be able to achieve clearly audible stuff to 12hz, just not LOUD audible, more felt for sure :-)

It does not have a pitch below about 16-17hz, as the individual cycles are too long in duration and do not "blend" like they would at upper frequencies. I've heard it's rather eerie.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 14286
Registered: May-04
.


"dBC"? OK, you've posted something I don't recognize. Explain, are you simply tying "C" weighting to your numbers? Weighting systems are bogus, Andre.



Surely your hearing does not simply switch off at a certain frequency as if you had a brick wall filter inserted in your brain. At your age you should have more extension to your hearing (and a physiology that is still developing) than most of us who have been around for awhile and you can experience a one or two Hz advantage over us.


HOWEVER ...


The first question would be, where are you going to find those 15Hz signals you wish to hear? Digital encoding does employ brick wall filters at 20Hz so there's no material available from a convenient music source for your desired frequency. Analog is intentionally rolled off beneath 25Hz to minimize problems associated with analog.


The second question, Andre, as always is, why?

Personally, I've never understood your fascination with on paper figures indicating you can achieve such and such SPL at this or that frequency. Not only are you forgetting the limitations of the equipment available to you (actual power available from a real world amplifier working into a real world load at ultra-low to infrasonic frequencies) and the inherent compression of any speaker system operating at high SPL and low to subsonic frequencies but you are omitting the most important component of your hearing process, your brain.

Phons are in many ways voodoo numbers. At approximately 17Hz your hearing is designed to go away and your physical reactions to take over as you are treading into brain wave territory and these are not things to be screwed with.

"I've heard it's rather eerie."

Well, yes, since you're telling your brain to function in a manner it is not designed to accomplish. If you are so interested in an errie feeling, I would suggest you investigate binaural beats rather than a humongous subwoofer with limited useage for real world applications. Isochronic tones can be played through your speakers and they are by many considered binaurals on steriods. There are Schumann Resonance generators available which use antennas based on Tesla's original calculations for Earth's resonant frequency of 7.83Hz. Any of these will provide a far more wide ranging "errie effect" than your experimental subwoofer that can only play tones generated by a rather expensive signal generator in isolation to any other source.

Why would you want to play 12-15Hz signals, Andre?

I understand you are climbing the mountain because it is there but you seem too fixated on calculations (many of which are debatable or not achievable under realistic situations and certainly not within the confines of a domestic bedroom) and you are forgetting the purpose of a decent audio system.

Really, Andre, what do you expect to say you've accomplished with this "experiment"? Hearing loss? I can tell you from experience that is nothing to brag about.

.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 14287
Registered: May-04
.

"Hoffman's Iron Law":


One of the most fundamental design principles that the new DIY speaker builder must learn is generally known as "Hoffman's Iron Law". First formulated back in the early 1960's by Anthony Hoffman (the H in KLH), Hoffman's Iron Law is a mathematical formula that was later refined by Thiele and Small, whose work now forms the basis of all modern loudspeaker design.
Hoffman's Iron Law states that the efficiency of a woofer system is directly proportional to its cabinet volume and the cube of its cutoff frequency (the lowest frequency it can usefully reproduce). The obvious implication is that to reduce the cutoff frequency by a factor of two, e.g. from 40 Hz to 20 Hz, while still retaining the same system efficiency, you need to increase the enclosure volume by 23=8 times! In other words, to reproduce ever lower frequencies at the same output level you need an extremely large box!

However, box size isn't the only variable... You can continue to use a small box by accepting a much lower efficiency. In order to retain the same sound pressure level (SPL, meaured in dB's), though, this requires both a very large amplifier and a driver that can handle a lot of power and move a lot of air (requiring high excursions). Furthermore, it must be able to do so with minimal distortion. This is exacerbated by power compression, a phenomenon where the power heating of the driver's voice coil results in a non-linear relationship (read "distortion") between the electrical power in and the acoustical power out. Another variable not often mentioned is bandwidth... You can provide the perception of violating Hoffman's Iron Law by using a bandpass design, which can provide a lot of bass primarily across a very limited bandwidth. In all too many bandpass designs, the impressive bass is produced around a single frequency. This is often referred to as "one-note bass". It can rattle the furniture and impress your friends, and may even be OK for sound effects in action movies, but don't expect too much accuracy when listening to music with a lot of low bass content.

Summarizing, Low-frequency capability, box size, and efficiency form the three key aspects of system design. To increase any of the three, you have to give up something from the other two, with box size being the most sensitive. The often unpopular bottom line is therefore to plan on using the largest box you can comfortably live with. This partially explains the popularity of subwoofers, which can be both large and hidden from view, and often include their own built-in high power amplifier."

http://ldsg.snippets.org/appdx-a.php



Andre, I think you would be better off just cutting a hole in the side of your dad's garage and mounting this driver as an IB. Your neighbor's might have a different idea though.
 

Silver Member
Username: Magfan

USA

Post Number: 713
Registered: Oct-07
Andre seems bent on building the largest, biggest, meanest sub on the block....errr city? OK, the state! no, make that East of the Mississippi.

I have already suggested problems moving it, especially after hearing the project would require 2 @ 4x8 sheets of plywood.

Now, as to what to listen to? Obviously, Andre is considering a wildlife management career and wants to experience first hand 'The song of the Blue Whale' and the communications of Elephants.
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 2982
Registered: Dec-06
I will attempt to answer your questions

-Maybe I don't understand weighting.. I thought dBC just meant flat? No weighting?

-The studies I read show that low frequencies are not affected as much by age as high frequencies

On the subject of content content <20hz content, I've looked at at least one hundred 'waterfall' graphs and FFTs showing that it is very common in movies these days (this is not music only). As for music, it exists in some music and not other music, according to the graphs. Nine Inch Nails..rap..techno..not so much in more 'natural' music I suppose, although I think maybe orchestra contains a little from the symphonic bass drum, I should look that up.

-Now about the 'why' - I am planning on running it a few dB above the system and with a bit of a room curve to aid in hearing the really low stuff. My planned amp has been tested to handle 2000w at 20hz and frequency response was also verified. The subwoofer is designed with the rolloff of my components in mind.

-I don't like playing my speakers louder than 90dB average (if that), so this allows 25dB 'crest factor' for transients/peaks (shake the room and you) for the loud parts.

My ultimate goal is not to play the test tones all the time or invoke a weird feeling on purpose, but to play the movies/games/music with their full frequency range (even if it is manmade, it's there for a reason).

I understand infrasonics are like 'instinctive' in that they are scary as we may have used them in the past to sense danger. Well... we still do.

I wouldn't call this experimental; there are many, many people who have done a similar design and mine is no different.

I am aware of Hoffman's Iron Law and that's why the box is large, for extension and efficiency. I've modeled many small subwoofer designs that can achieve the output in smaller space, but it requires 10k watts, reserved for imax and without the extension.

Interesting enough, the way an IB works it tends not to 'propagate' as much (from the house) as the same driver in a sealed box or ported. It cancels a bit, but I'm not sure it's that much.

Hope that somewhat answers your questions and helps you understand my motives better, whether or not you agree. I am not really trying to argue, but one day I experienced an amazing audio system. Then I turned off the subwoofer (was crossed at 40hz) and the expanse and realism was much less, so I've always been wanting something to do that.

Next up is DIY speakers, as one of mine now ring in the tweeter and I also have uneven response which I need to work on acoustically.

Leo, I think city is about right :D And I am pretty sure I am west of the Mississippi (or am I?).

And as for a 170 subwoofer, it's not going to be too bad. 170 lbs is not too bad to move around in my experience, especially when two people are working together. It's when things pass 300 that it can get challenging.

Yes I will be listening to whale songs and elephants! Hmm.. I may listen to fireworks though..


btw I am somewhat interested in what Mags might sound like, as I have not heard any... Any descriptions or what?
 

Silver Member
Username: Magfan

USA

Post Number: 714
Registered: Oct-07
West it is! That takes up a lot of ground, too. Say, so does that sub you are building!
I believe the hi-power, low efficiency approach is one favored by Carver in his superjunior and other subs. But boy, are they tiny.

170lb can be inconvenient to move, awkward and just plain stubborn.

I saw a guy moving a fridge. He was using a bump strap and seemed ok until he got near the top of the stairs and IT GOT AWAY FROM HIM and ended up IN A SWIMMING POOL. I have no idea what 'plan B' was at that point. No graceful recovery possible, methinks.

Magnepans are clear, clean and quick. More discerning listeners than I report sub integration problems, in part, I suspect, because of the dipole design with the designed in phase issue. My solution is to cross over nearly as low as possible. I use about 40->45hz. I don't know the slope and the mains naturally are rolling off about that point, anyway. The field does indeed collapse when I turn the sub OFF. Pipe organ is right there. I have Camille Saint-Saens 3rd Symphony, 'With Organ' and there are peddle notes to 16hz. My sub is JUST capable of this at lower levels with no doubling. The panels are visually dominating and 'monolithic' to some. The smaller MMG model is less imposing and has most Magnepan virtues. Other opinions, such as Art's, do not find them convincing.
Can't please everybody! Magnepans are a DIY dream speaker. Crossovers, rebuilds of cabinetry, stands, setup and orientation are all endlessly debated. You should be able to score a pair, used and needing rebuild for low $$$. Even my factory rebuilt, 25+yrold MG-1s had a local buyer. (shipping can be an issue).

I enjoy my panels and intend a few changes. Jan gives me a head shake and a few things to consider. I listen, of course, proceed with caution, but am intent on a few improvements. First off will be new, wooden frames of better appearance.

Watch out for hi amplitude infrasonics. You can damage yourself, your house and create digestive problems in neighbors. I wouldn't be surprised if you could de-rat a house with a sufficiently ambitious application of such sound.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 14288
Registered: May-04
.

I can't help you with "dBC", I can find no reference to that nomenclature. Where did you find it?

Weighting systems were developed to skirt actual performance of components. Many cassette decks relied on various weighting systems to obtain their specified performance. MP3 is in essence a weighting system saying you cannot detect certain sounds due to masking effects.


High frequency loss is more severe than low frequency loss as we age. Some of the differences in low frequencies may be attributable to the physiology of the ear/brain connection relative to low frequency perception in younger individuals, yours is still forming or just recently has begun to slow while mine is in decline and has been for decades.


"On the subject of content content <20hz content, I've looked at at least one hundred 'waterfall' graphs and FFTs showing that it is very common in movies these days (this is not music only). As for music, it exists in some music and not other music, according to the graphs. Nine Inch Nails..rap..techno..not so much in more 'natural' music I suppose, although I think maybe orchestra contains a little from the symphonic bass drum, I should look that up."


While the low frequency extension might exist in films intended for specific formats (IMAX) it is unavailable to you in any home playback format. Check the frequency response specs on your player. Same thing applies to any music you can source no matter what the artist claims. Place "frequency of musical instruments" in a search engine for your answer to the bass drum.


"My planned amp has been tested to handle 2000w at 20hz and frequency response was also verified. The subwoofer is designed with the rolloff of my components in mind."

That is, like all static measurements, taken with the amplifier attached to a purely resistive load resistor. Since most load resistors cannot deal with 2000 watt input, most figures above, say, 400-500 watts are done strictly on paper. These on paper numbers have no relation to real world conditions any more than a 250 watt x 5 HT receiver would have a chance of accomplishing its specs. You forgot to include the non-existent sub-20Hz signals from your source player in your subwoofer calculations.


"I don't like playing my speakers louder than 90dB average (if that), so this allows 25dB 'crest factor' for transients/peaks (shake the room and you) for the loud parts."

Fine, you'll have some headroom because you won't find 25dB of dynamic range at 20Hz on any digital source I'm aware of.


"My ultimate goal is not to play the test tones all the time or invoke a weird feeling on purpose, but to play the movies/games/music with their full frequency range (even if it is manmade, it's there for a reason)."

Yep, but "manmade" stops at 20Hz from a consumer digital source. Check the specs.


"I wouldn't call this experimental; there are many, many people who have done a similar design and mine is no different."

To which one, if not both, of your parents should have reminded you that many people die each year from doing not too bright things. An "other people do it" excuse is pretty lame, Andre.


"Interesting enough, the way an IB works it tends not to 'propagate' as much (from the house) as the same driver in a sealed box or ported. It cancels a bit, but I'm not sure it's that much."


All subwoofers cancel at some point. Structural rigidity is normally the cause. Wavelength is too long and pressure too great. You're relying on those on paper numbers again.


" ... one day I experienced an amazing audio system. Then I turned off the subwoofer (was crossed at 40hz) and the expanse and realism was much less, so I've always been wanting something to do that."

No doubt low frequency extension is a good thing for the feel of the venue. However the extension that matters is not into the infrasonic range. A subwoofer that manages 25Hz cleanly will give a far diferent impression than one that stops at 33Hz. You still are ignoring the fact the system you heard is unlikely to have been capable of low frequency response beneath 20Hz simply because there is no source player available to the consumer that can reproduce such information.


Like you, Andre, I'm not trying to argue the point. I'm just trying to point out a very basic flaw in your calculations upon which I see you relying far too much.



.
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 2983
Registered: Dec-06
Leo, the thing about Carver's subs is that they don't have the extension AND efficiency, but NORMALLY it's not an issue. I just don't want to ever have to wonder if I should have gone for a little deeper, a little more headroom.

If I model a 10" driver in a 14" cube (external) I can achieve 120dB (quarter Pi space) from it... with 2400 watts... to 24hz (I have to rely on calculations as I can't easily verify it) at linear excursion... don't even talk about power compression. (This would likely cost about $700US to achieve with great results, except compression, a bit more than my passive build here).

Luckily the carry from the garage to the family room is not far, only through the yard to the back door and inside a few feet. :-)

I hope to hear some Mags, just so I know, at least, what they sound like (dipole).

I don't plan on playing infrasonics at high volume and then standing in a high-pressure area in the room to get blown apart :p If I do, I'll get bored of it and just enjoy it later.

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

Jan...

I found dBC on my SPL meter that I threw away a long time ago (broken and apparently could not fix?). I looked up C-weight though and it showed it rolling off at low and high frequencies, maybe 3dB loss through 10-20hz. I try to avoid Mp3, by the way. But.. a lot of stuff I hear is in that format. Sometimes I wonder if radio stations use them sometimes or if they are required to have a HQ copy. I wonder...

"...it is unavailable to you in any home playback format. Check the frequency response specs on your player. Same thing applies to any music you can source no matter what the artist claims. Place "frequency of musical instruments" in a search engine for your answer to the bass drum."
Blu-Ray tests confirm it is on there, and I am getting it soon (we have to eBay/craigs/whatever a lot of stuff that we don't need anymore before we can change our layout). I have not tested normal DVDs, but I have watched movies and noticed a lot of cone movement that I can identify as low teens in frequency, and they are STRONG, like War of the Worlds! I've done a lot of examining what certain frequencies look like and it is certainly that LOW. In fact some are below 10hz at HIGH levels. I almost worried about my speakers.. Actually, I have recently opened one up and examined it, finding that the driver has a 'bottomless' design and the suspension stretches when limits are pushed, so I am somewhat safe, at least mechanically.
For the bass drum, their fundamental is usually in the mid-upper 20s and can be a little below 20 or above 30 depending.. on the drum. More about the extension of my signal chain. I find that the voltage from a 10hz-100hz sweep started out about 1.4v and increased to 2.8v going up. So that's a 6dB fall-off to 10hz, mostly back by 25hz. That is about what the design is aiming for, and my room gain (8000 cubic feet total space to fill) should make it about right. If not, I've got a soldering gun, an op-amp, and some components, or I can buy an EQ and get my room fixed up as well.
"Since most load resistors cannot deal with 2000 watt input, most figures above, say, 400-500 watts are done strictly on paper. These on paper numbers have no relation to real world conditions any more than a 250 watt x 5 HT receiver would have a chance of accomplishing its specs. You forgot to include the non-existent sub-20Hz signals from your source player in your subwoofer calculations."
Ahh, this guy is a good amplifier tester, tested quite a few amps. He uses a VARIAC (that's one deviation from real-world sag conditions, stiffer circuit I guess helps), an oscilloscope, and other fun equipment. The 'load' is basically slabs of metal in multiple buckets of ice water (no reactive loads here) that he can connect in different wiring configs. His findings are that this amp's circuit breaker blows after a few seconds of brutal 4-ohm bridged sine waves at 2000 watts. It does fine for a LOT longer at 8-ohms (which is my planned ending config) for 1300w. The transient nature of music, if I'm crazy enough to really go that loud, means it will be fine for sub duty in a home. It's certainly no live venue! Factor in the reactive load, line sag.. I'd say maybe worst-case of about 1500w 4-ohm, which is still plenty, or 1000w 8-ohm. :-) My circuit breaker certainly won't mind a varying load that peaks at twice the breaker rating intermittently.
"Fine, you'll have some headroom because you won't find 25dB of dynamic range at 20Hz on any digital source I'm aware of. "
Right, although movies can be pretty demanding. Music? Nah.
"...is pretty lame, Andre."
Yeah, I suppose it is, if you put it that way. I've looked at many builds and their reactions when they first heard them, so it's not JUST because they do it.
{"All subwoofers cancel at some point. Structural rigidity is normally the cause. Wavelength is too long and pressure too great. You're relying on those on paper numbers again."}
A non-leaky sealed box tends to absorb and turn the inner sound into heat, while I believe an IB in-house tends to cancel moreso outside the house because of the waves both leaving together. with a bit less heat. Kinda like sitting a woofer in free-air... Not as extreme, though. Paper numbers? Maybe words :p
{"A subwoofer that manages 25Hz cleanly will give a far diferent impression than one that stops at 33Hz."}
Right. My last one didn't do much below 33, although it was there. So I know I'll at least get that much out of this, if not an octave and a half more.

Is the basic flaw the lack of material that contains it? Sure, a lot of material doesn't, but simply measuring my system shows that it shows up from the amp's outputs. And when the material does contain it, I know I'll be able to reproduce it. Pipe organs are probably the most valid musical thing it is good for. More headroom and more extension also usually means lower distortion.
A smaller sonosub with a lesser driver (smaller and less xmax) showed performance way above and beyond any subwoofer on the market, simply because they have to compromise with size and efficiency. It can achieve 110dB with minimal compression, and the 115dB pushed the driver excursion, but had minimal compression. He runs a 30 second sweep from 100 down to 10hz, so the compression will show up a lot worse than with a movie, especially if it can handle hundreds of watts for 30 seconds. It has low 1-4% THD at normal levels all the way down to 18hz, and under 10% on the 110dB (still owns commercial). The group delay is low and the spectral decay is fast (= NOT BOOMY).
I know they're just numbers, but it should show that my sub is certainly overkill for my application = low distortion, high headroom along with deep extension, which was my design plan. It may be a vented design, but the vent effects will only be of any importance below 25hz.
He tests many subs the right way, outdoors ground plane far from other boundaries. This sub lived up to its design purpose, and so should mine. My only concern will be making it work with the room. I have a nice program I can use for that... free from the DIY community for everyone.

I try to give detailed responses, but sometimes I veer off my intended topic...for a while...

If you wish, I can provide some links to these things I mention, but don't show or reference to.
 

Platinum Member
Username: Nuck

Post Number: 14272
Registered: Dec-04
Maybe it's just me, but I feel like Andrew is our own fire-hall puppy and we get to watch him grow up.

Keep learning, Andre, question and try.

Now about the garage...

http://www.freewebs.com/movie_pix/Back%20to%20the%20Future/giant%20speaker.JPG
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 14289
Registered: May-04
.

OK, Andre, you've convinced yourself. Go build it.

I am amused you can count/observe 12-15 oscillations of the driver per second though.


Just put me in the "seen it before" column.


.
 

Platinum Member
Username: Nuck

Post Number: 14275
Registered: Dec-04
JV 12/30/09

these memory things are getting smaller every day...
 

Platinum Member
Username: Nuck

Post Number: 14276
Registered: Dec-04
Have fun Andre, in the worst case you might end up at 22 or so as a bass amp.
Or your tuba.

http://media.idahostatesman.com/smedia/2009/03/10/13/608-Opus_Croakus.standalone .prod_affiliate.36.JPG
 

Silver Member
Username: Magfan

USA

Post Number: 718
Registered: Oct-07
Andre,
I'm declaring a winner:
http://www.youtube.com/watch?v=o36Kp6veJ6c&feature=related

This should satisfy even the MOST bass hungry.
 

Platinum Member
Username: Nuck

Post Number: 14280
Registered: Dec-04
The military will use this, lowered from a Sikorsky, to physically disable an opponant and his ability to communicate.
I like the avalanche and weather testing abilities as well.

U2 has one of these on the 360 tour?

It seems a bit uni-directional, however... and 20Hz is as low as the source goes anyhow? hehe

There is frequency response, then there is industrial usage.
Remember the Tacoma narrows bridge? Focus on one harmonic frequency and see what happens.
http://www.youtube.com/watch?v=P0Fi1VcbpAI

Even numbers and primary, secondary and tertiary frequencies are bad news.
Ever wonder why the fan on an old alternator has uneven blades?
 

Silver Member
Username: Magfan

USA

Post Number: 719
Registered: Oct-07
What did the guy say?
95->105db / 20hz / 250 METERS?

And did you see the bank of amps the guy was wiring up?

This is why I warn Andre about infrasonics at hi amplitude.

The military will use this, lowered from a Sikorsky, to physically disable an opponant and his ability to communicate.

I believe that is a euphamism for KILL.
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 2984
Registered: Dec-06
I've seen that video before, and it's funny how you guys are reacting :p

Yes, I convinced myself a long time ago about this. Besides, it'd be kinda hard to return all the stuff now anyway if you convinced me :p

This is for maximum fidelity, including realistic volume levels. Your speakers/sub may satisfy you, but I am certainly not convinced I'm in the recording studio/ mixing theater yet. I understand the subwoofer systems they use in studios and theaters are not sub-20hz.

However, the name of the game is overkill here..

..great for scaring people at halloween.

I'll get back to you with my impressions when it is built.
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 2986
Registered: Dec-06
Upload

Here is the low-range response of my front speakers from where I am sitting listening to "Oh, what a night, late December, back in '63..." at this very moment. I used 1/12 octave smoothing smoothing which removed the nodes that were high Q which went like 40dB down.

As you can see, my current response drops off below 45hz, and then isn't of much use for anything below 40hz.

I don't trust this microphone as it is not calibrated, so I may later post a more accurate measurement when I get an SPL meter which I can use a calibration file with.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 14296
Registered: May-04
.

I don't believe I've ever seen anyone measure in room frequency response using music.

Don't you have a sweep generator, Andre?


I know you're intrigued by these numbers and on paper calculations you've been performing but, Andre, they don't mean much. That's the message you'd get from just about anyone on this forum should you come to us with a measurement and ask us what we thought of the component based on the measurement or on paper spec. Maybe you just need to get through this on your own but, IMO, you also need to step back and look at the bigger picture.


From your "How amps work" thread;

Posted on Tuesday, June 17, 2008 - 09:43 pm:


"This explains one of the reasons why my newest receiver has much better low-end response than my old one. The VA rating on the transformer is almost 3x as high and the PS should be stiffer (less sag). The lower impedance at lower frequencies in speakers will require more power and bass usually has the biggest transients and so the quality of the power supply can determine the quality of the bass response. Surely there is a lot more to it than that, though.. "




That's why I often suggest you ignore the on-paper specs and buy the heaviest amplifier you can afford."



Remember?


Your enthusiam is overtaking your thinking.





"Your speakers/sub may satisfy you, but I am certainly not convinced I'm in the recording studio/ mixing theater yet."


And we wouldn't expect you to be convinced. As a matter of fact, we'd all probably have tittered quietly to ourself had you said you were. I know you're enthusastic and that's great, I know you see the numbers as promising something you can achieve and to a certain extent they do ...


But it's not the numbers and it's not the overkill build that will finally convince you, Andre. What this project offers you is learning that fact alone. Learning is what this project offers. You have wanted final results right now from the day you showed up here, Andre. You wanted to build the best version of the headphone amp instead of building an amp and then learning what the better version offered piece by piece. You're still very young and that means a lot can be overlooked but you need to get a grasp of this whole thing as a learning device. You learn by doing and mostly you learn by screwing up and figuring out how you screwed up - not just expecting everything to be the best all at once. You learn by hearing what two watts can achieve compared to two thousand.

Maybe you've not heard us repeat Nelson Pass' motto, "It's the first watt that counts."


Tell me, Andre, what would convince you you are in the studio? What do you think will do it?


Is this guy you mentioned who tests the subs and amps willing to mentor you or is he just selling stuff?



.



 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 2988
Registered: Dec-06
Okay, first of all, I took the measurements using a program using RoomEQWizard, and it uses a swept tone to to calculate response, spectral decay, impulse response, waterfall graphs, etc..

Yes, I remember that, and I understand there is a difference between paper and real life, but in my opinion they are closely related as long as there is enough information.

If I had the money to experiment, I would be doing small projects first. I just have trouble waiting forever.

2 watts!? For me to achieve enough volume with that extension, I would need a LOT of drivers to get that efficiency!

I feel like I have learned quite a bit just from what I've done over time. I've built a couple small 'speakers' although they weren't great, but all they did was verify what I've learned on paper.
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 2989
Registered: Dec-06
I am having a lot of problems with this computer, so what I wrote got messed up, but.. anyway..


To be convinced you are there, there has to be a lot of phase information intact, the same response as the system used for mixing, lots of sound dispersion patterns, especially high frequencies.

My room acoustics and speaker placement does not do well with this. More channels helps more with phase and HRTF information.

But right now, I'm building from the bottom up, or trying.

I am planning on building a Left, Center, Right speaker next, and using my current speakers as surrounds.

There are a lot of problems with the average acoustic environment for speakers,


An important thing about headphones and binaurally recorded audio is that the phase information is restored. The problem then is the headphone response and the microphone response and the difference of the dummy head used for recording compared to my own, etc...

I know I am leaving a lot of information out, but I've heard stuff that definitely correlated with measurements I have taken, and until they don't, I am going in that direction.

He does not test anymore. Subwoofer Tests - Archived
 

Silver Member
Username: Magfan

USA

Post Number: 731
Registered: Oct-07
Rives audio sells a test CD which is 'calibrated' to the RS analogue meter. The RS meter has a known rolloff curve for which the Rives disk provides the 'opposite'.

Simple solution, but not computerized/automated. You'll have to do it the 'old fashioned' way and manually take the data!
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 2991
Registered: Dec-06
I am aware of the test CD :-)

I just don't have the meter.. that is the problem. Plus REW has a calibration file for the RS meter, and it compensates for it.

My old meter died. As soon as I get a new one, it will be accurate.

BTW I did a second test with my surrounds on and it caused a bass hump 50-60hz, a null at 45hz, and it rolled off the same.
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 2992
Registered: Dec-06
It snowed today, but tomorrow I am planning on continuing cutting (outside) the circles. We have 2 32" circles left, and then we have to cut the driver/port holes. Then we paint/sand and drill binding post holes. (The we refers to the father/me).

Pictures have been hard to come by..
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 3003
Registered: Dec-06
I have been working on gluing/sanding today...

This is a partially completed bottom end cap.

Upload

Sitting on the kitchen table.. that hole is a small mistake that will not be a problem or seen in final construction. Relative to the table, I think it looks kinda big...

The driver will end up mounting there. You can trust my dad to take an OKAY picture...
 

Silver Member
Username: Magfan

USA

Post Number: 762
Registered: Oct-07
Andre,
Ever heard of these?
http://www.audiogon.com/cgi-bin/cls.pl?homesubw&1266003849

Lookin' good so far.
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 3004
Registered: Dec-06
I find it difficult to remember, but it sounds really familiar.

Four would certainly be sufficient for just about anything, except giant rooms.

We've drilled a bunch of holes since then, as well as do a lot of testing/tweaking to get it right.

We should be able to paint tomorrow, assemble, glue (maybe Friday), and then find out what I've done! As long as I haven't missed anything...
 

Gold Member
Username: Mrskullz1

New York

Post Number: 1341
Registered: Feb-07
post pix!........now! lol
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 3005
Registered: Dec-06
I am about to. I have some, and I finished, but I will get back to you later. In fact, it may already be up by the time you see this.
 

Gold Member
Username: Mrskullz1

New York

Post Number: 1353
Registered: Feb-07
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 3006
Registered: Dec-06
I am back (after some time!) to add some comments about this.

Pictures, then information.

Upload
Upload
Upload
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I apologize for the small pictures and cell phone quality.

The last picture there is the response from its current spot in the back right of the room before I raised tuning and tweaked the inside with more absorption.

I will be back to give information about all of it in a bit.
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 3007
Registered: Dec-06
Back..

It took me a while to get all the measurements and try many positions. This one turned out the most even response. The response you see up there is worse than it is now. Now it's less of a peak and less of a dip.

I am working on getting an equalizer. Even in my current state I still can't turn it off.

The final sensitivity seems to be 6dB shy of what it should be. I am looking into it.

I also got a blu-ray player and an HDMI cable in the past week. It turns out that using Dolby TruHD and DTS-HD adds a life-like quality to the sound which is most evident during low volume (higher bit depth).

It's certainly not done yet, but I am getting there.
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 3016
Registered: Dec-06
I got rid of the HDMI cable soon after because of a problem I had.

I ordered a parametric EQ for the sub which should be here within the next couple days.

I found that the driver specs have been changed by the manufacturer. When I ordered this they weren't out, but my measurements seem to support that I got one with the new specs. If so, that explains why I am having these problems.

It also means that if/when I go to build the other sub, I'll need to use a different driver. It will either be the SS Rl-p18 or the Fi IB318.

They are about the same I would say, except for enclosure requirements, so I will likely opt for the Fi since it is half the price. My enclosure is in between the optimum for both of them and I might as well use the same brand.
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 3017
Registered: Dec-06
It actually sounds OK now, but it is still not what I'm trying to achieve.

Here are the before/after EQ

Upload
Upload
This is the current spot and EQ (funny enough, the first spot I ever had it in was the best spot). The sub has an infrasonic hump, but I decided I'd rather have it than not.

I did not have to use a whole lot of EQ, no boosts, only cuts. The spot where the slider (blue) is on the graph was actually a cut that was too strong in the receiver.
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 3018
Registered: Dec-06
I ordered the amp the other day, should be here soon.
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 3019
Registered: Dec-06
Update..
The results were an increased output level, of course, but I had to a lot of experimenting. It sounds pretty good now, I would say.
I was playing Stone Temple Pilots - Dancing Days and saw the clip lights flashing (2000w 4-ohm), so I know what the limits are. I see them flash at times.

I have found its power handling at low frequencies is questionable. I am thinking I need to improve the enclosure (weight, solidify) as it shakes up and down a lot with loud low frequencies.

The SPL is very lacking for what it is, so I need to look into it. I don't pass 104dB at LP, but I have read 118dB at a room mode (27hz) in the corner.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 14952
Registered: May-04
.

Don't stand in the corners, Andre.
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 3020
Registered: Dec-06
I couldn't if I tried. I just reached my hand out with the SPL meter over the stuff that sits in the corner.

From my observations, I may have to build a second enclosure. I am watching Star Wars for the first time tonight and tomorrow (yes, I know). I am watching all 6 together. On many explosions, the amp clips. I watch at -20dB on the receiver and I had to reconfigure EQ to keep nasty sounds coming from the sub (i.e. drop 30hz 6dB).
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 14961
Registered: May-04
.

You think a second enclosure is going to stop the amp's clipping? Why?
 

Gold Member
Username: Magfan

USA

Post Number: 1288
Registered: Oct-07
Maybe Andre is talking about evening out in-room response?
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 3021
Registered: Dec-06
Yes, I am talking about evening the response.

However, I have other things I need to try (such as renting a pro sub to see how mine compares in the intended frequency range).
 

Platinum Member
Username: Nuck

Post Number: 15134
Registered: Dec-04
Andre, do you trust the driver and amp to do that advertised #?

I think the driver circuit is not nearly as responsive as advertised.
Not hardly.
I hope the next one is a proven unit for you.
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 3022
Registered: Dec-06
I know for sure the amp is capable of 2000w into this driver.

Everyone else I know of that has used the driver has not had problems. I'm pretty sure it's an enclosure thing. I wish I had more experience with this kinda stuff.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 14971
Registered: May-04
.

Well, Andre, this is how you gain experience, eh? Some day you'll be the old dog/fast gun on the circuit and everyone will come aiming for you. For now, just think, Andre, think. Computers don't lie, people just input the wrong information. Garbage in, garbage out.

Oh, and I don't know of a "pro sub" that actually extends down to 11Hz real world.


.
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 3023
Registered: Dec-06
No, the pro sub would be to reinforce 25hz+.

I really cannot say much else. My psyche is unstable enough as it is, maybe a bit volatile as well.
 

Gold Member
Username: Magfan

USA

Post Number: 1296
Registered: Oct-07
Andre, if something isn't going to plan you can fold or you can react in a constructive manner.
Check your assumptions. Check your calculations. How much fudge factor / Kentucky Windage did you use? Is your power line to the amp 'stiff' enough to support 2kw out? Have you measured the power line voltage and checked? Do you have a Kill-a-Watt plug in meter?
Is the enclosure built to spec? Any air leaks? Proper size? Any way to measure some driver parameters? You'll need some place free of boundaries to measure the driver.
Plenty of time to be unstable......later......
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 14972
Registered: May-04
.

Lesson number one, Andre, most important when you're sticking your hands into something with voltage and current around. You get nowhere being unstable or volatile. Keeping a cool head while seeing the big picture is what's going to answer your problem. Being volatile will only cause more problems, some of them disastrous. Lesson number two, if things ain't working out the way you planned, throwing more money or more watts at the problem usually isn't the answer.

You're certainly not the first person to get frustrated by their initial experiments. And that's what this is, Andre, this is your first big thing. And you bit off one hell of a big chunk for your first go'round. If it didn't turn out quite as you'd like on the first try, join the club. Most anyone who has tried stuff has a closet or an attic or an entire garage full of the stuff that didn't turn out the way we planned. It's learning that counts here even if you find you do have to build another enclosure. Don't miss the point of this whole experiment. If you keep your head together and think about what you wanted to accomplish and what you've managed to do so far, then you can reach one of those great "Aha!" moments. But nobody hands those to you on a platter, Andre, you have to really work for them and you have to develop the ability to link things together as you gain that experience you wish you had right now. Like anything worth doing you take a few steps forward and then stop, step back a few steps, get frustrated at your lack of progress and knowledge and then try again, this time with more focus. And with more coolness, not anger. Maybe it'll be a year before what you want to know right now comes to you and it'll be in other experiments. It can't all come right now, that's just the way things are, Andre. Learning is made of building blocks that you stack on top of one another and then take apart to look at each one and put them together again with a little more skill and ingenuity and a few more little links that hold it all together like glue that you discover each and every day. And, if you're really intersted in something, that goes on for the rest of your life. But you don't let one goof up throw you into the toilet. You're what? fifteen now? Andre, you could have a good eighty years of frustration ahead of you or you could have another eighty years of learning, finding out "stuff", to do. You get to decide which it is but any of us here can tell you which is the more productive.





.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 14987
Registered: May-04
.

http://www.tweekgeek.com/_e/DSpeaker/product/Anti-Mode-8033/Anti_Mode_8033.htm
 

Gold Member
Username: Magfan

USA

Post Number: 1324
Registered: Oct-07
Based on connection, useful for single sub installations.
Multiple subs? TBD.
for the asking price, pretty substantial!
 

Gold Member
Username: Arande2

Rattle your ... Missouri

Post Number: 3024
Registered: Dec-06
Hmm well my response is pretty flat.. The EQ is used more for a bit of a rise with lower frequency.

I am lacking motivation to work on it right now, but I'll see where it goes.
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