Andrew Quint Reviews the Unique BACCH-SP Stereo Purifier

[Gwreck]

I have a pair of Polk L800's and just Demo'd the BACCH-SP Appliance at Axpona 2024. I spent most of my time in that room. The L800's had a wider sound stage which is likely because they are projecting sound outward AND because I have to toe-in the L800's a bit because I have them farther apart (7'). The BACCH-SP was more immersive and had head tracking.

However, The BACCH-SP set up was

• speakers were closer together than my L800's 5' vs 7'
• speakers were closer to the listening position 4' vs 8'
• I'm sure he was using very directional speakers where as I'm unsure of the directionality of the L800's
• His room was untreated and small, my room is treated fairly well
  • he very modestly "treated" the hotel room side walls (like 2" absorbers or less) vs I do not treat my side walls;
  • However, I have 16 2'x2' 4" absorbers on my back wall
  • His seats had space behind them vs I'm close to the wall
  • His seats had no headrest, mine have a head rest

XTC is fickle and worth every inconvenience but requires a lot of experimentation which I've found very rewarding for this hobby.

I tried the uBACCH VST version and was not able to make it sound better or even very effective but perhaps I was listening for the wrong things. I also had someone convolve a track and gave him dimensions and it did not work well. I'm left to assume that the VST is simply not as good as BACCH4MAC/BACCH-SP or my room is not as good for BACCH4MAC/BACCH-SP.

Problem with experimenting is that I'd have to buy and set up a Mac Mini plus buy $1000 in software OR if I really do need the upgrade for measurements (which I like the idea of measuring XTC, I haven't figured out how to do that in REW) then I'm looking at a $740 restock fee if it doesn't work as well.

I'm a home theater guy and fitting that into a home theater chain would be difficult. The BACCH-SP (despite being out of my budget) has estimated 30ms of latency (per Edgars guess) which would be after my AVR meaning it would tear up the distances and perhaps not work at all for video syncing...

So again, I loved the BACCH set up at Axpona and I think I liked it better than my L800's but I like the L800's better in my room and they fit within the home theater set up vs the one uBACCH VST that I've tried.

I plan on giving BACCH another go because the immersion was better.

Does anyone know those whisper and counting tracks he uses for demo's? I can't find them and I want to test them out. Yosi Horikawa's songs "Fluid" and "Timbres" were a revelation on his set up.

If you look up “Dr Chesky” there are several albums where the tracks come from. I have always wanted to hear a pair of LS800’s and also compare them to BACCH. (If you live in the Kansas City area I’d be will to bring my BACCH setup over.)

 

[tjcinnamon]

If you look up “Dr Chesky” there are several albums where the tracks come from. I have always wanted to hear a pair of LS800’s and also compare them to BACCH. (If you live in the Kansas City area I’d be will to bring my BACCH setup over.)

Dang! I'm in Wisconsin! If you're ever in the area then hit me up. I don't have an L800 traditional setup (i.e. close together) but they definitely work!

 

[Gwreck]

Dang! I'm in Wisconsin! If you're ever in the area then hit me up. I don't have an L800 traditional setup (i.e. close together) but they definitely work!

Certainly. Maybe I’ll trick my family into going to the dells for vacation. The L800’s are really great looking speakers. I remember seeing the original SDA’s as a teenager and thinking that they looked awesome like a Marshall 4x12.

My thought of how to compare BACCH vs the ls800 SDA would be to disconnect the SDA array when running BACCH. (I don’t own the speakers so I assume that would work)

 

[tjcinnamon]

If you look up “Dr Chesky” there are several albums where the tracks come from. I have always wanted to hear a pair of LS800’s and also compare them to BACCH. (If you live in the Kansas City area I’d be will to bring my BACCH setup over.)

Just checked some tracks.

L800's: Puts the sound about 8' outside each speaker, so about a 23' sound stage. But I did not get the whisper effect, there was nothing next to my head. The seat being close to my head and position to the back wall could reduce this effect.
BACCH-SP at Axpona: Did not go out as far, pretty much to the boundary of the room. BUT the immersion toward me, the listener, was much much greater.

Plus there's a huge variable about the directionality of the speakers.

There's a very large difference between the two.

I'm aiming to get this working for a home theater setup. I think step one is proving that the sense of immersion is better than the extension of the sound stage. My guess is I'd like the immersion better with surround sound because my upmixed surrounds could cover outside the plane; the traditional XTC will create the bubble.

Ugh! Decisions decisions!

Here's a good thread and some options that I looked at to home roll something to implement @Tim Link crosstalk cancellation methods:

Analog Option

Stereo Crosstalk Elimination (reduction) Par Excellence!

But if I EQ before I sum the signals won’t the L-R and R-L not work properly? Basically, something that should only end up in the center would end up slightly left or right as well. Because LR would no longer be the same after EQing only one of them It depends. If you are EQing for subtle...

www.audiosciencereview.com

Digital vs Analog Options

Stereo Crosstalk Elimination (reduction) Par Excellence!

But if I EQ before I sum the signals won’t the L-R and R-L not work properly? Basically, something that should only end up in the center would end up slightly left or right as well. Because LR would no longer be the same after EQing only one of them It depends. If you are EQing for subtle...

www.audiosciencereview.com

 

[tjcinnamon]

I'm sure you have a DAW of some sort and a computer you can connect to your sound system, so why not download the simple uBACCH VST plugin and try it out, they have a 14-day free demo. The plugin has only one slider to set and that is the degree of the listening window and you are good to go.

I tried it out but wasn't too impressed. It worked nicely on some tracks, especially recordings made with some sort of stereo micing technique, but when it comes to panned multi-mono recordings it can go either way, some work well while others will sound almost broken. What was clear to me was the music should be done with the BACCH filter in mind to make sure the mix would not fall apart.

One of the worst examples I heard was one of those old ping-pong stereo recordings with The Beatles, you know one of those where all the instruments are located in the left channel and the singer is located in the right channel. With normal playback a recording like that doesn't sound too awful, but with the BACCH filter applied it no longer just sounds like instruments come from the left side of the room and the singer from the right side of the room, the channels are now completely detached and isolated from each other and it sounds exactly as wrong as such recording sounds in a pair of headphones.
I know it's an extreme example, but even in modern multi-mono mixes it's not uncommon that individual instruments are hard-panned all the way out to either the left or the right side, and those individual sound elements will suffer the same way as in the Beatles example and when that happens it sounds very unnatural with the BACCH filter.

But I don't want to sound too negative. If your main listening habits are natural stereo recordings based on inter-channel time difference and natural room acoustics, the BACCH filter can sound amazing and can give you that extra sensation of envelopment.

So you were able to compare uBACCH VST vs BACCH4MAC?

 

[goat76]

So you were able to compare uBACCH VST vs BACCH4MAC?

No, I have not had the opportunity to try BACCH4MAC in my system, only the uBACCH as I have a Windows-based computer. I asked some BACCH users in another thread if there was a significant sound difference between the full-scale program for Mac and uBACCH as long as no head tracking was used and if I sit still right at the sweet spot, and according to them it should sound pretty much the same.

 

[Justdafactsmaam]

No, I have not had the opportunity to try BACCH4MAC in my system, only the uBACCH as I have a Windows-based computer. I asked some BACCH users in another thread if there was a significant sound difference between the full-scale program for Mac and uBACCH as long as no head tracking was used and if I sit still right at the sweet spot, and according to them it should sound pretty much the same.

Definitely not the same. Big difference between a custom filter and the stock filter

 

[tjcinnamon]

The only way I can see this working for multi user home theater is ORC combined with The BACCH-X.

I just want it to work with my LR while my AVR does the rest. I can put it after the AVR signal chain but it can add some latency and depending on how much is the X-Factor.

 

[Gwreck]

I just want it to work with my LR while my AVR does the rest. I can put it after the AVR signal chain but it can add some latency and depending on how much is the X-Factor.

I have a Dolby pHRTF but have not had the motivation to see how it works with surround content on my Xbox series X

 

[STC]

L800's: Puts the sound about 8' outside each speaker, so about a 23' sound stage. But I did not get the whisper effect, there was nothing next to my head. The seat being close to my head and position to the back wall could reduce this effect.

L800 comes with fixed values and therefore to get perfect XTC to match your HRTF, you need to moved the speakers until it matches yours.

Whispering reaching your ears is something you can play with a DAW by just send the inverted delayed signal to the other speakers. You just need a delay plugin which comes inbuilt with DAWs. I think you can do that with JRiver itself. This is known as one shot cancellation like Carver did with his Holographic Amplifier.

In reference to the colouration claim, it is just a Bogeyman. Until all the “experts/developers” put their product in one room and invite people to judge for themselves I rather make comparison by real sound from speakers with and without XTC to judge coloration . Colouration was an issue during the pre digital era but with recursive or Convolution of IR it is no longer the case. Perhaps, one is a better than the other based on measurements like Ted Denney and SR ( or was it Shunyata?).

 

[tjcinnamon]

I was able to get a greater effect using both the L800’s with uBACCH. I wasn’t able to listen to much because I only have 2 tracks I was running through a trial of JRiver.

I need to run Spotify through JRiver to actually demo the tracks.

The uBACCH experience is better this time around. I run it at 28.

I need to experiment more but this is promising.

The combination sounds better than when I “disable” (unplug) the SDA and run uBACCH on its own.

 

[STC]

I was able to get a greater effect using both the L800’s with uBACCH. I wasn’t able to listen to much because I only have 2 tracks I was running through a trial of JRiver.

I need to run Spotify through JRiver to actually demo the tracks.

The uBACCH experience is better this time around. I run it at 28.

I need to experiment more but this is promising.

The combination sounds better than when I “disable” (unplug) the SDA and run uBACCH on its own.

XTC meant to listen to conventional stereo recordings. Although, having special binaural or other recording with correct ILD and ITD can enhance the XTC effect, it is not the intent of XTC to listen only to some special recordings. Not all artists can have access to Chesky to mastered to make ch their chosen XTC.

 

[tjcinnamon]

XTC meant to listen to conventional stereo recordings. Although, having special binaural or other recording with correct ILD and ITD can enhance the XTC effect, it is not the intent of XTC to listen only to some special recordings. Not all artists can have access to Chesky to mastered to make ch their chosen XTC.

I have tracks like Radiohead, Tipper, Mr Bill, 13 and God, etc….

All standard 2 channel stuff. The only MP3’s I have a Hotel California and Yosi Horikawa’s Bubbles

So my sample size is very small for testing until I can stream my playlists

 

[onion]

Better in what sense? Subjectively sounds better, or measures better? I have yet to see any objective reviews of BACCH, including measurements, workflow, what it corrects, etc. I would love to see one. Would you like to start a thread?

Hi Keith

Better subjectively and objectively. First picture below shows GLM measurement pre-ORC freq response at an averaged listening spot. BACCH shows the pre-filter measured response (which is in-ear and slightly different to the averaged GLM listening spot), and also the measured post-ORC-filter response. It's actually easy to compare before and after subjectively too, and also blindly (if you have another person in the room who controls the software) - as it's a simple case of toggling the ORC filter on and off. There is an option to level-match pre- and post-ORC too.

As far as multiple instances of ORC at the same time in the same room for multiple people, I thought this required some sort of phase array speaker system that Theoretica have a prototype of. This would be ideal for home cinema which I'm guessing is more of a social experience. BACCH is pretty much a single listener device at the moment, so not for every use case currently.

 

[tjcinnamon]

Hi Keith

Better subjectively and objectively. First picture below shows GLM measurement pre-ORC freq response at an averaged listening spot. BACCH shows the pre-filter measured response (which is in-ear and slightly different to the averaged GLM listening spot), and also the measured post-ORC-filter response. It's actually easy to compare before and after subjectively too, and also blindly (if you have another person in the room who controls the software) - as it's a simple case of toggling the ORC filter on and off. There is an option to level-match pre- and post-ORC too.

As far as multiple instances of ORC at the same time in the same room for multiple people, I thought this required some sort of phase array speaker system that Theoretica have a prototype of. This would be ideal for home cinema which I'm guessing is more of a social experience. BACCH is pretty much a single listener device at the moment, so not for every use case currently.

View attachment 364883View attachment 364885View attachment 364886

One could argue that all Stereo listening is a single listening device. There is only one sweet spot to get the phantom image.

Dirac presents in the user interface a couch when measuring but the guidance says really no more than 18” around the listener.

I think the difference is Dirac/audyssey/stereo you can move your head about 18” whereas this you can move it about 5”

 

[STC]

Better subjectively and objectively.

Which is better subjectively can only be determined when every developer himself makes the recording and personally setup your system so that you can listen to all the different XTC out there and judge for yourself.

 

[Justdafactsmaam]

One could argue that all Stereo listening is a single listening device. There is only one sweet spot to get the phantom image.

Dirac presents in the user interface a couch when measuring but the guidance says really no more than 18” around the listener.

I think the difference is Dirac/audyssey/stereo you can move your head about 18” whereas this you can move it about 5”

You can move your head a lot more with your he head tracking