What is the best type of subwoofer?

JohnR · « **Reply #20 on:** 24 Jul 2012, 06:29 pm »

Quote from: WireNut on 24 Jul 2012, 05:36 pm

2.5 L push/pull compound vented cab (that's 1/2 the size of a sealed box) = -3db at 27.5 Hz

That sounds like an isobaric.

WireNut · « **Reply #21 on:** 24 Jul 2012, 07:14 pm »

JohnR.
It is an Isobaric. The only way I can come up with anything even close to the specs of the 2.8cf push/pull box is to build a huge 11.5cf vented box. The HUGE vented box would have a 6db increase in SPL with 100 watt input over the PP box.
Another advantage of the PP box is because the drivers are mounted one behind the other, that
will drop my tweeter down from 46" to 34" due to the shorter PP cab I can build. That puts my tweeter closer to ear level where it should be.
I have been looking for a new cab design for my W12's.
Looks like this project is a GO for me.

Thanks for getting me fired up.
Now, I just have to read up on designing/building a correct PP box.

Steve.

rajacat · « **Reply #22 on:** 24 Jul 2012, 07:17 pm »

I'm surprised no one has mentioned these servo subs. available in kit or complete.

They've received almost universal acclaim. I suppose that if you're just looking high SPL for HT with SQ of secondary importance, they might not be the best choice but for music lovers they'd be my first choice.
http://www.rythmikaudio.com/

JohnR · « **Reply #23 on:** 25 Jul 2012, 07:09 am »

Quote from: WireNut on 24 Jul 2012, 07:14 pm

It is an Isobaric.

Hi Steve, no complaints from me as my (sealed) subs are isobaric. That isn't what I meant by "push pull" but no worries

JLM · « **Reply #24 on:** 25 Jul 2012, 10:03 am »

Unless you have an infinitely long room, the research by Toole et al, shows standing waves from a single or stereo subs will produce +/- 20 dB frequency responses. This is something that tons of treatment might solve or EQ can solve but only at a single location.

So the best type of sub is two subs located at opposite ends of the room. I just found this "secondary sub" that has a mike and circuitry to sense this effect and produce out of phase cancellation to eliminate the +/-:

http://www.spatialcomputer.com/page9/page10/page10.html

daz_bike · « **Reply #25 on:** 25 Jul 2012, 07:21 pm »

JLM that is interesting. I would prefer not to go down the route of bass traps galore. I have two subs and would like to try this. So believe what you are saying is locate 1 sub in the front of the room (normal location) and 1 sub at the back of the room which will . Is the idea to run the sub at the back of the room with the same signal as the sub at the front of the room but out of phase?

*Scotty* · « **Reply #26 on:** 25 Jul 2012, 09:12 pm »

You've got it in one. Locate it in the center of the rear wall and run it out of phase, ideally you would like to be closer to main speakers and front sub than you are to the rear sub. This gives you time to hear the bass wave. Before it is canceled out by the output from the rear sub. The crossover frequencies should be matched front to rear. If you have to sit closer to the rear sub than the front sub then you will need to add delay to the rear sub so that it cancels the front wave before it hits the rear wall but after you have had a time to hear it.
The Behringer DCX 2496 will allow you to dial in the right amount delay.
Scotty

WireNut · « **Reply #27 on:** 2 Aug 2012, 05:59 am »

Isobaric is a very good design IMO.

medium jim · « **Reply #28 on:** 16 Aug 2012, 10:56 pm »

What about multi-speaker subs such as Vandersteen....

Jim

ratso · « **Reply #29 on:** 16 Aug 2012, 11:38 pm »

i read a lot of forums in HT as well as 2 channel circles, and the HT guys are way ahead of the 2 channel guys when it comes to subs (and yes i'm talking about for music as well as HT use, it used to be 2 channel mags like stereophile recommended little tiny wuss subs for music because they were "faster"

now they see the light with reviews of JL's gotham et al). if i had my dream sub setup it would be 2 subs from funk audio in canada. no wait, 4 subs from funk audio. add in some top notch room correction and crossovers so you can vary the slope and you're set. here, drool:

http://www.funkaudio.ca/18.0.html

asull2k · « **Reply #30 on:** 17 Aug 2012, 12:22 am »

http://www.rotarywoofer.com/

oboaudio · « **Reply #31 on:** 18 Aug 2012, 12:34 pm »

Below 25 hz the Rotary subwoofer is awesome. I have owned this subwoofer
for 4 years and there is no going back to conventional subs. The rotary
subwoofer can handle anything (Saturn rocket launch is the best example and
will destroy most conventional subwoofers.) Transients reproduced by
this sub are frightening.

Bob in St. Louis · « **Reply #32 on:** 18 Aug 2012, 01:59 pm »

Is yours a DIY, or a Thigpen?

SteveFord · « **Reply #33 on:** 18 Aug 2012, 02:40 pm »

I believe he answered that one as an Emminent Technologies rotary subwoofer in the Planar Circle a long time ago?
I now know how Jenny will meet her demise - death by subwoofer.

rbbert · « **Reply #34 on:** 18 Aug 2012, 08:36 pm »

Quote from: *Scotty* on 25 Jul 2012, 09:12 pm

You've got it in one. Locate it in the center of the rear wall and run it out of phase, ideally you would like to be closer to main speakers and front sub than you are to the rear sub. This gives you time to hear the bass wave. Before it is canceled out by the output from the rear sub. The crossover frequencies should be matched front to rear. If you have to sit closer to the rear sub than the front sub then you will need to add delay to the rear sub so that it cancels the front wave before it hits the rear wall but after you have had a time to hear it.
The Behringer DCX 2496 will allow you to dial in the right amount delay.
Scotty

I'm pretty sure the optimal placement for 2 subs is catty-corner, with a reasonable alternative midway on the sidewalls both facing into the room (i.e., each other). When you get to three or more, the optimal placement usually includes one in the middle of the front wall at the ceiling. Analyses of these and other placements have been published (I think in Widescreen Review, but I'm not sure).

bakufu · « **Reply #35 on:** 18 Aug 2012, 08:52 pm »

at one point i actually considered installation of a thigpen rotary subwoofer. the idea is both wacky and compelling -- turning your whole house into a giant bass-generator. unfortunately, my property adjoins a nature preserve, and i thought i might run afoul of some local environmental ordinance, the finale of the mahler second blasting red-tailed hawks out of the air.

i finally opted for a pair of 18.3's from nathan funk. they've yet to arrive, but oh forbin are they beautiful.

medium jim · « **Reply #36 on:** 18 Aug 2012, 09:23 pm »

Talk about a wall of bass, or in the immortal words of Robin "Wholly Bass Batman".

Jim

bakufu · « **Reply #37 on:** 18 Aug 2012, 09:54 pm »

i'd like to know whether rotary sub users experience an unusually low incidence of kidney-stones.

*Scotty* · « **Reply #38 on:** 18 Aug 2012, 11:37 pm »

rbbert, you might find this information useful.
http://vbn.aau.dk/files/12831869/AC-phd.pdf.
Scotty

rbbert · « **Reply #39 on:** 19 Aug 2012, 02:26 am »

http://www.madronadigital.com/Library/BassOptimization.html

Somewhat similar, although it does include the three sub configuration with the ceiling sub as optimal.