[JDUBS]

Guys, has anyone ever tried one of these?  I can't put up traditional traps....but this thing looks like an interesting (potential?) alternative:

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

-Jim

[JDUBS]

Here's the ad on Audiogon:

http://app.audiogon.com/listings/463015

[Rclark]

Huh.. I'd be interested in seeing a small room model... And some reviews. I wonder if this will allow apartment dwellers to pump up the jam, placed one front corner one rear corner.

[JDUBS]

Huh.. I'd be interested in seeing a small room model... And some reviews. I wonder if this will allow apartment dwellers to pump up the jam, placed one front corner one rear corner.

Exactly what I was thinking.  I'm in an apartment and this COULD be very interesting.  The only real review / discussion I found was on head-fi:

http://www.head-fi.org/t/583355/spatial-computer-black-hole-anti-wave-generator

Which seems very positive. 

-Jim

[bpape]

Bag End offers something similar.  The BE has 2 different frequencies with contour and other controls which can be operated individually or together.

For very very low frequencies which are difficult to address with treatments or in situations where treatments cannot be used, it can be a nice solution.  Just understand that they're designed to deal with 1-2 specific problem frequencies and are not broadband bass solutions.

Bryan

[JDUBS]

Bag End offers something similar.  The BE has 2 different frequencies with contour and other controls which can be operated individually or together.

For very very low frequencies which are difficult to address with treatments or in situations where treatments cannot be used, it can be a nice solution.  Just understand that they're designed to deal with 1-2 specific problem frequencies and are not broadband bass solutions.

Bryan

Bryan, is the Bag End solution still around?  The Spatial solution looks pretty cool in that it seems very "easy".  Just stick it in a corner and plug it in.  It has a mic and dsp on-board.  I think the only thing to really adjust is volume.

The FR plot on the Spatial site shows one Black Hole dealing with several bass peaks and dips.

-Jim

[ratso]

i started a thread about this when it came out somewhere (probably here) and of course, no one knew anything about it as it was brand new. but someone sent in a link that nelson pass had come out with something that was basically the same theory in the 80's i believe. there was a discussion with nelson talking about it, saying that yes, it works, but not enough people were interested so it was eventually dropped. **edit** here it is
http://www.stereophile.com/roomtreatments/1289phantom/index.html

BTW: off the subject, but i checked that head-fi link above. this has to be about the tenth thread i've read over the years over there where someone writes in what obviously is meant to be a helpful opinion on something and everyone jumps on them as being some kind of "corporate shill" because they are not in their little head-fi click. good god.

[JDUBS]

i started a thread about this when it came out somewhere (probably here) and of course, no one knew anything about it as it was brand new. but someone sent in a link that nelson pass had come out with something that was basically the same theory in the 80's i believe. there was a discussion with nelson talking about it, saying that yes, it works, but not enough people were interested so it was eventually dropped.

BTW: off the subject, but i checked that head-fi link above. this has to be about the tenth thread i've read over the years over there where someone writes in what obviously is meant to be a helpful opinion on something and everyone jumps on them as being some kind of "corporate shill" because they are not in their little head-fi click. good god.

Ha!  Yeah, the head-fi stuff....I tried to look beyond that.  Pretty annoying, though.

Yes, the Nelson Pass "endorsement" for the technology is a great thing and gives me more confidence in this as a good solution.

-Jim

[ratso]

http://www.diyaudio.com/forums/pass-labs/12121-active-absorbers.html

here, i think he gives plans to build yer own in this one.

[Ethan Winer]

For very very low frequencies which are difficult to address with treatments or in situations where treatments cannot be used, it can be a nice solution.

Yes, but with a few caveats. One is that an active trap must be able to keep up with the output of your main speakers and subwoofer. If those play louder than an active trap can counter, the trap will no longer function and will add distortion into the room. I'm also skeptical about the "positional" improvement of active traps, though I admit I've never tested this. Conventional bass traps improve the response and ringing everywhere in the room. Bass waves travel all over a room, so you cover a fair amount of surface with traps. But an active trap is the size of a speaker cone. So even if it absorbed 100 percent, it's too small to do much. To solve this the trap must be set to absorb more than 100 percent - much more. I suspect that then makes the improvement positional and, like EQ, makes things worse in some parts of the room.

If anyone has an active bass trap and is within driving distance of me in Western Connecticut, I'd love to visit you in person with room testing software.

--Ethan

[bpape]

Yes - it has to be able to keep up to fully compensate. That said, one can set the level lower to avoid distortion (at least on the Bag End) to maybe not fully address but simply make the problem less intense.

Not sure what you're talking about with the cone area.  The cone area of the monitors producing the problem likely aren't that big or not much bigger.  The anti-wave would spread through the space just like the direct wave would - though I agree that it would be best most likely for purely axial issues. Just guessing on this as I've never fully tested one.

Bryan

[Ethan Winer]

Not sure what you're talking about with the cone area.

Let's say you have a bass trap that absorbs 100 percent at some very low problem frequency like 35 Hz, but it's only one foot by one foot in size. We both know that won't do much in a room simply because it's too small. Likewise, an open window one square foot also has perfect absorption, but such a small opening can't "absorb" enough to do much. So in order to simulate the much larger treated surface area required, an active bass trap must absorb more than 100 percent. I believe that then makes the improvement positional, affecting the response and ringing most where the input microphone is placed, and less elsewhere in the room. And like EQ, I suspect the response will actually be made worse at other locations. Versus passive traps that always make things better everywhere. Again, I haven't had the opportunity to test this, but I don't see how it could work any other way.

--Ethan

[bpape]

Agreed on the square footage on the window and panel. No argument there at all.  But those are passive devices that can only impact what hits them. An active device generates a spherical wavefront that also spreads throughout the room - just like the initial wave created by the system speakers.

Like I said, it may be somewhat position dependent certainly as if you're sitting in a place with say a 70hz null off the rear wall, you'd tune the active to hopefully help that. Now if you moved and the null now existed at 60Hz, the 70Hz 'tuning' of the active device would need to be changed accordingly.

Bryan

[JDUBS]

Guys, I shot Clayton at Spatial an email trying to get more information on the product and will relay what I hear from him, here.

-Jim

[Rclark]

 Thank you I totally appreciate that, and am interested in comments by others who are not involved in basstrap production. 

[spiritofmusic]

Hi everyone, first post on Audiocircle, here goes! I have had the Black Hole installed at home for the last week or so. It's a (just over) 1 cubic foot subwoofer style box with built in dsp/amp and 3 drivers front/l/r. It's placed behind me, along rear wall, corners are recommended. Operation is automatic with built in mic and minimal user controls. I listen thru Zu Definitions which pump out a LOT of bass, in a large loft space to one half of a 27'wide x 22'deep x 13'high area, and have a bass node at 27.1hz, and it's designed to "remove the rear wall" by eliminating standing waves/bass nodes, and so eliminate the need for bass traps/diffusors etc
Ok, impressions are of reduction in bass hash and opening up of soundstage, this seems to be improving everyday. The effect is subtle, but v.effective, and soundstage definitely contracts when unit is switched off. My girlfriend who is decidedly non audiophile and listens to an 80's Akai midi system(!), but has the sharpest hearing of anyone I know, immediately picked up on lower noise floor, increased detail retrieval and greater ease to sound.
The better news is that smaller rooms will have greater bass integration issues than mine, so the unit will have an even greater effect in those rooms.
All in all the most intriguing upgrade I've made in a while, on a par with converting to balanced power to system and removing conditioner/filters etc.
Clayton Shaw at Spatialcomputer answered all emails promptly, which aided my decision to purchase, but do ask him to double box unit, mine was nearly damaged in transit to the UK.
Regards to all, Marc.

[Ethan Winer]

An active device generates a spherical wavefront that also spreads throughout the room - just like the initial wave created by the system speakers.

Well, as we know, bass waves don't spread out evenly in a room from any loudspeaker source. So for an active trap to work, I think it's radiation peaks need to more or less align with the peak locations from the main speaker.

To Rclark: I too would love to hear from the manufacturer of an active trap. In particular, I'd like to see waterfalls of several locations around the room, to see if the improvement is positional or not. This is a key piece of data that I've never seen presented. Also, usually (but not always), those of us in the business are the most knowledgeable about how these products work.

--Ethan

[JohnR]

Agreed on the square footage on the window and panel. No argument there at all.  But those are passive devices that can only impact what hits them. An active device generates a spherical wavefront that also spreads throughout the room - just like the initial wave created by the system speakers.

Like I said, it may be somewhat position dependent certainly as if you're sitting in a place with say a 70hz null off the rear wall, you'd tune the active to hopefully help that. Now if you moved and the null now existed at 60Hz, the 70Hz 'tuning' of the active device would need to be changed accordingly.

Bryan

I think it would probably be probably more helpful to think about it in terms of the steady state response instead of wavefronts. It seems that it acts to create a null at its location. Same as if you had a "perfect" bass trap at that location, with the result being the same in either case elsewhere in the room.

This device appears not to need be tuned as with the earlier Bag End device. Better DSP.

[JohnR]

Guys, I shot Clayton at Spatial an email trying to get more information on the product and will relay what I hear from him, here.

-Jim

Please do. I expect he doesn't want to give away too much about the DSP part.

[Rclark]

Well, as we know, bass waves don't spread out evenly in a room from any loudspeaker source. So for an active trap to work, I think it's radiation peaks need to more or less align with the peak locations from the main speaker.

To Rclark: I too would love to hear from the manufacturer of an active trap. In particular, I'd like to see waterfalls of several locations around the room, to see if the improvement is positional or not. This is a key piece of data that I've never seen presented. Also, usually (but not always), those of us in the business are the most knowledgeable about how these products work.

--Ethan

 
 That wasn't a shot at you, I was just hoping we could expand the conversation.