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Decided to pursue dipole subs...

post #1 of 9
Thread Starter 
I'm halfway through a learning/experimentation stage regarding subwoofers. Not too long ago I was proud of myself for rewiring my old subs directly to a Crown XTi-1000 and creating my own parametric EQ curves. Then I started swapping out drivers and my world changed for the better. AT that point, maybe a month ago, I came back to AVS looking for ideas. So many incredible projects on this site, I'm blown away.

Since I live in downtown Philly, I do not have the space to build a dedicated home theater. Anybody who's seen a Philly rowhouse knows, space is limited compared to a modern suburban home. So, IB is not an option and LLT, as appealing as it sounds, would burst my room at the seams, because I'm already hosting a pain of dual 15" mains with huge horns.

For the last month I've been messing with smaller tuned boxes as well as sealed subs. Nothing among those options made me truly happy, and then I decided on a whim to try out a dipole sub. I knocked the rear wall out of a small sub enclosure and put it front and center in my system, about 1/3 the distance from the speakers to the listener, precisely centered.... and it turns out that's the sound I've been looking for. KISS at work. Today the back comes off my larger box which contains the Polk MOMO 15". It should blow away the test sub from last night -a 10" polk driver taken from a PSW-125 and put into a .box from a $99 Sony sub.... and yet those junk parts managed to sound so good... so damned good I'm ready to commit to this approach. The little 10" dug deeper and was more on-time and any ported or sealed sub I've messed with, limited only by its diminutive size and inability to play LFE effects from blu-ray without bottoming out - time for much, much more displacement. I need the best possible impulse response for mastering my tracks, and I can deal with monitoring at moderate volumes... if the reproduction is faithful and full-range. Dipole did all that.

I'll see what I can do about pictures and graphs. This isn't the 'real' sub I'm envisioning ending up with, just an experimental staring point. I think the key here was deciding what kind of bass sound I like. I can't get enough of that box-less sound, it's appeal to me was immediate and obvious. I'm curious how the MOMO will do in this application. It voids the warranty to use it IB style, but it really seems well-suited to the application. Gotta run and get some carbide blades and cut my box open now...
post #2 of 9
You will find many like-minded folks here:

http://www.audiocircle.com/index.php?PHPSESSID=tcf62urhclmiqaon86c67l8fc35tm7gi&board=16.0

Open baffle servo subs might be just what you are looking for

http://gr-research.com/sw-12-16fr.aspx
post #3 of 9
cool.

they rolloff faster than sealed, so don't expect as much spl and you will probably need eq.

if you are not familiar with linkwitz, check his site out:www.linkwitzlab.com. he has lots of information on dipoles.
post #4 of 9
Thread Starter 
Yeah I spent 8 hours reading Linkwitz stuff yesterday. I like the result a lot, but actually I find the smaller driver to be more satisfying in this application, despite the extreme limits on SPL, the small-driver tightness makes the deep bass very very visceral. I could see a dozen 10" drivers being the foundation of something real sweet. I sealed my 15" back up, the MoMo probably is ill-suited for this duty, just like Polk said. I put the MoMo into a sligtly larger, sealed, down-firing box which seems to suit it best. Time to mess with some more drivers in the dipole boxes.
Quote:
Originally Posted by LTD02 View Post

cool.
they rolloff faster than sealed, so don't expect as much spl and you will probably need eq.
if you are not familiar with linkwitz, check his site out:www.linkwitzlab.com. he has lots of information on dipoles.
post #5 of 9
Thread Starter 
OK so here I go jumping down the rabbit hole. I'm convinced what I need is one infrasonic sub, a corner-loaded sealed 15" or 18" in a medium-large box, and one near-field dipole with a 10" driver that skips anything below 28hz. I'm listening to exactly that right now and I'd definitely say it sounds' 'integrated', I absolutely love the immediacy of near-field dipole bass, but it's so nice to have the huge rumbles as well. So, that's the goal, two (or three or four) subs. One or more big ones to create the rumble, and a 10" or 12" dipole to create the subtlety and slam.
post #6 of 9
If you are interested in maintaining quantity and extension with dipole bass, the fi car audio brand IB3 subs, particularly the 18", work great and move lots of air for little money.

More up close with less extension and output but extreme quality for the price, the aespeakers dipole 12" and 15" series are tough to beat.
post #7 of 9
Thread Starter 
I'm definitely going to be experimenting with dipole bass, so at some point getting dedicated drivers will be a good idea. In the meantime, here's my ghetto Velo 1812. The Sony box on top used to hold an 8, I jammed a Polk 10" driver in there and knocked the back wall out of the box. Instant cheap dipole. Underneath is the Polk MoMo 15", now firing down onto a slab of 18" paver stone from Lowes. Yes, the sub is being held by cans of dog food. Three 18" paver stones form the 120 lb. 'lid' of the bottom sub. Duct putty (plasticine) is used throughout seal the sub and also to separate each stone with an anti-resonant layer and finally to adhere the dipole to the sealed unit.

Each sub gets one channel from my Crown XTi-1000, using EQ and Crossover to isolate each sub to its respective slice of the audio spectrum.

I decided it was best to have the sealed unit fire down in the hopes it would interfere less with the forward facing dipole. I've been running some tests in REW things are looking great, I'll have some graphs later or tomorrow.

Please don't laugh, this is all experimental prototyping and it sounds really good.





Quote:
Originally Posted by Bigus View Post

If you are interested in maintaining quantity and extension with dipole bass, the fi car audio brand IB3 subs, particularly the 18", work great and move lots of air for little money.
More up close with less extension and output but extreme quality for the price, the aespeakers dipole 12" and 15" series are tough to beat.

Edited by imagic - 8/14/12 at 3:26pm
post #8 of 9
imagic
I am laughing my a$$ off because if you live in downtown philly you are pi$$in all your neighbors off big time. If you are in a row then you are also rockin your neighbors houses!
Good luck with that. Seems to be a pretty agressive approach to getting down very low. But, I understand completely.
biggrin.gif
post #9 of 9
Thread Starter 
At least my rowhouse is on a corner, plus I simply don't make eye contact with 'that' neighbor. At least I'm not following through with building a LLT which I considered for a microsecond. The truth is that I'm finding stone enclosures to be the most intriguing thing, I'm messing with dipole and sealed, both made of stone (1.75 inch thick). Still weeks away from affording a new, 'final' build and anything still goes, but I definitely experienced some incredibly clean sound coming from a dipole but also from a sealed stone enclosure.

Of course I nicknamed this prototype 'Rocky 3" = 3 cubic foot rock enclosure sub.
Quote:
Originally Posted by Bone215 View Post

imagic
I am laughing my a$$ off because if you live in downtown philly you are pi$$in all your neighbors off big time. If you are in a row then you are also rockin your neighbors houses!
Good luck with that. Seems to be a pretty agressive approach to getting down very low. But, I understand completely.
biggrin.gif
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