HELP--What sub design would work best for this?

I kinda have my heart set on a subwoofer cabinet design to sit under my trunctuated pyramid satellites. Something VERY similar to the Wilson Puppy sub. I want to use 2 Vifa P21 8" woofers in an enclosure that is 36" high, 10 1/2" wide and 15" deep to match the footprint of the sat.

The satellite is transmission line so that was my initial thought for the sub but I don't know if 2 drivers in that small of an enclosure would be beneficial or actually hurt things. Or, like the puppy, I could use a rear port and use some internal bracing. Or, I could just go sealed.

If my goal is quality over ultimate extension or loudness capability, what design would be best for 2 8" woofers in that enclosure? Also, I want to use a plate amp to drive the 2 Vifa's mounted to the back of the sub. Would a single PE 240 watt plate amp drive the 2 P-21's?

Any thoughts on this project would be great!!
 
First question is do you want subwoofers or bi-amped woofers. It sounds like you really want the 2nd, and that is a fairly different approach. The latter would have more focus on crossing over higher, possibly as high as 200-300 Hz. The benefit here is actually what it does for the midrange and the dynamics of the system.

TL - just too big for what you have in mind.

It's more about ported or sealed. If you go sealed then displacement is more important. You can use a Linkwitz transform to get in a bit more depth at the cost of output.

First driver that comes to mind is the Peerless 8" HDS - quite decent xmax and has a low distortion motor, very good value for money and low distortion for its price point.

Another that comes to mind is the Adire Extremis, actually smaller than you had in mind but with 4 of them in vented boxes, you would have woofers with the kind of displacement you'd get from a sub!

Adire Koda 8" also worth considering. You may even find that one per side is sufficient. It combines the benefits of a subwoofer driver and a woofer - high excursion with the ability to cross higher than a typical sub driver.

I find the sound of Scan Speak midbass drivers to be very solid and appealing, you might consider them if your budget can stretch that far.
 
Thanks for the replies! I am looking to go to 27Hz or below with the subs. After a little research, I am finding that the 8" drivers I want to use may not get me there in a sealed system. 1 0r 2 per side....

What I could do is mount the driver on the side of the enclosure which would allow a single 12" driver that could do a better job.

Or, as these are pyramid sat cabinets, I could continue the subs in the pyramid shape which would allow for a 12" driver front mounted in the middle.

I'm on a "budget" somewhat, so I was looking to spend about $100 per side on drivers and $120 per side on the plate amps.

If I continued the subs in the pyramid shape, the final cabinet measurements would be 10 1/2" wide at the top, 21" wide at the bottom and 15" deep. What is the internal volume of that and what 12" driver at $100 would work best then to get me to 27Hz or lower sealed?

Thanks!!
 
I ask my question again, as it's critical to making your decision - do you want a sub or biamped woofers?

A sub will cross at 120 Hz at the highest and can be side mounted. Biamped woofers will cross higher and hence must be on the front.

Subs get you more extension and output, biamped woofers will do more to improve the midrange and dynamics of the rest of the system.

Atlas 12" subs are now selling for $100 if you get in quick if you want the sub option.

A single woofer of the largest size you can fit on the front is probably the way to go if you don't want a true subwoofer, but want to cross higher than 120 Hz.

With the extended pyramid size, what size volume does that involve?

Peerless CSX 10" is a great value for money woofer to consider. You could go with a pair of them perhaps per side sealed.
 
Thanks Paul. Looking for a sub versus woofers, but I want them to be "fast". The sats are good to 55Hz so I will cross them at 100Hz. I was told my enclosure was 3.1 liters.

I have been taught that subs larger then 10" are "slow" for music. Maybe I was taught wrong. That is why I was thinking two 10" drivers per side, like the Peerless 10" 850146 you mention as opposed to some 12" or 15" monster single sub.

What type of F10 would I expect to get in a 3 litre enclosure with 2 per side with those Peerless?
 
First off, your enclosure size of 36" X 10.5" X 15" would yield around 65 liters of volume or about 2.3 cuft. assuming .75" walls with some bracing.

Secondly, one 10" CSX Peerless in this enclosure would give an f10 of around 20Hz in either a sealed or ported alignment from what I have modeled. The ported alignment would give you a lower f3, the sealed would have a shallower roll-off in the low end. I would go for the sealed alignment myself.

You could go for two of these sealed in each enclosure for an f10 of around 26Hz. This would probably be overkill unless you are doing it just for looks, in which I would say go for it.

Thirdly, if you are going to power just one 10" per side then I would go with the 100 watt amp for each or split one 240 watt amp between the two. If you want to go the overkill route with two 10's per side then I would go with one 240 watt amp per enclosure.

Hope this helps,
Robert
 
Thanks Rob. Man, everyone is calculating the volume differently on this thing. I flunked geometry!!!!! Are you taking into account this is a pyramid?

Again, its:
10.5" wide at top
21" wide at bottom
15" deep
32" high

Yes, bracing will be used as well as there will be a plate amp and the driver in each enclosure. It will be 3/4" MDF.

You lost me on how 2 Peerless raise the F10 to 26Hz. 2 woofers are going to hurt the low end as opposed to 1?

You are correct on the "looks" part. 2 drivers in a 32" high enclosure would look better and is kinda what I wanted to do from the outset. Of course if it's going to hurt the low end extension, I would go with just one.

On another "looks" note, I wanted to use one amp per cabinet regardless because I don't want to have a "sub amp box" somewhere in the room with wires running in and out everywhere. Do you guys think that 240 is overkill for 2 Peerless then per side?



Thanks!
 
I have been taught that subs larger then 10" are "slow" for music. Maybe I was taught wrong. That is why I was thinking two 10" drivers per side, like the Peerless 10" 850146 you mention as opposed to some 12" or 15" monster single sub.

No offense intended, but yes, you were taught wrong. Provided you cross low enough and steep enough, a big woofer is no 'slower' than a small woofer. 'Fast' bass is a misnomer. You certainly can get great bass using multiple 8" drivers, its jut not the most efficient way of getting there.

That said, the peerless drivers you are looking at are very good, and if you are still set on the idea of 8" drivers, have a look at their 8" XLS drivers, as well the Dayton RS 8" or 10" driver.
 
I'm really hoping to go with 2 Peerless CSX 10" ers per side. With an Fs of 22.6 and Qts of .35, for $63 it looks like a steal. Plus, if I buy 4 I get the quantity discount of $60 each.

I just want to make sure that 2 will keep the F10 of the enclosure as low as 1 would and not "hurt" things. I also want to make sure of the internal volume. 3 people have told me 3 different values now!
 
I was going off your original dimensions for the sub enclosure in post #1. With the added volume of the pyramid enclosure the f10 of the dual peerless 10's would drop to that of the single 10". The reason the f10 raised for the two 10's in a single enclosure was that 65 liters was smaller than optimal for the two drivers. Again, the truncated pyramid enclosure would give you enough volume for better low-end extention when using two 10's.

One 240 watt amp per enclosure with two 10's would be good.

I know you wanted the two subs per enclosure but just to offer another route Vifa makes a nice 10" sub (MA26 at Madisound) and I hear the Dayton 10" Reference Series sub (not the exsisting woofer) is coming out soon. Both are around $120 per sub and would work well in a sealed box of your size. The Vifa looks pretty cool with an aluminum cone and fiberglass dust cap.
 
The Vifa's f3 would be around 25Hz with an f10 around 15Hz so it will go deeper than the peerless setup. However, with the peerlesses you will have more output potential since you would be using four of them. If you went with the Vifa's I would build the straight-sided enclosure because they don't need the extra volume of the pyramid and it would be much easier to construct. For reference I came up with 100~120 liters for the volume of the pyramid depending on the method of construction.

The enclosure modeling program I use can be found at http://www.pvconsultants.com/audio/eq/boxcircuit.htm It's free and runs off Excel so nothing too difficult. I recomend downloading it and playing with different combinations of drivers and enclosures to see how things can compare. It's pretty fun.
 
Thanks again Rob. I truly appreciate your help on this. Those Vifa numbers are really impressive for a single sealed woofer sub. Again, I'm a DIY novice so I couldn't tell you a Vas from a Qts (well, I could tell you that one, but not much more!), coupled with the fact that I have too few patience to learn it. Thanks for running the numbers for me!

Your right, keeping it "straight" would be much easier to build. So it comes down to pyramid-peerless, straight-vifa. I will decide from there.