Hi, I have been using a pair of the PSI AAVI C20 active bass traps for a couple of years and find them a great contributor to my system. While frequency measurements are easy to make and undertsand I think they are not really usefull when evaluating these products. What these bass traps do is reduce reflected bass making the direct bass more prominent. The overall effect is much more clarity, resolution and impact (’snapp’ or perceived speed) in the bass. I speculate that when reflected bass interacts with direct bass the result is a ‘smeared’ sound with reduced impact.
Having the PSIs in the right place makes it easier to pay attention to how the music opens up first, as this goes hand in hand with the bass cleanup, ..for many it is difficult to hear the more defined sub-bass..
Thanks for the review there are very few on this product. My two C214 work well. You nailed it, they are more expensive but I would’ve never had room for actual passive bass traps in my non-dedicated listening area. They are pretty steady and reliable, but I wish the Wi-Fi connection was less finicky to set up and for firmware updates.
Thank you, Tom, for this thoughtful, detailed, measured and very accurate review! My room has problematic room modes at 45Hz and at 60Hz. I use three AVAAs which significantly reduce the reverberation time at those frequencies. I highly recommend AVAAs! It is great that TAS is letting more people know about them! With warmest regards, Ron
This is superb content that just can’t be delivered in TAS textual formats. Well done. Can’t wait for the rest of the series and any comparisons to DIRAC and such. Substack here I come.
I got fed up with not having good sound and buying new gear doing nothing to improve things, so I learned about acoustics. While engaged in long term mortal combat with room modes I had an epiphany. I created my machines out of stuff I had left over from other projects and a few new bits. I turned it on and dialed it in, which took some work, more so because I'm using imperfect solutions to the problems, parts wise. I now have a blend of passive and active bass management and the rooms 26 dB primary mode is maybe 5 dB now, maybe not even that. Banishing the room modes is pretty much the most important thing to achieve, it effects the sound at all frequencies. Good video, solid info and a solid analysis of the products performance and your results seem right in line with what I have read about Nelson Pass's version.
Honest about the history (and effectiveness) of bass traps. Hence the lack of these reviewed in TAS, in the last 25 years. Now that they've improved, TAS is there....
I have a room full of the 214’s. Their impact on my system can not be understated. I had a significantly audible bass problem in my space. These fixed it. Not cheap. You can hear their impact easily be forgetting to turn them on and wonder what’s wrong with my system. 😂
I am another satisfied user of the PSI AVAA C20 active bass traps. I have a pair that have improved the bass performance in my room enough to allow me to eliminate the passive bass traps I have used in the past. The room is now audibly and aesthetically superior to its previous incarnation. What analysis software are you using? Room Equalization Wizard (REW)?
If your measurements are accurate the overall response below 100 hz. looks worse with the AVAA than without, as it appears to have substantially increased the nulls at 58 and 89 hz. The difference between the peaks and nulls remains the same at approximately 12db. Different room positions may have provided better results attenuating the standing waves resulting in said nulls.
Totally agree that different room positioning may have helped. I do think peaks are more audible than dips, and even more noticeable are the decay elements, so one has to listen to determine what is better. The first room, which I had access to for < a day, was mainly to see if locating the AVAAs where they easily fit would yield some difference.
The cost is super high, but the way that PSI Audio is setup, I understand that you are spending money on handmade analog excellence. What is cool about the C214's is that they lower the time domain characteristics of bass. I don't know if I missed it, but it would be very cool to compare the time domain characteristics of passive bass traps to the PSI traps. More measurements and research is needed. The cost to performance ratio on this product is NOT GOOD, hands down. Passive treatments that are targeted toward a specific problem in the frequency response + good old elbow grease and calculations still feel like the best bang for your buck. Passive is still the way to go, in my opinion, until the prices come down from the stratosphere, on the AVAA C20's and C214's. More competitors are needed in this space so that companies get into price lowering wars.. I'll come back in 5 - 10 years..
I have 11 panels in my room. Using Robert Harley's recommendation for curved diffusors (stellar product) and mid-high absorption (same company) problems solved just not the bass. The bass tube traps are $500-$750 each. I'm guessing I'll need? 8 of them. The joys of bass :)
There is a lot of interest in room treatment. There seems to be a fairly common approach of sticking tubes in corners and some panels on walls. There is another youtuber, @AcousticFields, that is nothing but room treatments from small listening rooms to churches and recording studios. He uses a very different, very physics and math based approach. It would be interesting to see some reviews at that level. This being a good start.
Would be interesting to get an earlier product, the Bag End ETRAP-1 which has been out for many years so most would have forgotten that it is still a listed product reviewed many years ago.
First off, in a small room, you have room modes (pressure based problems) and reflections (which are NOT pressure based, but based on reflections from hard surfaces like walls, windows, and items in the room that reflect higher frequencies. I would go with a cutoff point around 100Hz. Below 100Hz, I would recommend PRESSURE based absorption, and for reflections, I would recommend velocity based absorption, Acoustic Foam (a good brand) would be recommended that's actually designed for treatment of music and speech. Acoustic foam brands are NOT equal. There are different densities of foam, different cell sizes, which have different absorption coefficient curves. But, there are three TYPES of room modes. 1. Axial Modes - Unwanted pressure between 2 parallel surfaces. Either front to rear, side to side, or floor to ceiling. They are the highest in amplitude and the most audible. 2. Tangential Modes - Unwanted pressure between 4 surfaces. These are less pronounced, essentially lower in amplitude measured in dB, less audible than Axial modes. 3. Oblique Modes - Unwanted pressure between 6 surfaces. They are even less audible than Axial or Tangential. Now, if you want to calculate the room modes, and look at a 3D representation of where the modes reside. I would use AMROC Room mode calculator, but they will not tell you what the dB level because that's dependent on the amplitude dB of the source within the room and the listening location. But it will at least give you an idea of what frequencies are giving you the biggest problems and where they are located. Here's a link. amcoustics.com/tools/amroc?l=23&w=19&h=9&st=false&so=false&ft=true&r60=0.6. You'll notice that I only have the Axial mode represented, but you can play around with the application and check to see what the Tangential and Oblique modes are and where they are located, but I would worry more about Axial modes first. First you have to find out what frequencies are the problem, where they are located and then you have to choose a product that's actually going to absorb as much of the problem frequencies and then get as much surface coverage. 50% to 70% is recommended for the treatment of Axial modes. These active room treatment simply do NOT absorb as much in the lower frequencies than other products on the market. I wouldn't recommend them. I looked at their curve they have on their website and while they decreased some frequencies, but they also increased other frequencies, that's the problem with active speaker based absorption. Sorry, but I would pass on these products for the amount of money they are charging. I don't know what bass traps you are comparing to the AVAA, but you aren't looking at very good ones. Not all "bass traps" have the same absorption coefficient curves. Also, I would NEVER, EVER, EVER recommend putting bass traps in the corners. That's simply a myth that's perpetrated through the industry.
@@3rdeye1983 There are Three types of room modes. Axial, Tangential and Oblique. Axial is unwanted pressure between 2 parallel surfaces, Tangential is unwanted pressure between 4 surfaces and Oblique is unwanted pressure amongst all 6 surfaces. Now, in terms of their amplitude of severity Axial modes are the highest, Tangential are 2nd highest, and Oblique are the third. Meaning, that if you treat the Axial modes, then you will make the biggest impact in terms of treating the unwanted pressure. Now, the second part is figuring out which frequencies you have the most difficult problem with starting with the lowest. If you treat for the lowest, then the rest start to fall into place as they tend to be harmonics of the lowest fundamental. SO, how do you know what frequencies are giving you the problem? Two ways, you can either measure the frequencies around you the room to figure out where these modes are and with which frequency. It's time consuming but you can layout the pressure zones in terms of frequencies, amplitudes and location. How to pick the most appropriate treatment. You can look at the absorption coefficient curve to figure out which product is going to absorb the most as which frequencies you have the most problems with. Most small rooms have room mode problems in the 30hz to 50hz range and you can type in the dimensions of your room into a room mode calculator like Amroc and it will show you the frequencies and their locations. Axial modes are generally along the entire length of the surface Front/rear, side, floor, ceiling. And the more surface coverage of the treatment, the more absorption and the better you're going to treat those problems in the areas they reside. I hope this makes sense. If you look at corners, that's only about 5% room surface coverage at most and it's only going to absorb a VERY, VERY small amount of the room modes. Surface coverage is key when treating room modes and reflections. The more surface coverage of the right treatment in the right location will yield the best results.
@@Oneness100 I'm aware of all that. I was referring to your statement that the corners are not the best place to put bass traps which is completely wrong. Corners are the best place my friend
@@3rdeye1983 Sorry, but there's not enough surface coverage and you aren't going to absorb enough of the Axial modes, which are between 2 parallel surfaces NOT 2 parallel corners. I've seen before and after measurements of putting low frequency absorption devices in the corners, they hardly do anything. I've seen measurements of proper low frequency absorption along the wall surfaces and there's a HUGE improvement in many cases can be double digit dB attenuation. It all depends on the product, how much surface coverage, etc. It's all about surface coverage and putting the right type of treatment in the right location. PERIOD. I highly suggest you THINK about what you're doing here. 2 parallel SURFACES vs 2 parallel corners. Which room mode talks about 2 parallel corners? Not Axial. Axial have THE largest in amplitude (dB) peaks and nulls than Tangential and Oblique. I think you've been brainwashed by companies that simply don't understand how to treat Axial room modes and the importance of treating those types or room modes. Companies like to sell you products for the corners because you typically don't have anything there, but that doesn't mean it's going to solve the problem.
@@3rdeye1983 Here's a method to prove my point. Put a 30hz then 40hz then 50hz then 60hz sine wave at 80dB measured at the listening position in your room. Go around the perimeter of the room (without any low frequency treatment) and measure the dB starting at the corner and taking measurements about every 3ft until you go around the room. See which frequency measures the same as the listening position and which measure above or below the listening position and mark where in the room those measurements are. IF, your assumption is correct, then ONLY the corners would have an increased dB at which frequencies you have a problem with and that no where else with the perimeter of the room would you have any increase or decrease in dB at which ever frequencies your room has problems with. I can guarantee you that you will find locations around the perimeter of the room that are NOT in the corner, with increased dB at the frequencies your room dimensions have a problem with, and you need to have treatment that will absorb as much as possible at those frequencies at those locations. Put the dimensions in your room in Amroc mode calculator and you can look at each frequency and a 3D viewer to see which wall surfaces the frequencies are located and then you can measure with a dB while putting a sine wave of each frequency through your system and compare the dB to the listening position.
I'd suspect typical viewers of this content aren't the best target for AI generated audio related b-roll eye candy. Dig this product, ... a small version of Nelson Pass' Phantom Acoustic Shadow (powerfully effective). I think what's key here is tighter decay times, and any freq response gains are just a bonus. Interesting, the secondary room/speaker measurement, ... appears to illustrate a well defined SBIR null around 100hz (correlates to the drivers being ~3 feet off the front wall boundary, but the math is never clean with sidewalls etc.).
I thought the problem of bass was solved with a sub array (4 or 5 subs scattered across the room)? Tom, have you tried this? Comparing the effects of a sub array with the effects of active traps would make for an interesting video.
It would be a good test. The 4 sub arrangement is designed to smooth out bass by spreading the effects of the different resonances out more than with, say, one sub. But the resonances are still there, so I would think bass traps are still a thing, albeit maybe less necessary. I also think many rooms will simply not allow a 4 sub arrangement, but that is a practical matter for each user to decide.
Multi-sub approaches benefit the freq domain, but not time domain. Spreading subs around smoothes the FR in an averaging manner, but does nothing addressing decay times, ie., damping the energy over time. That requires some effective LF damping/bass trapping.
In studio - probably maybe sometimes. At home - useless. You'd be much better off with a pair of subwoofers and a DSP board allowing you to invert, delay and FR adjust bass (to "cancel" the reflection). You shall put them into the opposite to main subs' corners. BTW, consumer grade base traps are distilled snake oil.
I sometimes wonder if the people involved in this 'channel' can remember what pleasure from listening to great music really is -- or maybe WAS. Obviously, the whole "high end audio" phenomenon goes through phases and fashions and some of us are old enough to remember satirical cartoons about stereo bores -- perhaps because we were such, or in danger of becoming part of the infernal club. Odd that it tended then and now to be very much a 'boys' club' of a particular sort when probably over half of professional classical musicians from the millennium have been female. Could it be that those who are deeply involved in music making use their ears and would laugh at much of the measuring and theorizing preoccupying sites such as this one? There are many and the stern gravitas and reverential tones and phrases used are objectively hilarious. Way back (I am old) there were obsessions with tracking weight and the hunt for the magical 1 gram, tone arms with gloopy liquid in baths (which got filthy) and swearing on a stack of Bibles that expensive speaker wire was 'IN' or 'OUT' for use with some pieces of equipment or said equipment was somehow being insulted. Of course "high end" was always high price and well made objects of any sort will, by their nature, be expensive. However, there is a difference between justified price and extortionate and in recent years the latter category has swollen and some products have appeared which can hardly justify their existence in relation to music and a given place where that music is played. I do not say "heard" because when human auditory apparatus is self-attuned to permanent TESTING MODE it is a matter of fact that music is a long way down the ladder of importance. When physical equipment needs software updates one must question why the original product was not good enough upon purchase. And what happens when a company goes bust and there is no further support? Much the same applies to streaming because, no matter how the cake is cut and other components do various jobs from to source to output we are stuck with variations and adjustments [= tampering] from the source end. Compression is a given but various electronic or electrical adjustments cannot improve upon inherent limitations at the source end. The so-called revival of vinyl is not the same as vinyl analogue records of last century. Look up how modern vinyl records are made. The most profound fooling is fooling oneself.