Trinnov Strikes Back at DIRAC w Active Acoustics - But will it be as good as ART?

[gene]

Just weeks after Dirac officially announced Dirac Live Active Room Treatment, Trinnov has responded with its own announcement: a groundbreaking “active acoustics” technology that promises similar results. Trinnov’s new tech uses two large arrays of subwoofers to “effectively eliminate room modes,” and will be demonstrated at the ISE conference in Barcelona.

Editorial Note from Matthew Poes (Senior Technical Editor, Audioholics) about Double Bass Array
The Double Bass Array is an approach originally popularized in Germany and covered extensively on the AVS forum here in the states. It comprises an array of subwoofers placed along the front wall in a precise and symmetric arrangement. In theory this could be accomplished with as little as two subwoofers, but the distance between the subwoofers and their distance to any boundary defines the upper bandwidth over which they can produce a planar wave. A planar wave can be thought of as a cylinder-shaped wave instead of a spherical wave. The key to this is that the edges of the cylinder do not reflect. If you create a full planar bass wave from 100hz to DC, then there will be no reflections from the floor, ceiling, or side walls. There is no front wall reflection either since the array is mounted on the wall. This eliminates the vast majority of SBIR effects and room modes. What is left is only the length mode. If you copy this array on the back wall, delay the signal to the length of the room, and flip the phase, then the bass is fully canceled by the back wall. There is now no longitudinal modes either. Because half of the subwoofers in the room are used solely for cancellation purposes, you get no output gain, and in fact, because there are now no reflections, overall bass output in the room is more akin to outdoor bass levels with no room gain. However, given the large array requirements in the first place, this is rarely a major concern (and rarely are things absolute in acoustics).

A major drawback of the DBA is that the subwoofers must be precisely placed for the concept to work, irregularities in the room may lead to more complex reflections that disrupt the planar waves, and the number of subwoofers needed and their placement are both cost and space prohibitive. While a very effective tactic, this approach is rarely viable in even the most sophisticated custom theaters. Prior work by others have shown that DSP processing of the signal to each subwoofer can eliminate the precise location requirements somewhat, as outlined by Adrian Celestinos in his work on Controlled Acoustic Bass Systems (CABS) discussed here. Currently it is unknown the effectiveness of the DSP processing used by Trinnov’s new approach as patents were being processed as we went to press and no further details were possible. I have reached out to my contacts at Trinnov and will be doing a deep dive into this approach. I have requested the opportunity to hear this approach as well as possibly test it in my own room once the software becomes available. It is worth noting that Trinnov will not be providing this as a public beta, rather they will focus on specific projects that can support the double bass array. Further, the DBA approach is simply the first of many new ways in which bass acoustic control will happen. As compared to Dirac’s approach, the main drawback of the DBA is that it is only effective to the upper limit of the subwoofers, or around 80hz. Anywhere that bass directionality is needed would need to go to those speakers respectively and so no active control of reflections is possible. Passive treatment is needed there. By comparison, since active cancellation signals are being sent to all appropriate speakers, DIRAC is able to work up to 750hz potentially, eliminating the need for passive treatments below that point (at least in theory). It is possible that Trinnov will have similar capabilities in the future and I hope to continue to work with Trinnov to test each new release and bring my experience and understanding to our readership.

I also want to make a note about what this concept of active cancellation is doing qualitatively to the bass and why you should care. The most important first principle to understand is that bass reflections in a room are actually quite complex. We really need to divide the problem up into how low frequency reflections play into our sense of speciousness and envelopment and how low frequency reflections can create interference patterns that disrupt the sound quality perception. These are two different issues and the solution to one can potentially hurt the other. First let’s focus on this interference issue, which is what most people understand to be room modes and speaker boundary interference effects. Essentially, bass is bouncing off of the walls, floor and ceiling. As it then moves past other reflections and the direct sound, it creates constructive and destructive interference or peaks and dips in the response. Because this is a minimum phase phenomena it also causes bass to vary in the time domain, ringing at peaks and not at dips. Overall, the average time domain effect of the reflections also causes the bass to drone on a bit. This can cause a perceived lack of definition or tightness in the bass. It then makes sense that if we absorb or cancel all of these reflections, the net result is smooth, clean, and right bass at every seat in the room. Passive approaches are common but as many know, take up massive amounts of space and actually don’t work all that well below 100hz. You end up needing to give up a ton of space to effectively absorb these reflections. This creates a problem however, our sense of envelopment or feeling like we are inside of a larger room or space comes from lateral reflections. Both Trinnov and Dirac are largely eliminating these. Bass sounds like it is outside basically. This, in and of itself, is not a good or desirable thing. Now you could turn down the effective and keep some lateral reflections, but that still turns down the perceived sense of envelopment. I would argue this is not such a great problem. Perceiving that we are inside our room is not a great match to the actual venue we are trying to reproduce. Movies rarely take place in spaces that match our theaters and typically all of the spatial cues, including the low frequency cues, are encoded in the surround track. Musical events recorded in actual venues and recorded correctly (a big if) also contain all of the low frequency lateral reflections needed to give this sense of envelopment. Canceling the room out and reproducing it via surround speakers and surround subwoofers is not such a bad idea. However, most studio recordings, some live recordings, and probably some movies lack the low frequency spatial cues needed to perceive this sense of envelopment. It is likely that this concept of psychoacoustics is not that well understood or a major focus of mixing. For many, a sense of smooth, tight, and clean bass is far more important that the sense of envelopment, and so the sound quality improvement netted through wave cancellation will outweigh the detriment it could cause.

Read: Trinnov Strikes Back at DIRAC w Active Acoustics

 

[jeffca]

Both of these systems are a one size fits one room/system set up and can't be used in anything less than a very expensive pre/pro by Trinnov and Datasat (maybe one other).

As a proof of concept, they are impressive. As a viable product for anyone, but the most rich audiophiles, they are a failure. Perhaps, 10-20 years from now, audio processing in reasonably priced AV pre/pros will over enough power for this system.

Another idea would be an HDMI breakout box that can be added to your system. Even then, the low number of people wanting to buy that (we're talking maybe a few thousand units possibly) mean that the economics of scale might not apply. It could be pricey.

Honestly, software that could run on a mini PC or Mac that's also playing the movie file with two 8 channel pro I/O boxes would be much cheaper. Of course, set up and usage is not for the faint of heart.

And, then, you still have to have a bunch of subs, a place where to put them and all of the wiring. Nothing about these systems is cost effective or could be used in the average house.

Bottom line: neither Dirac or Trinnov are offering a solution that room treatments couldn't give you for just about the same or possibly better performance for much less than 10% the cost of the systems they are showing.

Does it work? Sure. Is it worth the price? Absolutely not. It's the audio equivalent of the Rube Goldberg machine that has 15 different stages to be triggered to catch a mouse.

 

[dlaloum]

At a very high level, it seems that Dirac-ART has been developed as a solution that can improve the rooms of most surround sound users.... where Trinnov is catering to the high end dedicated Home Theatre room market.... (no one is going to fit that many subs in their multi-purpose living space!)
Although Dirac's initial launch is on the high end Storm Audio processors, it is likely that it will find its way down to the mid / mass market area, Trinnov's solution has no pretense of competing outside of the "high end".

It will be interesting to see how the two differing solutions compare in similar high end configurations, but I cannot see myself purchasing a Trinnov solution, whereas I very much can see myself upgrading to DL-ART at some point, based on my expectations of pricing, and my budget.

 

[TLS Guy]

Just weeks after Dirac officially announced Dirac Live Active Room Treatment, Trinnov has responded with its own announcement: a groundbreaking “active acoustics” technology that promises similar results. Trinnov’s new tech uses two large arrays of subwoofers to “effectively eliminate room modes,” and will be demonstrated at the ISE conference in Barcelona.

Editorial Note from Matthew Poes (Senior Technical Editor, Audioholics) about Double Bass Array
The Double Bass Array is an approach originally popularized in Germany and covered extensively on the AVS forum here in the states. It comprises an array of subwoofers placed along the front wall in a precise and symmetric arrangement. In theory this could be accomplished with as little as two subwoofers, but the distance between the subwoofers and their distance to any boundary defines the upper bandwidth over which they can produce a planar wave. A planar wave can be thought of as a cylinder-shaped wave instead of a spherical wave. The key to this is that the edges of the cylinder do not reflect. If you create a full planar bass wave from 100hz to DC, then there will be no reflections from the floor, ceiling, or side walls. There is no front wall reflection either since the array is mounted on the wall. This eliminates the vast majority of SBIR effects and room modes. What is left is only the length mode. If you copy this array on the back wall, delay the signal to the length of the room, and flip the phase, then the bass is fully canceled by the back wall. There is now no longitudinal modes either. Because half of the subwoofers in the room are used solely for cancellation purposes, you get no output gain, and in fact, because there are now no reflections, overall bass output in the room is more akin to outdoor bass levels with no room gain. However, given the large array requirements in the first place, this is rarely a major concern (and rarely are things absolute in acoustics).

A major drawback of the DBA is that the subwoofers must be precisely placed for the concept to work, irregularities in the room may lead to more complex reflections that disrupt the planar waves, and the number of subwoofers needed and their placement are both cost and space prohibitive. While a very effective tactic, this approach is rarely viable in even the most sophisticated custom theaters. Prior work by others have shown that DSP processing of the signal to each subwoofer can eliminate the precise location requirements somewhat, as outlined by Adrian Celestinos in his work on Controlled Acoustic Bass Systems (CABS) discussed here. Currently it is unknown the effectiveness of the DSP processing used by Trinnov’s new approach as patents were being processed as we went to press and no further details were possible. I have reached out to my contacts at Trinnov and will be doing a deep dive into this approach. I have requested the opportunity to hear this approach as well as possibly test it in my own room once the software becomes available. It is worth noting that Trinnov will not be providing this as a public beta, rather they will focus on specific projects that can support the double bass array. Further, the DBA approach is simply the first of many new ways in which bass acoustic control will happen. As compared to Dirac’s approach, the main drawback of the DBA is that it is only effective to the upper limit of the subwoofers, or around 80hz. Anywhere that bass directionality is needed would need to go to those speakers respectively and so no active control of reflections is possible. Passive treatment is needed there. By comparison, since active cancellation signals are being sent to all appropriate speakers, DIRAC is able to work up to 750hz potentially, eliminating the need for passive treatments below that point (at least in theory). It is possible that Trinnov will have similar capabilities in the future and I hope to continue to work with Trinnov to test each new release and bring my experience and understanding to our readership.

I also want to make a note about what this concept of active cancellation is doing qualitatively to the bass and why you should care. The most important first principle to understand is that bass reflections in a room are actually quite complex. We really need to divide the problem up into how low frequency reflections play into our sense of speciousness and envelopment and how low frequency reflections can create interference patterns that disrupt the sound quality perception. These are two different issues and the solution to one can potentially hurt the other. First let’s focus on this interference issue, which is what most people understand to be room modes and speaker boundary interference effects. Essentially, bass is bouncing off of the walls, floor and ceiling. As it then moves past other reflections and the direct sound, it creates constructive and destructive interference or peaks and dips in the response. Because this is a minimum phase phenomena it also causes bass to vary in the time domain, ringing at peaks and not at dips. Overall, the average time domain effect of the reflections also causes the bass to drone on a bit. This can cause a perceived lack of definition or tightness in the bass. It then makes sense that if we absorb or cancel all of these reflections, the net result is smooth, clean, and right bass at every seat in the room. Passive approaches are common but as many know, take up massive amounts of space and actually don’t work all that well below 100hz. You end up needing to give up a ton of space to effectively absorb these reflections. This creates a problem however, our sense of envelopment or feeling like we are inside of a larger room or space comes from lateral reflections. Both Trinnov and Dirac are largely eliminating these. Bass sounds like it is outside basically. This, in and of itself, is not a good or desirable thing. Now you could turn down the effective and keep some lateral reflections, but that still turns down the perceived sense of envelopment. I would argue this is not such a great problem. Perceiving that we are inside our room is not a great match to the actual venue we are trying to reproduce. Movies rarely take place in spaces that match our theaters and typically all of the spatial cues, including the low frequency cues, are encoded in the surround track. Musical events recorded in actual venues and recorded correctly (a big if) also contain all of the low frequency lateral reflections needed to give this sense of envelopment. Canceling the room out and reproducing it via surround speakers and surround subwoofers is not such a bad idea. However, most studio recordings, some live recordings, and probably some movies lack the low frequency spatial cues needed to perceive this sense of envelopment. It is likely that this concept of psychoacoustics is not that well understood or a major focus of mixing. For many, a sense of smooth, tight, and clean bass is far more important that the sense of envelopment, and so the sound quality improvement netted through wave cancellation will outweigh the detriment it could cause.

View attachment 60020

Read: Trinnov Strikes Back at DIRAC w Active Acoustics

That Trinnov approach has been around from some years, and from what I have read is worse than useless. That sounds like a real dead end.

The best approach to getting good bass is ideal room dimensions and low Q speakers. I can tell you that it works. I am enjoying it right now. For the money of that complicated system, the money would be better spent rebuilding the room with ideal dimension ratios. Some people just love gratuitous complexity. The Trinnov system is a dead end and non starter. Go with the physical laws of nature and DON'T fight them!

 

[Matthew J Poes]

At a very high level, it seems that Dirac-ART has been developed as a solution that can improve the rooms of most surround sound users.... where Trinnov is catering to the high end dedicated Home Theatre room market.... (no one is going to fit that many subs in their multi-purpose living space!)
Although Dirac's initial launch is on the high end Storm Audio processors, it is likely that it will find its way down to the mid / mass market area, Trinnov's solution has no pretense of competing outside of the "high end".

It will be interesting to see how the two differing solutions compare in similar high end configurations, but I cannot see myself purchasing a Trinnov solution, whereas I very much can see myself upgrading to DL-ART at some point, based on my expectations of pricing, and my budget.

I think this is overstating what passive acosutics can do to an extreme. This product will be available on cheaper receivers. There seems to be a misunderstanding this requires subwoofers everywhere. There is a difference between benefits from and requires. Having more speakers and subs in more locations increases the benefit. However it works just fine with a normal system. Even a modest 5 channel system with a pair of subs could see fairly sizable benefits.

Dirac has built in protection to help avoid overloading the speakers and clipping the amp. You can manually override this and that could be an issue. However if used on a typical receiver it could work fine without big issues. What happens is that the e degree of cancelation is simply limited to stay worth in the range of the system. During dynamic peaks it may have short momentary periods where the response is just not quite as good as it could otherwise be.

I would love to try to figure out just how many Sabins below 700hz are needed to equal what this active Cancelation method can do. I probably will do that for a video. However it effectively makes the room anechoic at low frequencies. You can adjust it down if you want, but it will fully cancel reflections if you want. To achieve that with off the shelf absorbers is impossible. However if we did something that approximated the degree of improvement it offers, I just went to GIK’s website to price it out. That I would consider a cheap option. Given how significant the effect of ART is, I would argue you need to cover a sizable portion of the side and back walls and use the soffit traps in each corner floor to ceiling as well as along the front, back, and side wall ceiling/wall interface. All of that still wouldn’t equal enough absorption to actually null out the reflections as well as ART can but it would be very good. That’s about $9000 in bass traps. A Storm is $15k or so and you get more than ART for that. Acoustic treatments are just not efficient enough at low frequencies. Active correction like this is far more efficient.

 

[Matthew J Poes]

That Trinnov approach has been around from some years, and from what I have read is worse than useless. That sounds like a real dead end.

The best approach to getting good bass is ideal room dimensions and low Q speakers. I can tell you that it works. I am enjoying it right now. For the money of that complicated system, the money would be better spent rebuilding the room with ideal dimension ratios. Some people just love gratuitous complexity. The Trinnov system is a dead end and non starter. Go with the physical laws of nature and DON'T fight them!

There is more coming on Trinnov. You are assuming it to be far simpler than it is. It’s not just a double bass array. There is additional sophisticated processing as well. DBA is just a part of the equation.

As for DBA’s being useless, I don’t know where you heard that. It’s extremely effective. Its biggest problem is that it’s very difficult to implement correctly. It effectively removes all low frequency reflections. You end up with only direct LF sound. No modes. The Q is the speaker and the dimensional ratio couldn’t dream of doing that. Room ratios just help avoid compounding modes on top of each other. You still have just as many as you would have. It’s just easier to deal with when they aren’t on top of each other.

I am not totally sold on this myself but not for the reasons you bring up. I am absolutely confident it is an extremely effective means of improving bass. You simply couldn’t get bass that decays as cleanly, is as smooth, or has as large of a sweet spot in any other way. No reasonable amount of acoustic treatment is going to equal it. When the SBA was developed it took something like 2 feet of low density insulation covering the entire back wall to effectively absorb the reflection and it still wasn’t as complete as the DBA cancelation.

Trinnov is being very tight lipped about the new tech and nobody knows very much. I’ve talked to them and they have promised to fill me in soon. Once I have something I can share I will. I also want a demo. I couldn’t make it to ISE and am not sure when the first US project using it will come. Who knows, maybe I can design it. Trinnov is my go to processor generally for custom home theaters so I just need to convince a client they need a massive number of subwoofers.