Andrew Quint Reviews the Unique BACCH-SP Stereo Purifier

[RichB]

This is a video review of a crosstalk processor.

Andrew Quint Previews the Unique BACCH-SP Stereo Purifier

You can read Andrew's full review of the BACCH-SP in our December issue, now available in print and digital. Andrew Quint previews the unusual, but no

www.theabsolutesound.com

It is very slow moving; this is a product with an analog input version and digital version priced at $23,800 and $19,800.
The product comes with an iPad, camera, and ear mounted microphones and takes measurements in the listening position and two others approximately two feet apart.
The claim is to eliminate crosstalk with a filter providing greater:

• Envelopment
• Proximity and Depth
• Spatial Extension
• Resolution

This is backed up by actual measurements, just kidding.

You might well guess the target audience.
Andrew is in no danger of going viral

- Rich

 

[Joecarrow]

I’ve heard the Bacch SP playing through a set of Kef LS50, and it was remarkable. How do you measure it? I’m not sure. I can tell you that binaural recordings were spooky real, with sounds moving around very clearly in 3D space and moving above the ceiling and below the floor, with pretty much 360 degree envelopment. As wild as the claims may seem, I do feel like it delivers on them. Is it worth the price? Not to me. I’d gladly run it if I had it though.

 

[Zoomer]

More in-depth discussion and user reports:

BACCH4Mac Pro Edition - For those considering BACCH

Thinking of getting BACCH? My strongest advice is to JUST DO IT AND DO IT NOW!! This is for those considering using BACCH dsp (BACCH) in their system but are unsure if it will work for them. I primarily wanted to give you an overview of my experience using BAACH4Mac without re-stating...

www.audiosciencereview.com

 

[ARQuint]

This is a video review of a crosstalk processor.

Andrew Quint Previews the Unique BACCH-SP Stereo Purifier

You can read Andrew's full review of the BACCH-SP in our December issue, now available in print and digital. Andrew Quint previews the unusual, but no

www.theabsolutesound.com

It is very slow moving; this is a product with an analog input version and digital version priced at $23,800 and $19,800.
The product comes with an iPad, camera, and ear mounted microphones and takes measurements in the listening position and two others approximately two feet apart.
The claim is to eliminate crosstalk with a filter providing greater:

• Envelopment
• Proximity and Depth
• Spatial Extension
• Resolution

This is backed up by actual measurements, just kidding.

You might well guess the target audience.
Andrew is in no danger of going viral

- Rich

I have to agree with the "slow moving" characterization. This is the first one of these videos I've made and it was especially tough (for me) to do after agonizing about every word for the 4500 printed review that'll be in the November issue. Writers are instructed to send one uninterrupted, talking-head type video and a two-minute "reel" of product shots. I'm hoping to do better next time, with a less complicated product.

In terms of measurements, as you might imagine, Dr. Choueiri is big on them and did many to guide installation and experiments with room treatment. The amount of cross-talk cancellation achieved depends a great deal several factors but the most important (in my opinion) is the radiation pattern of the loudspeaker. "Directional" designs - electrostatics, dipoles, horns with waveguides, etc - fare better than speakers with a omnidirectional radiation, such as my usual Magicos. I'm now working on a review of a Wolf von Langa speaker that's a 2-way with an AMT tweeter and a field-coil woofer - it functions as a dipole. The results with the BACCH-SP adio are excellent and substantially better than I could get with the Magico M2s, even with extensive room treatment and moving the speakers to a more near-field position.

The BACCH software does report average XTC and, for my room and equipment, this ranged from around 6 to 11dB.

I think this is a remarkable product, designed by a capable scientist/engineer yet easy to use by audiophiles with varying degrees of technical sophistication. Theoretica doesn't have a lot a dealers at this point but Dr. Choueiri makes it to a lot of audio shows and does a lot of demos. Try to hear the filter if you can. There does seem to be a fair amount of interest among audiophiles: As unexciting as that video is, there have been close to 1000 views in a little over a week. That's good for Theoretica, I hope.

Andrew Quint

 

[Dialectic]

I still haven't heard anything that is more impressive than BACCH, and that's why I use it in my system, despite the added complexity. It has ruined conventional stereo listening for me.

It's very much a science-oriented product...

 

[RichB]

To be fair, REQ software (Dirac and others) that are well based in science, have to post measurement verification.
Video calibration has this feature. I have tried Dirac many times and it does something I don’t like to the soundstage.
Even engaged in a null settings (no changes) the audio path alters the sound, so like many similar products, the predictive charts provide confirmation bias.

If a user runs a correction product until they like the predictive charts and sound, that is wonderful. It is however, not the pinnacle of science.
Their results are subjectively better, just as mine are when I compare results the non-corrected sound.

- Rich

 

[Dialectic]

To be fair, REQ software (Dirac and others) that are well based in science, have to post measurement verification.
Video calibration has this feature. I have tried Dirac many times and it does something I don’t like to the soundstage.
Even engaged in a null settings (no changes) the audio path alters the sound, so like many similar products, the predictive charts provide confirmation bias.

If a user runs a correction product until they like the predictive charts and sound, that is wonderful. It is however, not the pinnacle of science.
Their results are subjectively better, just as mine are when I compare results the non-corrected sound.

- Rich

To be fair, in your first post, you criticized BACCH for not being backed up by actual measurements. Others point out that it is, so now you change the standard and suggest that the effect of BACCH must be due to confirmation bias.

I love the Toole book and have used much of the traditional Toole/Olive/Harman International conventional wisdom in placing my speakers and applying room and headphone EQ.

However, traditional stereo and multichannel audio has severe limitations (principally with images collapsing into one channel or speaker) that only become obvious once one hears a system with crosstalk cancellation. The first time I heard a BACCH system (incredibly to me now, in March 2015), it was clear that much of the Toole/Harman conventional wisdom had gone out the window.

Many papers and other resources such as speaker measurements can be found at https://www.princeton.edu/3D3A/

 

[RichB]

To be fair, in your first post, you criticized BACCH for not being backed up by actual measurements. Others point out that it is, so now you change the standard and suggest that the effect of BACCH must be due to confirmation bias.

I love the Toole book and have used much of the traditional Toole/Olive/Harman International conventional wisdom in placing my speakers and applying room and headphone EQ.

However, traditional stereo and multichannel audio has severe limitations (principally with images collapsing into one channel or speaker) that only become obvious once one hears a system with crosstalk cancellation. The first time I heard a BACCH system (incredibly to me now, in March 2015), it was clear that much of the Toole/Harman conventional wisdom had gone out the window.

Many papers and other resources such as speaker measurements can be found at https://www.princeton.edu/3D3A/

I believe, like Toole, that correction cannot fix speaker issues. Correction is best limited to below Schroeder to fix room issues.

If physics apply, BACCH‘s crosstalk removal for speakers must become less effective as the frequency increases and wavelengths shorten.

What in Toole/Harman conventional wisdom has been thrown out the window?

- Confirmation bias
- The importance of Measurements
- Blind testing

- Rich

 

[Dialectic]

I believe, like Toole, that correction cannot fix speaker issues. Correction is best limited to below Schroeder to fix room issues.

If physics apply, BACCH‘s crosstalk removal for speakers must become less effective as the frequency increases and wavelengths shorten.

What in Toole/Harman conventional wisdom has been thrown out the window?

- Confirmation bias
- The importance of Measurements
- Blind testing

- Rich

Again, no one is saying that measurements don't matter or biases don't apply. I said nothing about correcting speakers.

The disagreements between Toole and Choueiri were discussed by the men themselves in this thread: https://www.audiosciencereview.com/forum/index.php?threads/bacch4mac-pro-edition-a-report.2373/

The sorts of studies cited in the Toole book are helpful but rather primitive compared to what is being done at Princeton. I will upset some on ASR saying this, but Revel speakers with subs, room correction, and high SINAD amplification are all fine but have a low ceiling compared to what is possible with BACCH.

 

[onion]

If a user runs a correction product until they like the predictive charts and sound, that is wonderful. It is however, not the pinnacle of science.
Their results are subjectively better, just as mine are when I compare results the non-corrected sound.

The results are the results. The magnitude of XTC does depend on room and speaker factors, but if you have your room, listening position, speakers and acoustic treatment all sorted out, there's no point running BACCH 'until you like the predictive charts and sound'. There is also a bypass button in the software that you (or a friend if you are blind-testing) can easily toggle. The difference between filter and no-filter is really really obvious.

Listening through BACCH is much less fatiguing than regular listening. I think that in the latter case, the brain hears stereo sounds emanating from a plane bound by the speakers. This is not natural compared to a 3d spatial audio system, where each source of sound has its own position in 3d space.

You can use the measurements generated by BACCH to identify the source of problematic reflections (same as many other computer audio programs) - dealing with these will help improve 3d spatial audio performance.

The magnitude of XTC measured in dB correlates with 3d spatial audio performance. At 3dB XTC, you will not be able to hear a sound, recorded right next to the mic, as though it emanates right next to your ear. At 15dB XTC, you will hear this.

 

[ARQuint]

The results are the results. The magnitude of XTC does depend on room and speaker factors, but if you have your room, listening position, speakers and acoustic treatment all sorted out, there's no point running BACCH 'until you like the predictive charts and sound'. There is also a bypass button in the software that you (or a friend if you are blind-testing) can easily toggle. The difference between filter and no-filter is really really obvious.

And how! What's kind of surprising is what a difference the filter can make with non-purist (to put it mildly) studio recordings of popular music, what Dr. C refers to as "concocted." Not all, by any means, but many.

 

[lanzarote]

This is a video review of a crosstalk processor.

Andrew Quint Previews the Unique BACCH-SP Stereo Purifier

You can read Andrew's full review of the BACCH-SP in our December issue, now available in print and digital. Andrew Quint previews the unusual, but no

www.theabsolutesound.com

It is very slow moving; this is a product with an analog input version and digital version priced at $23,800 and $19,800.
The product comes with an iPad, camera, and ear mounted microphones and takes measurements in the listening position and two others approximately two feet apart.
The claim is to eliminate crosstalk with a filter providing greater:

• Envelopment
• Proximity and Depth
• Spatial Extension
• Resolution

This is backed up by actual measurements, just kidding.

You might well guess the target audience.
Andrew is in no danger of going viral

-Rich

Don't just say, "actual measurements." Measurements of what and (most importantly) to what end? It is bothersome when these parameters are not specified. Measurements are only a means to an end.

Here is the founder's bio (he a professor at Princeton in Acoustics among other things engineering). The bio makes reference to his/his team's "many publications and patents including a new technique for producing tonally pure 3D sound from two loudspeakers": https://mae.princeton.edu/people/faculty/choueiri

It seems safe to say that the device was measured to achieve the intended effects and subjective listening reviews (many of which hail the effects of this device as knock-you-over-the-head obvious and also representing a revolution in 2-channel audio) seem to confirm the effects are as described. What's the problem?

 

[Justdafactsmaam]

I’ve heard the Bacch SP playing through a set of Kef LS50, and it was remarkable. How do you measure it? I’m not sure. I can tell you that binaural recordings were spooky real, with sounds moving around very clearly in 3D space and moving above the ceiling and below the floor, with pretty much 360 degree envelopment. As wild as the claims may seem, I do feel like it delivers on them. Is it worth the price? Not to me. I’d gladly run it if I had it though.

It’s easy to measure. The program does it for you. It literally displays the XTC (cross talk cancellation) for each channel across the audible frequency domain in dbs.

 

[Justdafactsmaam]

I still haven't heard anything that is more impressive than BACCH, and that's why I use it in my system, despite the added complexity. It has ruined conventional stereo listening for me.

It's very much a science-oriented product...

I agree. IMO the biggest breakthrough in audio since the invention of stereo.

 

[Justdafactsmaam]

Again, no one is saying that measurements don't matter or biases don't apply. I said nothing about correcting speakers.

The disagreements between Toole and Choueiri were discussed by the men themselves in this thread: https://www.audiosciencereview.com/forum/index.php?threads/bacch4mac-pro-edition-a-report.2373/

The sorts of studies cited in the Toole book are helpful but rather primitive compared to what is being done at Princeton. I will upset some on ASR saying this, but Revel speakers with subs, room correction, and high SINAD amplification are all fine but have a low ceiling compared to what is possible with BACCH.

The BACCH is a game changer

 

[Justdafactsmaam]

I believe, like Toole, that correction cannot fix speaker issues. Correction is best limited to below Schroeder to fix room issues.

If physics apply, BACCH‘s crosstalk removal for speakers must become less effective as the frequency increases and wavelengths shorten.

What in Toole/Harman conventional wisdom has been thrown out the window?

- Confirmation bias
- The importance of Measurements
- Blind testing

- Rich

The BACCH SP actually becomes more effective as the frequency goes up. Something that is easily seen on n the XTC measurements. No doubt the head tracking and real time adjustments tackle the problem with shorter wavelengths.

What “conventional wisdom” has been thrown out the window?
1. The value of early reflections or any sound added by the room.
2. The limitations of conveying accurate spatial cues in two channel playback.
3. The importance of flat frequency response in loud speakers
4. The value of smooth off axis frequency response.
5. The ideal acoustics of a listening room

 

[lanzarote]

The BACCH SP actually becomes more effective as the frequency goes up. Something that is easily seen on n the XTC measurements. No doubt the head tracking and real time adjustments tackle the problem with shorter wavelengths.

What “conventional wisdom” has been thrown out the window?
1. The value of early reflections or any sound added by the room.
2. The limitations of conveying accurate spatial cues in two channel playback.
3. The importance of flat frequency response in loud speakers
4. The value of smooth off axis frequency response.
5. The ideal acoustics of a listening room

Agree with your implication in point 2.: Fidelity to the source (aka "accuracy") and not the opposite is what the BACCH aspires to and arguably achieves.

 

[Justdafactsmaam]

Agree with your implication in point 2.: Fidelity to the source (aka "accuracy") and not the opposite is what the BACCH aspires to and arguably achieves.

Indeed it does and that accuracy can literally be tested in room. The microphones allow you to record in the listening space and directly A/B the playback to the live recording. The spatial accuracy is essentially at an end game level if the speakers and room are up to the task. Of course my other points are the factors that determine whether or not the system is up to the task to make the most of the BACCH SP

 

[lanzarote]

Indeed it does and that accuracy can literally be tested in room. The microphones allow you to record in the listening space and directly A/B the playback to the live recording. The spatial accuracy is essentially at an end game level if the speakers and room are up to the task. Of course my other points are the factors that determine whether or not the system is up to the task to make the most of the BACCH SP

Interesting! Are you an owner of the SP?

 

[Justdafactsmaam]

Interesting! Are you an owner of the SP?

Yes