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In Reply to: RE: Subs in the ceiling or under the floor PPSLIB posted by Scholl on February 20, 2012 at 12:33:35
Hmmm... maybe from the floor.
Yes, the AE seems like thoughtful people.
Why PPSLIB? I don't see a definitive design in my research. It looks like people are pointing drivers in every direction.
And it doesn't seem to matter what the size of cabinet is or the opening into the room.
Follow Ups:
Several reasons, push pull slot load cancels both secondary vibration and harmonic distortion. Although with IB the drivers arn't as closely coupled as in a boxed design so harmonic dostortion may not get canceled as much. There ia also some compresion because the slot has less area than both woofers together. This will increase air vilocity. Check out the link for a behind the wall project. Just copy it but point it down instead. It'll take two or four woofers.
Scott
Thanks. That's what I was looking for. It actually looks pretty easy (even for someone like me). I was thinking push pull was one cone pointing in and one out...but it looks like both pointing in is the way to go.
I hope you include a few pictures and your listening impressions.
Most of the listening comments I've read seem to be about the the impressive low frequencies and spl's (aka action movies). I'm not completely convinced that IB's are going to fit in seamlessly with the rest of my system (horns and 4 watt amps) .
Do you think IB's can deliver clean, tight and defined bass (between 20hz and 50hz). Are you going to filter out the lowest frequencies as I imagine it would wreak havoc with a turntable. I want to hear every note Ray Brown plucks....nothing mushy or it will drive me nuts (and I'll be stuck with holes in my carpet and floors).
Ok...time to contemplate placement, equalization and amplifying.
Greetings,
FWIW I use a mono 8 driver AE-IB15 Infinite baffle subwoofer system in my 2 channel audio-only set up. I run it from 50Hz and down. It goes down to 20Hz quite easily. More important that just the remarkable frequency response, is the sound quality. If you go to the "cult" I have a thread: "Legend3215 project". It's a few years old, so you'll have to go back several pages to find it. My driver mounting method did garner some negative attention though. In my very strong opinion, it's the end all, be -all, last word in subwoofing bass.
Here's an interesting discussion from a decidedly more 2 channel perspective:
http://www.goodsoundclub.com/Forums/ShowPost.aspx?PageIndex=7&postID=17220#17220
The quote, "be detached mechanically from the floor in order to avoid such "bone vibrations"" caught my attention.
I am thinking about supporting the IB box on the floor of my sub floor crawl space and then making some sort of bladder that seperates the ib box and the floor. Maybe out of rubber material used in auto dampening, like this:
http://www.secondskinaudio.com/vibration-mat/damplifier-pro.php
AE delivered two IB15-8 ohm woofers. They are now mounted in the manifold cone to magnet and wired in parellel but out of phase. There are two manifolds mounted close to the front wall bottom corners, behind the wall fireing into the room. The second manifold has two AE TD15S-4 ohm woofers (untill the other two IBs arive) again monted cone to magnet but wired in series but out of phase. A quick sweep shows both manifolds rolling off in the mid 20s with output down to 10hz. The 15S set measures 4-6db louder than the IBs.
Sonicly the setup is awsome. Bass is unwavering and powerfull.
While running loud, I mean very loud, the cones move less than a 1/4 inch. Fast air flow can be felt comming out of the manifold but the manifold has little vibration of it's own, same with the wall. The push-pull cancilation works very well. I wouldn't be afraid to tie these into the wall or ceiling. The manifold could be built to be lagged into the rafters fireing down into the room.
For woofers I would consider any one with Qt above .4 and an Fs below 25hz and large Vas, long Xmax. I think the most important parameter is the Fs as low as possible. Qts and Vas are secondary considerations factoring in room gain and EQ as long as Xmax and power are available to take the EQ. A woofer with large Vas will be more efficient and easier to drive at low power. The Dayton Titanc seems a great choice wired in series to save the amp some strain or one channel per woofer if the budget permits. One pair should be good for most people, two pairs even out the room response some. Parts Express has several 15s that'll work just fine some costing below $100.00. 4 Titanics with one or two of their 1000Watt plate amps wire in a seres\parrellel for 4 ohms(one amp) or 8 ohms (two amps)total in a room would destroy the place!!
On a side note: My manifolds use 2.5 to one conpresion so the slot is only 8" wide. The high frequencies drop above 200hz. This small of a slot wouldn't work well above 100hz I plan on crossing at 70hz where a natural room dip occures.
Scholll.. thanks for the info.
A couple of questions:
Are you saying that cheaper drivers (as long as they have the appropriate specs) will sound just as good as the more expensive woofers? Same question but insert amps. I didn't see any $100 subs at Dayton... the cheapest were $250. The Acoustic Elegance IB15 seem like the top of the class in IB woofers although I don't want to spend anymore than I have to, but... if they sound the best then I'm in.
I also plan on crossing over somewhere sub 70hz. The clearance between floor joist are a hair under 15". Is that too much space? or should I not worry about that and just build the box and opening according to the space that I have? By the way- what exactly is the manifold? Is that the opening?
I was going to place a couple of subs I have on their backs and move them around the room to experiment with placement. The best place from a practical perspective are just in front of the speakers. Any thoughts or advice with placement?
Of all the things I've read, nobody talks about time alignment. I'm thinking that placing them as close as possible to my speakers will address this issue but may not be the best solution for addressing room modes. I'm also thinking that if I put them near the speakers that I may be able to cross them over at higher point which may help with directional issues as you go higher in the registers. I don't want to insert another xover in my system at this point so (for now anyway) I will just be coming in under my current bass which rolls off around 40hz.
Experimenting will be the final judge... but I won't be cutting too many holes in my floor, so just thinking out loud about possibilities.
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