Author Topic: PSI Active Bass Trap  (Read 13587 times)

Offline ronildoq

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PSI Active Bass Trap
« on: March 26, 2018, 14:00 »
Yesterday i hosted some of our fellow members to test out Dirac Live and the Seaton F18s. In the process, we were introduced to this Active Bass Trap device.

http://www.psiaudio.swiss/avaa-c20-active-bass-trap/

We all know that its very difficult to treat freq below 80hz and you will need extremely huge bass traps placed at trihedral corners. Not anymore, this active bass trap does its job. How do i know? Well, first by listening, then by measurements to confirm the decay times. This device actually absorbs a lot of the standing waves in my living room without altering the freq response. The absorption is down to 20hz region. We didnt have the luxury of time to test out with placement. So i was handed 2 units to test out the device this week. i will post alll my findings soon. What i have just learnt in my process is this.

1. the device has a limitation in absorption, it absorbs standing waves up to 118db and then the signal clips, as it decays, it resumes the absorption, but at this point, the absorption surface is reduced.
2. as with subwoofers, the placement is key. the Question then arises on how and where to place this device. For starters, everyone will recommend corner placements. Because that is where most of low freq energies accumulates.
3. Armed with a UMIK-1 and REW, you need not place it there. What you can do is this.
a) Place the mic in the MLP, run a sweep from 15-200hz
b) Under Rew EQ settings, Find Modal Frequencies. This will tell you the room modes in your place and the T60 times
c) Once you have the modal frequencies, list it down, ie 30hz, 58hz,90hz (the ones in my room)
d) Play a pink periodic noise at 30hz, while its playing, walk around in the room and determine which area has got the strongest bass.
e) Repeat the steps for 58hz, 90hz or any other modal freq up to 150hz. Jot down which place has the strongest bass energy.
f) Place the active bass trap at this location. This will absorb all the standing waves and the device will be very effective.

Again the Key to this is placement.

The device doesnt alter the amplitude response. Rather, it just absorbs excessive energy. the result is Tighter Bass with improved ringing and decay times. This is audible and with REW to confirm this, i can safely conclude that the product works!! Its like magic. Some will argue that EQ will be good enough. But i can assure you my EQ with Dirac is Flat down to 100hz and i still see a nice improvement in bass performance. So so good the textured bass with this switched on and switched off. I can further crank up the gain now on the sub channel with the ringing reduced. Coincidently i saw one unit on the resale section and grabbed one., so i now have 3 units at home to play around with.

I will share more details soon. this device is damn good, does its job, but very expensive $$, made in Swiss.


Offline ronildoq

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Re: PSI Active Bass Trap
« Reply #1 on: March 27, 2018, 08:35 »
Before I acquired this device, I had a serious doubt . Because in theory, if you attenuate the peaks and improve the amplitude response, the decay and reverb times improves. Yes this is correct as can be seen from the article from Audioholics.



However if you read carefully, it doesn’t mention how the decay times are improved over a given bandwidth. What this device does is it improves not only the reverberation times, i have discovered that it does it uniformly. Meaning that from 20hz to 150hz, most of the frequencies along this band decays at 0.25ms in a uniform fashion. (You can tweak reverb sensitivity) . EQ with Dirac or biquads doesn’t solve this. I still see a significant improvement in decay times with Dirac on.

I have 2 corner traps from aural aid, 2 MOAB and 5 hybrid panels. The hybrid panels are good for treating first reflection points, but the bass traps does nothing from 100hz down to 20hz. I confirmed this personally 2 years ago integrating rythmik and KK. This PSI stuff does it! Amazing stuff. It is a solution for bass problems caused by room modes. The best part is my room is still alive. The bass pounds stops, pounds again, stops, pounds again and stop. Such is the quality. This also helps with the higher frequency as suddenly everything is so tight and controlled. It is easy to compare by switching the on and off button on the psi.

Passive treatment is still required, but this is a step forward for bass solution without having huge gigantic corner traps etc. Plus u can bring this device with u anytime, anywhere. Up till last year I think we don’t have a solution for that other Than placing Huge bass traps and tons of it.

Having said that, I still find it pricey...but it’s solution and quality is why I think the price is there. Good stuff indeed.

Still in the process of gathering more data, let’s see how it goes... hopefully 1 unit at my place is all I need to have uniform decay times from 20-150hz

Will post my findings soon

Here is a pic of the second hand unit I got






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Offline francishuang

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Re: PSI Active Bass Trap
« Reply #2 on: March 27, 2018, 08:54 »
This active bass trap do as what it said it does.  :)
Gd stuff
Shindo is Music

Offline ronildoq

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Re: PSI Active Bass Trap
« Reply #3 on: March 27, 2018, 08:57 »
This active bass trap do as what it said it does.  :)
Gd stuff


Nice u r using it to. How was the improvement at your place ? Significant enough to tell the difference yea? How many u r using ?


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Offline nfnc

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PSI Active Bass Trap
« Reply #4 on: March 27, 2018, 09:37 »
Thanks for the detailed post. Looking forward to reading more. 

The impact of the PSI AVAA at the dealer's place was clear enough. Your system though is the first domestic (there may be others who don't post on forums) system that shows that it works even with a system that employs EQ / DRC and room treatment.

Looks like you were the one that had faster leg faster hand on the pre-owned unit

Offline kennyluck2000

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Re: PSI Active Bass Trap
« Reply #5 on: March 27, 2018, 09:50 »
This active bass trap do as what it said it does.  :)
Gd stuff

francishuang, how much you bought when new?
« Last Edit: March 27, 2018, 09:52 by kennyluck2000 »

Offline ronildoq

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Re: PSI Active Bass Trap
« Reply #6 on: March 27, 2018, 13:25 »
Thanks for the detailed post. Looking forward to reading more. 

The impact of the PSI AVAA at the dealer's place was clear enough. Your system though is the first domestic (there may be others who don't post on forums) system that shows that it works even with a system that employs EQ / DRC and room treatment.

Looks like you were the one that had faster leg faster hand on the pre-owned unit


Fast hand fast leg because I took measurements to confirm the efficiency of the product. I didn’t believe initially until I heard it at my place and confirmed with actual data. I will share more this week after my experiment work with decay times.

Many will tell u have bass traps at corners etc, can the gigantic bass traps really help? Probably a bit , even then, absorption of standing waves down to 20hz, very very hard unless u have a dedicated HT room built from scratch like those from rob hann or huge bass traps.

I was playing the gravity scene at -14 reference , but the psi started clipping with a red light indicator on off... we were watching it with SPLs >118db pressurising the entire living room, still I didn’t find it to be overwhelming and loud, I could clearly distinguish the textured layers at 118db on the seatons.

The thing with this is it helps with the room modes. When the room modes are taken care of, the entire system just goes up a notch. Even the higher frequencies sound beautiful, what an eye opener for me.

I have all 3 units avaa spread out, just like how I placed my subs.

Will post more soon... very exciting this device


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Offline kelvinsin

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Re: PSI Active Bass Trap
« Reply #7 on: March 27, 2018, 13:35 »
Why the seller sold this baby to you? Upgraded to better weapon?
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Offline ralfale

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Re: PSI Active Bass Trap
« Reply #8 on: March 27, 2018, 13:52 »
I'm with ronildoq when the psi was plugged in to show the before n after effect. This is really for serious folks who are after perfection. At times, even for serious folks they may not have the luxury to place big bass trap. This little device is certainly revolutionary and the best part is it is more effective than bass trap.

This product should certainly be part of any room treatment plan, with diffuser n absorption for first reflections and psi for anything lower than 150hz.

Highly recommended.
« Last Edit: March 27, 2018, 13:55 by ralfale »

Offline ronildoq

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Re: PSI Active Bass Trap
« Reply #9 on: March 27, 2018, 13:59 »
Why the seller sold this baby to you? Upgraded to better weapon?

Not sure why. But he mentioned he will be going overseas for work for a Long time and won’t require this. I absolutely love the quality it brings to my room. If I decide to move my HT to common room. I can just plug it in anytime. Don’t need any big bulky bass traps that may not even work! Lol


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Offline sdds

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Re: PSI Active Bass Trap
« Reply #10 on: March 27, 2018, 14:16 »
Totally agree , this device is the real deal to replace passive bass traps . Moreover , most of us would not have the luxury to install big bass trap or design bulit delicated music room or home cinema . The downside is the pricing .

Offline Boxerfan88

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Re: PSI Active Bass Trap
« Reply #11 on: March 27, 2018, 15:00 »
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.


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Offline econav

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Re: PSI Active Bass Trap
« Reply #12 on: March 27, 2018, 15:46 »
You can buy a copy to read up in detail,
http://www.aes.org/e-lib/browse.cfm?elib=16909
How the pro-audio ppl doing it ? ya there are other product out there............
We are not second hand dealer , all items we sell as used are tradedin from our customer and we don't rate it condition but for the buyer to decide on it own.
From time to time we may sell off some New but open up used for rental/standby/loan items and to ensure they cant be sold as Brand new , we will dispose off the box.
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Online sevenz

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Re: PSI Active Bass Trap
« Reply #13 on: March 27, 2018, 16:54 »
Thanks for sharing this. Looks very promising for waf.

Possible to post some b4/after graphs? =)

Offline nfnc

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Re: PSI Active Bass Trap
« Reply #14 on: March 27, 2018, 18:22 »
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?

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https://m.youtube.com/watch?v=fw2Oj7QB0FQ

The above video would be quite enlightening. Look out for the Q&A session at the end of the presentation.