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8w7's: The Advantage of Running 8's

 

Silver Member
Username: Fishy

Tamarac, FL USA

Post Number: 334
Registered: Sep-04
Are there any? My 10w3's seem "snappier" than most of the 12's I've heard which seems to go better with the type of music i listen to.

Why don't we see more large drivers in high end home stuff? Is it a directivity issue because floor standing woofers play higher frequencies than dedicated subs?

Was just wonderinhg what 3 8w7's would sound like off an Xtant 1001dx at 333 watts each. They're rated for 300 and I know that amp is underated at 1000 watts. Would it kill em?

thanks :-)

-Fishy

 

Gold Member
Username: Jonathan_f

GA USA

Post Number: 2051
Registered: May-04
If you are careful you won't kill them. It never hurts to have too much power IF you're smart enough to utilize it well. With the low moving mass, the 8s would be very responsive, but down low they won't impress that much or in SPL. 3 8W7s would give a pretty good punch, though. An actual home audio subwoofer is typically larger than car subs, you'll see 15's, BUT the home audio subwoofer is actually a SUBwoofer, it's not intended for audio as much as it is pure rumble. Most home audio cabinets don't need as large of a driver b/c the cabinets can be larger, thus lower tuning if ported or transmission line enclosures can be used. Plus, you're guaranteed the proper enclosure size in home. I personally think the home audio philosophy should also be applied in car audio more often, large drivers up front that can drop very low, and a subwoofer that's intended more for power output and rumble than it is for producing audio. In a car, it works well b/c the speakers transition well, and since your subs are behind you, generally the lower you can crossover, the better. For example, my Dynaudio 8" mids don't have any trouble going down to 40-50 hz in most cases (unless its a really overdriven rap song, etc., but that's not my preference of music, anyway, they can handle it, but the SQ naturally isn't quite as good), I could have used a 15" sub ported and tuned low for a nice output and great sound quality. Of course, my truck couldn't fit it.
 

Bronze Member
Username: Jamesdunn

Post Number: 32
Registered: Sep-04
its not the watts that kills a speaker or a sub it distoion that kills them just keep distoion to a min. and youll be fine. about the diff. in the subs i dont know.
 

Bronze Member
Username: Jamesdunn

Post Number: 33
Registered: Sep-04
LOL Jonathan posted at the same time as me.
 

Silver Member
Username: Fishy

Tamarac, FL USA

Post Number: 335
Registered: Sep-04
I dunno about that credo. If the RMS rating is thermal then if you apply a CONTINUOUS amount of power greater than that rating for certain period of time you can melt the voice coils. Luckily music in general is transient, but I don't think I'd want to play a 350 watt test tone thru a 8w7 for very long.

I always thought the reason distortion killed speakers was because it creates a non-harmonic signal. A speaker cone doesn't like "clipping" :-) along to the tune of a square wave. I also always assumed distortion resulted in more mechanical destruction than thermal.

-Fishy
 

Gold Member
Username: Jonathan_f

GA USA

Post Number: 2054
Registered: May-04
It's clipping that usually does it, a square wave b/c it forces the speaker to high excursion and holds it there longer than normal, and since it's not moving, heat builds up in the voice coil. Of course, clipping creates extreme distortion, which can be damaging, but it's mainly the heat buildup. Distortion is in music, such as distortion pedals used on guitars. This is to an extent(clipping I mean), if you put even a clean 400W RMS on a 100W speaker for long enough I guarantee you will fry the voice coil. Simply too much heat buildup due to the amount of current flowing. In most cases you can actually be safer by going with twice the power compared to the rated power(read: IF you're smart enough to use it and don't run it full blast). Amps go into clipping more often than most think they do, properly setting gains and keeping the volume below that point doesn't guarantee that your amp won't clip. The signal WILL momentarily overload b/c of music dynamics, and if your amp doesn't recover well from clipping, it can be damaging. For example, assume you're listening near the amp's full capabilities, and suddenly the amp gets an overdriven signal, and it clips. High distortion and more power than if it were a smooth sine wave, potentially damaging the speaker if it happens too often, and the smaller amp will strain a lot to produce that level of power, and won't do it as effectively as a more powerful amp running at the same level. Now get an amp that is capable of twice the power and run it at the same level, it will have a lot more headroom and likely will not clip or the clipping will be VERY minor compared to the smaller amp. It simply has a much higher dynamic range at that point. While the speaker might still get a tad more power than it's rated for, it's not really that damaging, (and sounds a lot better) especially compared to the smaller amp that went into hard clipping. This is why I believe the Richard Clark test is true, but not necessarily the best way to choose an amplifier b/c it doesn't account for how an amp performs at clipping levels, which WILL happen eventually at most people's listening levels, especially in a car where you need more power to account for road noise, etc. If a poorly designed amp goes into clipping, it will clip HARD and recover slowly, worst case scenario the rails will stick and you'll get a very bad result. I also believe this is a major contributor to that traditional "tube amp" warm sound, aside from the types of distortion the amps produce when compared to each other. Tube amps clip more softly and smoothly than a transistor amp.
 

Gold Member
Username: Jonathan_f

GA USA

Post Number: 2055
Registered: May-04
warm should have been in quotations, not tube amp. typo
 

Silver Member
Username: Fishy

Tamarac, FL USA

Post Number: 336
Registered: Sep-04
Yeah Jonathan, since I only have 5 1/4 components I was hoping the 8's would match up better for mid bass(I'm into drum hits, HARD ones), but if smaller drivers match better because of a directivity issue then that setup won't help. An array of 3 8's is gonna have a lot more directivity than a single 12 or possibly a pair of closely spaced 10's(btw, is there some rule for distance between drivers?).

If its a phase issue, which I don't completely understand, then maybe they would help.

I don't know what I'm gonna do about my midbass problem. I don't wanna cut up my doors and the guys at Sound Advice(tweeters) told me the 6 1/2 Q's would fit then later told me "no way" when I came to pick up the truck after my 6 1/2 Q install. They went ahead and put the 5 1/4's w/o tellin me in and managed to convince me that was all I needed. Then to make matters worse I later find that the expensive speaker wire I gave them to run from a 700 dollar amplifier to 900 dollars worth of f/r components which I had purchsed from THEM was hooked up TO THE FACTORY WIRING HARNESS in the rear of the vehicle. I actually worked for these guys in mobile sales for a few months during the Christmas rush and liked the install guys I had, but the guys at this store were TARDS or in a whole lotta hurry, one of the two.

Well what can I do? needless to say I'm back to doin my own installs now. I'm stuck with the 5 1/4's up front but was thinkin about puttin some JL 6w0's in the back. I've got .16 cu ft boxes in the rear(in stock locations) with another set of 5 1/4 components. I just put that soundstream class A 50 in and have it bandpassed into those rear 5 1/4's 80-150 Hz(wanted to go higher but didn't have a higher Xtant sip). Sounds pretty good I just can't get alot of volume out of them. Those 6w0's look pretty good on winISD in .15 cu ft so I was hopin to drop them in there and sell/give away my rear components and maybe go with an Xtant 1.1i later.

I've got my front Q's crossed over 80 Hz at 24 dB/octave. This seems to be the best compromise between midbass response and door rattlin. At least I think its door rattlin it doesn't really coincide with volume as much as specific frequencies. I've soundproofed the doors once and am not really sure adding another layer would help. I can raise the crossover points(s)(ppi frx456 and onboard Xtant 4180c = 24 dB/oct) and solve the vibration problem but then the my front soundstage sounds "lifeless".

Just wonderin if those 6w0's would help out, them bein in the rear and all.

Thanks

-Fishy
 

Gold Member
Username: Jonathan_f

GA USA

Post Number: 2061
Registered: May-04
The 8s would have better midbass transition than the 10, but there is a rule for that. Usually, above about 80 hz the bass starts to "localize" basically you can point out where they're coming from, of course it depends on your ears. Sorry, just the truth. There really aren't phase issues with using 3 drivers IF they're wired in parallel, but every time you wire a subwoofer in series, a phase shift of 15 degrees occurs b/c of the inductance and reactance of the voice coils, and b/c it's a series circuit and a chain rather than all of them getting the signal simultaneously. Meaning you may lose bass response. The 8W7s would be better than the 6W0s by far. Best option is to consider more sound deadening(and doing a spot test to see where the rattle is) and using a more shallow slope crossover or lower crossover point. Another option (better IMO) is to consider custom kick panels if you have the space to do it. You can get better midbass and a more focused center image, so you gain the best of both worlds, and no rattles. Fiberglassing isn't so bad once you get used to it, there are plenty of tutorials online and if you are patient enough, the effort required is MUCH MORE than worth it. Trust me :-) If you have a truck with really low kicks, though, it tends not to work as well b/c the image is so low and there isn't a lot of space for the soundstage to raise because you sit so high, not counting that a lot of the sound gets blocked out from your legs, seat, etc.
 

Silver Member
Username: Fishy

Tamarac, FL USA

Post Number: 339
Registered: Sep-04
It wouldn't sound good in my Explorer. I assume you wouldn't mount the tweeter way down there. I like having my tweeter and mids close together, plus I'm tall and my kick panels ARE low, at least relatively I think.

No, what I was wondering was if those 6w0's or any small sub/midbass driver would fill in the gaps well from behind. I'd think they'd do better than some rear firing 8w7's I already have the boxes back there and they sure improved the midbass from those 5 1/4's.

If its a location problem what about "kickpaneled" 6w0's or some other 6 1/2? Might get in the way of my emergency brake tho.

Oh yeah, I can fiberglass. Got a gallon of Goegeon about 5 feet away from me.

:-)

-Fishy
 

Gold Member
Username: Jonathan_f

GA USA

Post Number: 2067
Registered: May-04
Kickpaneled 6W0s would help out a LOT, much better than from behind. Midbass location isn't as important as midrange location anyway. And it would allow you to crossover the Quarts higher.
 

Silver Member
Username: Fishy

Tamarac, FL USA

Post Number: 342
Registered: Sep-04
Well nix that idea. My emergency brake is about a 1/8th of an inch away from the left kick panel and the inside is jampacked full of wiring. Hmmm, I wonder how hard and how expensive it would be to get some grey Explorer doorskins at a Junkyard. Mines a '96 and they made about a gazillion of them things.

I was kinda enjoying the "stealth" look. When I pull back my cargo coverer you can't even tell I have a system aside from the h/u. I had two pair of A/D/S 320i's in the doors of my Cherokee(sick midbass for 5 1/4's) with the tweeters and half the mids exposed. Didn't take long for them to get stole.

For the doors I guess I'd probably be better off with an Infinite Baffle mid bass driver(no room for box if I want my windows to go down and the 6w0 is down 2dB at 80 Hz and 3dB at 60 in a 2 cu ft box). Got any other driver suggestions? those JL 6w0's run about $80 each I think.

How much volume in the average size door anyways? or is it so leaky that its considered pure infinite baffle.

-Fishy
 

Silver Member
Username: Fishy

Tamarac, FL USA

Post Number: 361
Registered: Sep-04
Ya know with a lil work I think I can really get my system Bumpin.

;)

-Fishy
 

Silver Member
Username: Audiobahn_man

Freakmont, MI

Post Number: 151
Registered: Aug-04
I love how people talk like that, i like reading because the more knoledge you have about this, the less mmistakes you will make. Thankx for posting so i can read!!! AND LEARN!
 

Bronze Member
Username: Loudnobnoxious

Post Number: 76
Registered: Jul-04
all i saw was "distortion kills speakers" and I crapped my pants. This is an old myth like "bigger speakers are slower." It just never went away because people still believe it.
 

Gold Member
Username: Jonathan_f

GA USA

Post Number: 2139
Registered: May-04
There are a lot of audio myths out there lol.
 

Gold Member
Username: Jonathan_f

GA USA

Post Number: 2144
Registered: May-04
Just the other day I saw a post here saying you shouldn't play w/ your trunk open for too long b/c "the subs will get too much air". That's about the stupidest thing I've heard in quite some time.
 

Silver Member
Username: Fishy

Tamarac, FL USA

Post Number: 413
Registered: Sep-04
"bigger speakers are slower"

Is that the same thing as saying

"bigger speakers are less responsive"

If it is I'd like to know exactly why smaller subs(like 8's) generally do sound "snappier" and blend better with your components(midbass transition).

I know a good deal about acoustics and I can't figure it out. Does it have something to do with less directivity or is it that smaller drivers generally having lighter and stiffer cones.

Help me understand it. As I understand it Adire says that cone acceleration doesnt depend on mass because mass doesn't depend on time. That seems like BS to me. Its true that two cones of different weights moving at the same excursion at the same frequency have exactly the same acceleration, but music is not one constant Sine wave(s). It has transients and that puts a speaker in situation analogous to the linear acceleration of a dragster. Everyone knows that a lighter vehicle with the same power etc. will accelerate faster than a heavier one.

I don't get it.

-Fishy
 

Gold Member
Username: Jonathan_f

GA USA

Post Number: 2174
Registered: May-04
Adire's comparison doesn't show the whole scenario, but they did prove their point about inductance being important. They showed that a heavier speaker with lower inductance is capable of producing a flatter response than a lighter speaker with a higher one. But, I'd like to see them compare a heavy speaker with low inductance with a lightweight speaker with that same low inductance. That would show what affect mass has. Saying mass has nothing to do with it is just wrong. Once Adire makes a 15" tweeter I'll retract that statement. You'd think if mass didn't matter at all, the Brahma would use something a little stronger than a epoxy treated paper cone. Not knocking Adire, they make a killer sub. The biggest thing is that a heavy speaker is harder to control because of the higher moving mass, thus requiring stiff suspension to control it because of the inertia the speaker has after traveling some distance. Lightweight cones are easier to accelerate for the given power, and easier to control because of inertia. With enough power, you can make a bigger sub respond as quickly, but with the same motor design and power, response will go to the lighter sub. To say that mass doesn't matter is going against physics.
 

Silver Member
Username: Fishy

Tamarac, FL USA

Post Number: 416
Registered: Sep-04
Ok cool, I thought I might be going stupid.

-Fishy
 

Silver Member
Username: Fishy

Tamarac, FL USA

Post Number: 417
Registered: Sep-04
I understand totally why there's no 15" tweeters. Thats a directivity issue. The higher the frequency the higher the directivity.

You'd get really really really crappy off axis response with a 15" tweet, but could probably tear an eardrum if you stood right in front of it.

:-)

-Fishy
 

Gold Member
Username: Jonathan_f

GA USA

Post Number: 2176
Registered: May-04
That, and the fact that a 15" sub just plain out can't play that high accurately due to cone resonance and moving mass.
 

Gold Member
Username: Jonathan_f

GA USA

Post Number: 2181
Registered: May-04
BTW,
"I understand totally why there's no 15" tweeters. Thats a directivity issue. The higher the frequency the higher the directivity."
Sounds a lot like Electrostatic panels, doesn't it :-)
 

Silver Member
Username: Fishy

Tamarac, FL USA

Post Number: 423
Registered: Sep-04
Yeah but since they're usually "tall" they're directive vertically or in the "Y" direction not laterally or in the "X" directions. Round sources are equally directive in both X and Y, unless they're mounted in an array of course.

A cool thing about arrays is that you can actually "steer" that beam pattern for a specific frequency by adjusting the phase between the individual drivers.

I don't know how useful this would be in music(you'd have to adjust phase differently for each frequency to get a fairly coherent on axis beam pattern, a simple time delay wouldn't work), but there's some pretty neat sonar applications. Due to reciprocity this works equally as well for microphones or other listening devices. To listen for ultra low frequencies some subs(as in submarines :P) tow this huge retractable line array(in the thousands of ft I believe) behind them. I imagine they could beam steer the hell outa that thing.

:-)

-Fishy
 

Bronze Member
Username: Alpha_male

Post Number: 15
Registered: Sep-04
Jonathan- I know this is off topic and way over my head but I see that you mentioned somthing that I have been wondering. I am ordering a RE xxx12 and I am going to wire it to 2 ohms. I can get the dual 4ohm and wire it parralel or dual 1ohm and wire it in series. Would one be better than the other? If so, why?
 

Gold Member
Username: Jonathan_f

GA USA

Post Number: 2184
Registered: May-04
Parallel ideally, more voltage. Remember that in a series circuit, current is the same and voltage is split. Plus, dual 4 ohm allows more wiring options.
 

Silver Member
Username: Fishy

Tamarac, FL USA

Post Number: 435
Registered: Sep-04
lol, what could be more off topic than submarine towing a sonar array?

:-)

-Fishy
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