New IB sub question

[Tiny]

well now that sister-in-laws new speaker project is well underway I started putzing around with the notion of building a new sub for me. In the wall between my living room (a big open l shaped space that also goes into my dining room ) and the garage I have mounted an old air conditioner about 5ft off the ground. The as* end of it hangs into my garage and so long as I put it back when i move I can't see moving as any big deal as far as the landlord is concerned. I also have central air so removing it will not be an issue six or seven months from now. Would 5ft off the ground be too high for an IB sub. In theory 8" double woofer speakers produce as much low end as a single twelve and do it better with less power, is less still more when it comes to IB subs?. To go along with my 1k watt plate amp I just managed to pick up a dozen 8" 1200 watt Pyle 2 ohm subs. Any thoughts on turning those and my garage into an IB Sub?

[Otto]

I think you can do it! There should be no problem having an IB sub 5' off the floor of the room. Many people have them in ceilings and walls. It sounds like you are limited in the exact placement, and that's OK. Since you will be taking the drivers and amp with you, you have nothing to lose.

Good luck!

[Mike P.]

How successful it will be will depend on the specs of the subs. What are the T/S parameters? How do you plan on wiring 12 - 2ohm subs to a 4 ohm plate amp?

[toecheese]

The location and amps sound fine, but multiple small drivers are problematic.

The first is that to move serious air, you'd have to have a lot of them. Having a lot of them means a complex manifold, which means you start introducing phase cancellation delays and distort the sound- which is the antithesis of IB.

The second is that since IB are free air, you need high-excursion drivers, and it would be unlikely that you can find such a creature in 8" packaging.

[Tiny]

Mike P. wrote:

How successful it will be will depend on the specs of the subs. What are the T/S parameters? How do you plan on wiring 12 - 2ohm subs to a 4 ohm plate amp?

I don't have all of the specifics on the speakers yet, I haven't yanked the box or speakers out of the car they came in. These are all fine working polycone speakers, and it my wife wouldn't kill them the first time she needed to throw **** in the back of the CRX I would leave them in place. I drove it home and don't think I have ever heard Blue Oyster Cult or Zeppelin sound better than it did in this little car (grand total of 22 speakers that I can see, I think there may be more under the front seats I can't quite see). The wife however has enough problems driving as it is without blasting hair band ballads through that many speakers.

They are currently wired to a 2ohm 1200 car amp, I figure I will split the current wiring setup into 2 series which should make it 4 ohm, though there are several ways I could get 4 ohms by mixing series and parallel setups.

[Tiny]

toecheese wrote:

The location and amps sound fine, but multiple small drivers are problematic.

The first is that to move serious air, you'd have to have a lot of them. Having a lot of them means a complex manifold, which means you start introducing phase cancellation delays and distort the sound- which is the antithesis of IB.

The second is that since IB are free air, you need high-excursion drivers, and it would be unlikely that you can find such a creature in 8" packaging.

Lets say I go ahead and play this by trial and error, the worst thing that happens is I waste several hours that were already free and at most a couple of sheets of free plywood. I hauled it for a guy who then thought I should unload, carry it two hundred feet to where he wanted it (across the yard he wouldn't let me drive over), then sticker stack it neatly for him too. After three years of it sitting in my storage area still on the trailer I don't think he wants it anymore.

Now assuming I do this the question is how big to make the manifold The hole coming into the living room is 15"x24" and I have 9ft floor to ceiling in the garage. What would be the best position to mount the subs? I am an IB noob, I have never heard a home installed one, much less built one before.

[Otto]

Yeah, right back where I started. You have the drivers, amp and wood. Try it.

Make the manifold as big as your opening. I'd probably use eight 8" drivers, mounting two of them on each "wall" of the manifold, all facing in.

Yeah, this is an experiment.

Good luck!

[Mike P.]

I know that the recommended manifold opening should equal the area of the woofers you are using. The average 8 inch sub has 32 square inches of surface area. 12 subs would be 384 sq. in. Your 15 x 24 opening is 360 sq. in. That should be close enough. Do you know what the model number is of the Pyle subs?

[toecheese]

The best position? Create a spherical shell out of ply, with all the drivers facing inwards and attached to that opening.

I would send you to the 'cult' site, but you'd be told not to bother with what you're doing.

[Tiny]

Mike P. wrote:

I know that the recommended manifold opening should equal the area of the woofers you are using. The average 8 inch sub has 32 square inches of surface area. 12 subs would be 384 sq. in. Your 15 x 24 opening is 360 sq. in. That should be close enough. Do you know what the model number is of the Pyle subs?

I went and took one of the speakers out of the box and it isn't quite what the listed specs in the auction sales sheet said but I can live with that the car was only $500 and I didn't buy it for a banger built sound system.

Incidentally the subs are not 1200 watt rated they are 800 watt and 4 ohms. Model number PLBW84.

Please excuse me for a while, I am gonna go fire up Zeppelin 2 and enjoy the stereo while it is still in the car.

[Mike P.]

There are no T/S parameters available for the PLBW84 on the Pyle website, but they are dual 4 ohm subs.

[Owen Bartley]

Tiny, give it a shot. If you can manage to fit and support the manifold and it isn't in your way, I don't see why you shouldn't give it a go. You may end up better off just building a more conventional box or two, but hey, where's the fun in that? I say go for it, and make sure you take lots of pics!

[kesa32]

l think you'll be wasting your time and money ( because the manifold would have to be replaced later by another to accomodate larger better drivers ) .......the first serious transiet will destroy these drivers, you'd be better off selling them/using them elsewhere rather than destroying them (unless it is for music only usage )........sorry, not trying to dampen your keeness on ib's but really you need to know the specs of the drivers and go from there otherwise you'll end up with a flawed result not true to what an optimal ib is supposed to sound like....try asking here....http://ibsubwoofers.proboards51.com/index.cgi

cheers ken