Three 8's
 

I've come to the point where i'm planning out what kind of system i want for the max, but i'm fairly new to the audio scene. I want something that will also be for show, and i'm pretty sure I want to use a similar set up as semy2k2go which can be seen here. I noticed though that JL discontinued the w6s in 8's so i'm stuck on which subs i should buy for this set up. Could anyone make some suggestions towards the few remaining subs that come in 8's that i could use for this setup? Or should i probably try a different setup with different size subs?

There is no reason to use several small subs. A single larger sub can do everything the smaller subs can do in less space and with less complicated wireing.

i think he wants to do it for show in which case i'd consider solo baric L7 8's but i would also go with 1 speaker, all depends what ur going for really

you could always go with JL's W7 line... pricey though.

Ya, show is a big concern for me here. Thanks for the response I'll check into them, but I might be leaning towards getting bigger subs since it seems more practical. Just need some more ideas for the setup. I originally had 2 12 audiobahns in a big ugly bandpass, and it resulted in no trunk space at all so i ended up just selling them before I even put them in (i was also pressed for money at the time).

you could try free-airs, if they are mounted propery and the baffle is nice and tight, im sure you wuold be surprised at the output. i loved my pioneer free air's. just a thought.

I think i've decided on getting 1 12" Kicker Solo-Baric L7 with the dual 4-ohm voice coil. What's everyones opinions on this sub? Will it get the job done? Also, what would be a good quality amp to go with it?

Actually, several smaller subs have more surface area than fewer larger subs in equivalent sized enclosures. Subs are all about moving lots of air. Ive heard incredable systems with 4" woofers.

Sorry, that is almost never true when comparing similar woofers. Such as same model of same brand but different size subs. Has a bit to due with the fact that most subs pistonic surface area is a circle. Also have to consider the wireing options involved in multiple woofer configurations versus single woofer configuration. And relative efficiency of larger subs is generally higher than the smaller subs. Even when 3 of say an 8 inch woofer will require less total sealed box volume than maybe a 12 inch model you still must consider the wall thickness into the equation for total box volume. Also consider that larger woofers normally have greater excursion and therefore more total volume displacement.

If you are restricted to a certain brand, then yes, a larger sub may be better. It all comes down to the specs of the drivers. I also agree that the multiples will be harder to wire, but you only have to do it once. Most good quality amps can push 1 ohm so your options are open. (In my day, it was hard to find an amp that could push 2 ohms without blowing up).
The efficiency, I think, is negligable. You typically cram as many watts into your sub as you can afford and run low frequencies. Efficiency isnt as critical in the lows as it is in the mids and more so in the highs.
Wall thickness depends on box design as well. With a large box for a 12, you need a lot of bracing or thick walls to give a dead box. With smaller drivers, the walls are alot closer and typically, no bracing is required.

"subs pistonic surface area is a circle"
I always thought those Kicker square subs were pretty interesting.

For true purists, I agree with jmax about a single sub being better than multiple, smaller ones.

But you want it for show, correct?

Why not go infinite baffle like nismos14 suggested. If you really want 3 8s, then try Oz Audio subs. I'm not sure what model, but Oz makes GREAT free air woofers. You can still fit your 3 8s behind the seats, will still have all your trunk space, and if you do your install right it will look great being able to see the backs of the speakers when you open the trunk. Just a thought. IB systems can sound awesome if done correctly.

Don't make any quick decisions. Research research research.

Tony

Cerwin Vega Vega 8's 70$
Resonant Engineering RE 8's 50$
Elemental Designs E8A 145$__HIGHLY RECOMMENDED
Tang Band TB8 - 32$

thats a very wide price range I gave you. None of those subs are free air.

I have 3 JL Audio 8w6's and I can guarantee they sound better than a single 10" or 12" sub. Who cares if its a bit more work in wiring them if the end result is something you will be happy with and looks the way you want.

i have a friend with 3 15"s in his Grand Marquis and my god is it loud :). you would definitely be happier with 3 8"s than a single 12" unless it happened to be something along the line of an Adire Brahma or JL 13W7, but powering teh brahma would be a nightmare and the 13w7 is a bit pricey. i would have to agree that for 8"s the Elemental Designs E8A would do you fine especially if you had them in the rear deck ported into the cab.

Hmmmm...be careful. I'm sure your setup sounds SWEET, but to say that a single 10" or 12" couldn't sound better is an awfully big gamble!

Tony

Well, lets just say that they provide a more full-range in SQ.

Oz is a good choice, adire, digital designs, audiomobile(o.o.b) elemental designs, image dynamics

Vegas would love to take your money on that bet. With subs it is pretty safe to say that anything an 8 can do a 10 can do better, anything a 10 can do a 12 can do better, etc.

Lets assume that (2) 8"s equal the surface area and displaced excursion volume as (1) 12". It doesn't, but its close.

Someone explain which will sound better and why. When I say better, I mean in terms of the reproduction of sound, not loudness.

I think that two subs will sound better than a single (assuming they are wired mono). You have to remember that car audio is NOT home audio. Interference is a non-issue (as it might be in home audio). It really comes down to pressurizing a trunk (or a cabin). My feeble mind sees two subs pressurizing an irregularly shaped trunk better than a single point source generating the sound waves.

Someone prove me wrong...

As you implied in a car it comes down to pressurizing the cabin. So the math, excursion X Sd = total colume displacement, is basically what it comes down to. Remember that most 12's use a different motor than an eight of the same make and model. The 12 will normally have greater excursion further increaseing the volume displacement. The shape of the trunk is irrelevant to how a sub or subs will pressurized the air. So long as it is an "open area". Narrow area's could turn into ducts or other more complex resonators. But the number of subs is irrelevent if the Vd is the same.

I am willing to bet that I have a single 15 that can displace twice as much air as your three 8's. And that it can do so with lower distortion. What is the combined Vd of your three 8's?

They're not my 8s...they're the author's :)


I think your 15 CAN outperform three 8s. Its got more surface area, and I would agree that it probably has much greater displaced volume. But I bet if your 15 was really a 12 like in the previous example, it wouldn't outperform (3) 8s, assuming identical area and displaced volume.


On another subject, I thought that large sub coils have a slightly harder time at keeping the woofer excursion "straight". Any thoughts on this?


Also, if a 15 displaces twice the volume as (3) 8s combined, and the woofers are all moving at the same speed (to replicate the correct freq), what am I missing? Because to me, if a 15 has twice the excursion length as an 8, yet its moving at the same speed to produce the correct Hz, doesn't it have half the number of cycles as an 8? Does this not have a noticeable difference in sound because it's cycle is just twice as long? I'm missing some piece of general speaker theory I think...

I don't have a 12 that I would like to use for that comparison. Otherwise I would gladly compare. But there is much more to it than volume displacement, that's only the tip of the iceberg.

The cycle is determined by the frequency of the sound being reproduced. A smaller driver will have to move further to reproduce the same low frequency note at the same volume. I believe going down in frequency one octave requires 4 times the excursion to achieve the same SPL. In other words a 40 hz tone at 90 dB, if that requires the sub to move 4 mm then to reproduce 20 hz at the same level, 90 dB the sub must move 16 mm.

With that same example the sub at 20 hz must move 16mm X 2, 32 mm 20 times each second for a pure 20 hz tone. 32mm X 20 hz = 640mm/sec. At 40 hz it must move 4mm X 2 = 8 mm, 40 times per second. 40hz X 8mm = 320 mm/sec.

Just because a sub can move a certain distance to reach it's mechanical limit does not mean that it moves that distance every stroke. The distance it moves is what causes the pressure change in the car. The greater the displacement volume the greater the change in SPL. But yet there are other factors as well.

That's where I was getting hung up...so that makes sense. A 15 can produce lower frequencies because its excursion is greater which allows for fewer cycles per second while still maintaining a sufficient woofer speed to acheive sound. Is that essentially right? What limits the excursion of a smaller woofer? Manufacturing / Materials?

So theoretically a larger woofer has no drawback over a smaller one because it can reduce its excursion as required to reproduce higher frequencies just as clearly as a smaller woofer?

No, you are still confused. The fequency is determined by the musical note, drum tone, sound effect etc. If a sound that is reproduced requires the sub the move 20 cycles per second, aka 20 hertz then the sub must move in and out 20 times per second for the duration of that note. The size of the speaker makes no difference in that regard. The size of the speaker is relevent to how loudly it can reproduce that sound. A 15 inch woofer for example does not have to move as far to recreate the same sound at the same amplitude as a smaller woofer. Larger speakers in general can displace more air. It takes more air displacement to recreate lower frequencies at "realistic" levels.

Subwoofers are generally limited to frequencies below 80 Hz or evn below 70 Hz. Many SQ listeners would limit them to even a smaller bandwidth. Therefore it is unimportant how clearly they can play midbass or midrange frequencies because they should never need to reproduce those sounds. It would be like using a train to transport a ziplock bag full of feathers.

if subs are supposed to play from 80 and down, why does my jbl amps lpf go from 32-320hz?

Basically it means that the amp is capable of reproducing the midbass frequencies and the lower midrange. That is not a bad thing. And for people looking for the loudest stereo in the land it is a good feature.

[QUOTE=jmax]No, you are still confused. The fequency is determined by the musical note, drum tone, sound effect etc. If a sound that is reproduced requires the sub the move 20 cycles per second, aka 20 hertz then the sub must move in and out 20 times per second for the duration of that note.QUOTE]


I understand frequency and its relation to musical notes. I guess I don't understand why larger woofers can produce lower frequencies. For example, my 10" Type Rs are rated down to 28 Hz at a particular distortion, while the 12" goes down to 24 and the 15" down to 22. Is that not a function of woofer size, and more to do with something else?

There is more to it than the size of the woofer. And eight inch woofer rated down to 40 Hz will play at 20 Hz. But likely it would not be efficient enough to be useful in that range without a ported, bandpass, or some other more complex enclosure.

The motor, cone, suspension, frame and enclosure all play important roles. In a vehicle an 8 inch sub in a sealed enclosure can definitely be felt at 20 Hz.