Author Topic: PSI Active Bass Trap  (Read 16529 times)

Offline ronildoq

  • Trade Count: (+2)
  • Full Member
  • Posts: 2211
Re: PSI Active Bass Trap
« Reply #15 on: March 27, 2018, 20:40 »
I assume it listens for the target frequencies then plays back opposing sound to cancel/tame LF.

Apologies if this is an ignorant question here - wouldn’t it “corrupt” the sound?
Also would the correction impact be sweet spot specific; or reasonably widespread?

I have. 44hz problem and don’t think I can fit anymore absorbers into my room.

Was wondering how effective is this treatment? Would love to hear from owners of this device.


Sent from my iPhone using Tapatalk

It doesn’t playback any sound or emit any noise Nor tame or corrupt the frequency response, it absorbs excessive energy in the room. Nasty standing waves that linger around in the room aka ringing. It is not broadband absorption, so it doesn’t take away or absorbs frequency on the upper levels like how those panels work or bass traps works.

The correction will apply accordingly to where u place the device, similar to bass trap. If u have a 44hz room mode, what u can do is run a 44hz pink periodic noise with mic at MLP. Then hold a SPL meter with you, walk around the house and find which spot returns the highest spl reading. Place this device there!

After that, play some nice movies and songs, then u will smile
 The above is assuming you only want the sweet spot to sound nice. Remember your MLP room mode is 44hz, other areas maybe 60hz... so it’s down to what matters to u. For me, only the sweet spot matters. Nobody else cares with the quality of details at home... lol

If you want the whole room to sound nice, then you will probably need 4 of these! Lol $$$


Sent from my iPhone using Tapatalk

Online Boxerfan88

  • Trade Count: (+1)
  • Full Member
  • Posts: 1568
  • Life begins at 7000rpm
Re: PSI Active Bass Trap
« Reply #16 on: March 28, 2018, 06:34 »
Thanks for the responses & sharing.

I’ve watched the video and it explains that it isn’t “noise cancelling” but “anti-wall”.

However some of the explanation seem to suggest “Low Freq noise cancellation” - especially the mic-speaker part (although he says it works only in the analog domain); and the subwoofer crawl way of identifying location to place device.

It’s certainly an interesting device for me to consider.


Sent from my iPhone using Tapatalk
Soekris dac1541 | DA&T A38  | Usher MD2+X616 | Orisun DD12 | Samsung PS50B850 | Elementa BAC 2500 |
Yammy RXA3030 | RPi3+Kodi | BDP-S5100 | PC+foobar2000 | Chromecast

Offline ronildoq

  • Trade Count: (+2)
  • Full Member
  • Posts: 2211
Re: PSI Active Bass Trap
« Reply #17 on: March 28, 2018, 08:19 »
Thanks for the responses & sharing.

I’ve watched the video and it explains that it isn’t “noise cancelling” but “anti-wall”.

However some of the explanation seem to suggest “Low Freq noise cancellation” - especially the mic-speaker part (although he says it works only in the analog domain); and the subwoofer crawl way of identifying location to place device.

It’s certainly an interesting device for me to consider.


Sent from my iPhone using Tapatalk
The best way is to try it at your listening place. maybe ask if can loan or demo at home. Because I feel if demo this at the studio, it won’t really matter because in your house, the modal frequencies are different and your walls interaction will be different too because of room dimensions. For all u know, just one unit would suffice. I know 1 is definitely effective for my room. But maybe 2 would be adequate , one front one back. Some thing like having 2 subs instead of 1 to take advantage of the modal frequencies from 15-150hz. Will post my findings soon after some measurements today.

Last night I popped in some music xrcd with all 3 avaa units turned on ..... blast ! fuyuuu.... tight like virgin ! Lol bass notes from the guitar, crystal clear and controlled ... I think drum Beats would be awesome.... haven’t tried that... I can hear clearly the bass decay times are much much improved

It just shows how important a room is for our HT, the speakers are only half the story. The room the other half. Speakers are now like being fed with steroids , clearly able to hear the true sound signature of the monitor audios and the seaton.... another level...


Sent from my iPhone using Tapatalk

Offline ronildoq

  • Trade Count: (+2)
  • Full Member
  • Posts: 2211
PSI Active Bass Trap
« Reply #18 on: March 28, 2018, 22:24 »
Alright, just had a half day off and could quickly do some measurements.

This is my Room Noise floor

Running a sweep with everything muted, it shows approx 43db level. This is the noise flloor at MLP in the Hall. You can see immediately  i have room modes at 23,27,40,58,90hz...


Below are the waterfall plots at MLP. First with just passive traps, second is with Dirac EQ on, 3rd with the PSI on.
you can see how it has cleaned up the decay times down to 20hz. The decay times much improved at 23hz & 27hz, 34hz, 38hz, 58hz, 90hz in green vs purple graph. The Blue is the original before dirac and before PSI active bass trap switched on. Done in GIF format so you can see the decay rates improvement without EQ, with EQ , with PSI.




Another way to see this is using the spectogram.

Graph with only dirac and bass traps


1.You can see clearly the ringing at 90hz, that doesnt end, goes all the way up beyond 1sec on the Y Axis
2.Decay times from 22hz to 35hz shows that it take approx 700ms to decay. This is not so desirable as generally we want soemthing between 200-500ms which is acceptable decay times, anything more suggest room treatment and corner traps.
3.58hz is also more than 600ms

With dirac and bass traps + PSI active bass trap


1.90hz ringing eliminated, if i point my cursor at 90hz, the time it takes to decay is 300ms
2.Decay times from 22hz to 35hz shows that it take approx 700ms to decay. This is where PSI comes in, see the entire range of 20-30hz now decays in less than 400ms. and up to 45hz, reduced from 700ms to 600ms. Improved nicely. This is the power of the PSI.
3.58hz down from 600ms to 450ms, very nice indeed.

In my earlier post, i mentioned using Pink Periodic Noise. That is the wrong one. Play a sine wave at the modal frequencies instead, then walk around the room with an SPL meter, when you see a spike in SPL readings for that frequency, place the PSI at that spot. Measure again to confirm if the decay times improves. After placement of the PSI, then we run Dirac EQ.

Dirac uses mixed phased filters, the results are natural sounding bass, mids and highs. Together with the PSI, this is quite awesome
« Last Edit: March 28, 2018, 23:03 by ronildoq »

Offline sevenz

  • Trade Count: (+16)
  • Full Member
  • Posts: 2368
  • home theatre lover :D
Re: PSI Active Bass Trap
« Reply #19 on: March 28, 2018, 23:23 »
Alright, just had a half day off and could quickly do some measurements.

This is my Room Noise floor

Running a sweep with everything muted, it shows approx 43db level. This is the noise flloor at MLP in the Hall. You can see immediately  i have room modes at 23,27,40,58,90hz...


Below are the waterfall plots at MLP. First with just passive traps, second is with Dirac EQ on, 3rd with the PSI on.
you can see how it has cleaned up the decay times down to 20hz. The decay times much improved at 23hz & 27hz, 34hz, 38hz, 58hz, 90hz in green vs purple graph. The Blue is the original before dirac and before PSI active bass trap switched on. Done in GIF format so you can see the decay rates improvement without EQ, with EQ , with PSI.




Another way to see this is using the spectogram.

Graph with only dirac and bass traps


1.You can see clearly the ringing at 90hz, that doesnt end, goes all the way up beyond 1sec on the Y Axis
2.Decay times from 22hz to 35hz shows that it take approx 700ms to decay. This is not so desirable as generally we want soemthing between 200-500ms which is acceptable decay times, anything more suggest room treatment and corner traps.
3.58hz is also more than 600ms

With dirac and bass traps + PSI active bass trap


1.90hz ringing eliminated, if i point my cursor at 90hz, the time it takes to decay is 300ms
2.Decay times from 22hz to 35hz shows that it take approx 700ms to decay. This is where PSI comes in, see the entire range of 20-30hz now decays in less than 400ms. and up to 45hz, reduced from 700ms to 600ms. Improved nicely. This is the power of the PSI.
3.58hz down from 600ms to 450ms, very nice indeed.

In my earlier post, i mentioned using Pink Periodic Noise. That is the wrong one. Play a sine wave at the modal frequencies instead, then walk around the room with an SPL meter, when you see a spike in SPL readings for that frequency, place the PSI at that spot. Measure again to confirm if the decay times improves. After placement of the PSI, then we run Dirac EQ.

Dirac uses mixed phased filters, the results are natural sounding bass, mids and highs. Together with the PSI, this is quite awesome

wow, the decay times improved quite a bit. Looks like it's quite effective. nice.... Good buy bro..

Offline ronildoq

  • Trade Count: (+2)
  • Full Member
  • Posts: 2211
Re: PSI Active Bass Trap
« Reply #20 on: March 29, 2018, 08:24 »
wow, the decay times improved quite a bit. Looks like it's quite effective. nice.... Good buy bro..

Yea u can see from spectrogram how hot I run the subs <60hz from the corresponding red orange coloured flames that matches the spl chart on the right. This is where the excessive energy accumulates when the gain on the subs are amplified below this point. A contribution from the hard knee house curve. Increasing levels=increasing decay times, correlated.

Bass traps can’t solve this <60hz region. Even if it can, there is no place to put in the  living room because it has to be huge for it to be effective to trap longer wavelengths down these frequencies

This is where I find this avaa device to be very effective for my case. I can hear the difference and see the actual statistical numbers. But yes, placement is important, put it in the wrong place and it does nothing!


Sent from my iPhone using Tapatalk

Offline ronildoq

  • Trade Count: (+2)
  • Full Member
  • Posts: 2211
Re: PSI Active Bass Trap
« Reply #21 on: March 29, 2018, 08:36 »
What I’m hearing now down Low at 20hz is slightly different. In the past when watching fast & furious scene, when he steps on the pedal and rev the engine, the rumbles are quite syok with subs energy and crowsons, textured and nice layering. But with this, I can now feel the pace of the driver hitting the accelerator pedal. As your car is in neutral and when u gradually hit the accelerator pedal, it gets louder and the driver seat rumbles. This is like that, I can feel the speed or amount of pressure when he steps on the pedal, increasing and reducing as he rev the engine. The details at 20hz is like so clear now. It’s like when u reduce the SPLs , u enjoy finer details but lose the punch/rumble. Increase the SPLs and u feel the punch but lose some details. This is both, with SPLs and with details... like that...so the subs can go louder now. But there is a limitation now, maximum effective absorption is up to 118db only....

I’m not so good with my description, but something like that... hahaha


Sent from my iPhone using Tapatalk

Offline ronildoq

  • Trade Count: (+2)
  • Full Member
  • Posts: 2211
Re: PSI Active Bass Trap
« Reply #22 on: March 31, 2018, 15:37 »


Bye bye demo unit.... I’m gonna miss u....

2 is just nice for my place, enough to absorb all the nasty standing waves. Bass is so tight it feels weird. Maybe I’ve grown used to the reverberation in my place...


Sent from my iPhone using Tapatalk

Offline kennyluck2000

  • Trade Count: (0)
  • Full Member
  • Posts: 251
Re: PSI Active Bass Trap
« Reply #23 on: April 02, 2018, 02:28 »


Bye bye demo unit.... I’m gonna miss u....

2 is just nice for my place, enough to absorb all the nasty standing waves. Bass is so tight it feels weird. Maybe I’ve grown used to the reverberation in my place...


Sent from my iPhone using Tapatalk

Ya you will not enjoy bass when is too tight and too clean...
But i thinks many will not agree with me  8)
« Last Edit: April 02, 2018, 02:37 by kennyluck2000 »

Offline ronildoq

  • Trade Count: (+2)
  • Full Member
  • Posts: 2211
Re: PSI Active Bass Trap
« Reply #24 on: April 03, 2018, 08:30 »
Yea Kenny, it feels a bit weird as I have grown accustomed to the reverberation in my hall. The vibrational energy lasts a tad longer but shortened when this is introduced

The power with this device is you can tweak the reverberation times to your preference. There is a knob on the device, a white knob to tell the device how much energy you want it to absorb. I set it to max absorption to see what it can do.

I don’t think bass traps can give us  that flexibility. This one does. The knob will correspond to decay times, I prefer somewhere about 300-400ms, feels just nice, not too much not too little

Offline ronildoq

  • Trade Count: (+2)
  • Full Member
  • Posts: 2211
Re: PSI Active Bass Trap
« Reply #25 on: April 03, 2018, 08:40 »
The other thing I find good is the uniformity in the decay times, that is very good, from 20-150hz, quite uniformed. This eliminates those “one note” bass, where certain frequencies seem to linger around longer, this is where u start to hear the details even at high SPLs

Offline Au

  • Trade Count: (0)
  • Jr. Member
  • Posts: 33
Re: PSI Active Bass Trap
« Reply #26 on: April 03, 2018, 08:49 »
Hi how much are the bass traps?  Pls pm

Offline kennyluck2000

  • Trade Count: (0)
  • Full Member
  • Posts: 251
Re: PSI Active Bass Trap
« Reply #27 on: April 03, 2018, 10:43 »
Yea Kenny, it feels a bit weird as I have grown accustomed to the reverberation in my hall. The vibrational energy lasts a tad longer but shortened when this is introduced

The power with this device is you can tweak the reverberation times to your preference. There is a knob on the device, a white knob to tell the device how much energy you want it to absorb. I set it to max absorption to see what it can do.

I don’t think bass traps can give us  that flexibility. This one does. The knob will correspond to decay times, I prefer somewhere about 300-400ms, feels just nice, not too much not too little

Yes the bass vibration energy had shorten is where it lost that feel.....  8)
Maybe we don't place the Active Bass Trap at the location where it's most effective, but instead place it wheres the bass is best feel for you....

Offline Jag

  • Global Moderator
  • Trade Count: (+2)
  • Full Member
  • *
  • Posts: 10807
Re: PSI Active Bass Trap
« Reply #28 on: April 03, 2018, 13:23 »
I’m interested.
Electronics : Denon 7200, MiniDSP Dirac 88A, Emotiva XPA-5 Gen2
ATMOS Audio : Martin Logan Ethos (L&R), ML Motif X(C), ML Motion 4 (14pcs surround spkrs)
LFE : Dual Rythmik FV25HP & Crowson Motion Actuator
Video : Sony VPL-HW55ES, Stewart Screen Studiotek 1.3
Source : HTPC
Fully automated HT via Alexa, Z-wave and Logitech Harmony Remote Control

Offline kennyluck2000

  • Trade Count: (0)
  • Full Member
  • Posts: 251
Re: PSI Active Bass Trap
« Reply #29 on: April 03, 2018, 15:38 »
Hi how much are the bass traps?  Pls pm

Had check with Sound Affair quoted for promotion price is $3.6k