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BACCH4Mac Pro Edition - For those considering BACCH

Zoomer

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Another way to do it that I think is interesting is to run regular stereo through your front speakers and then have another set of speakers, time delayed and attenuated near each of your ears to eliminate crosstalk.
Sounds interesting, especially as I have a pair of spare mains standing around. Any references to how this works and setup?
 

Tim Link

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Sounds interesting, especially as I have a pair of spare mains standing around. Any references to how this works and setup?
The way I did it was by using four speakers powered by a 5.1 surround receiver and setting the surround mode to all channel stereo. Then I set the distances on the speakers and adjusted the levels by ear. I had small speakers on a shelf behind my head to put them near my ears - within about 4 inches, so it's pretty close. You don't want the sound from those speakers excessively cross talking to your ears either so they need to be pretty close to each ear to prevent that. The front speakers are wired up normally but the rear speakers are wired up out of phase and left/right reversed. When the time delay and level are adjusted right you hear the sound stage get really wide and deep. Another variation on this that I tried just for fun was to combine left and right channels into a single channel and run it from a single speaker directly in front of me. I figured it should still work as the crosstalk elimination speakers would still be removing the same information from each ear. It works, but not as well as having two front speakers for whatever reasons.
 

adLuke

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Thank you @Tim Link for your reply.
I will try and find out about soundpimp and Mini DSP.
The most interesting would be to try with the loudspeakers set the way you mentioned.
Is there somewhere I can read how to do that well and how it works? I would really appreciate help on that as I am really keen to learn about it.
Also, have you had the chance to listen to Bacch-powered hifi? how does ambiophonics compare?
Thanks in advance
 

Tim Link

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@adLuke
I have not read about the near field crosstalk elimination method I mentioned. I thought I invented it but then talked with the guy who runs Soundpimp and found out that he had experimented with that method too. I've had no chance yet to hear the Bacch system. I've never heard the Ambiophonics in it's entirety either, with ambience channels and all. I've just tried various crosstalk elimination methods. The best I've heard so far has been from using a physical dividing wall.
Back to the near field crosstalk elimination speakers, I haven't experimented with it recently but I've thought a good way to do it might be to use a headrest of some kind as a divider behind your head, with speakers on either side of it behind your ears, the baffles of those speakers angled at 45 degrees so they don't bounce the main speaker sound back into your ears. To optimize the crosstalk the rear speakers would have to be equalized appropriately. You could do it by ear by playing various tones from one of the front speakers and then adjusting the opposite side rear speaker level at each frequency to maximize the cancelation effect. Ideally you'd only hear the signal from each speaker in the appropriate ear, with apparent silence in the other ear when the cancellation is maximized.
 

adLuke

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@adLuke
I have not read about the near field crosstalk elimination method I mentioned. I thought I invented it but then talked with the guy who runs Soundpimp and found out that he had experimented with that method too. I've had no chance yet to hear the Bacch system. I've never heard the Ambiophonics in it's entirety either, with ambience channels and all. I've just tried various crosstalk elimination methods. The best I've heard so far has been from using a physical dividing wall.
Back to the near field crosstalk elimination speakers, I haven't experimented with it recently but I've thought a good way to do it might be to use a headrest of some kind as a divider behind your head, with speakers on either side of it behind your ears, the baffles of those speakers angled at 45 degrees so they don't bounce the main speaker sound back into your ears. To optimize the crosstalk the rear speakers would have to be equalized appropriately. You could do it by ear by playing various tones from one of the front speakers and then adjusting the opposite side rear speaker level at each frequency to maximize the cancelation effect. Ideally you'd only hear the signal from each speaker in the appropriate ear, with apparent silence in the other ear when the cancellation is maximized.
Oh I get it.
Thanks a lot for the explanation. I will try to experiment sometime and follow your suggestions.
Meanwhile, I will still try to hunt down some ambiophonics filters :cool:
Thanks a lot for your help.
 

daclogic

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A question for users, like @Dialectic @onion and of course @Theoretica Appl. Physics (and others I've missed)​

(But first a thank you for sharing your knowledge on this. I only came across this in the last week and so far have read for hours utterly intrigued. And thanks also for your music list @Dialectic, which is still being mined.)
I have read that in Bacch4Mac you can make three (or seven) bins for the software. I had assumed that could be three (or seven, whichever is correct) iterations where any factor could be changed – for example, if three bins is the limit, three different listening positions for one person in one room; or three rooms, three different sets of speakers, one profile each for one person; or three different sets of speakers for one person in one room. Was my assumption mistaken? I ask because earlier entries suggest this is the case and I'd love to know. Might not affect my intention to buy, but would be nice to know.
If that is the case, is there a way of 'parking' a measurement, storing it somewhere, and reimporting it later? If not, is such a thing feasible?
Thanks in advance
(I've still got stacks of questions, And more reading to do.)
 

kthulhutu

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A question for users, like @Dialectic @onion and of course @Theoretica Appl. Physics (and others I've missed)​

(But first a thank you for sharing your knowledge on this. I only came across this in the last week and so far have read for hours utterly intrigued. And thanks also for your music list @Dialectic, which is still being mined.)
I have read that in Bacch4Mac you can make three (or seven) bins for the software. I had assumed that could be three (or seven, whichever is correct) iterations where any factor could be changed – for example, if three bins is the limit, three different listening positions for one person in one room; or three rooms, three different sets of speakers, one profile each for one person; or three different sets of speakers for one person in one room. Was my assumption mistaken? I ask because earlier entries suggest this is the case and I'd love to know. Might not affect my intention to buy, but would be nice to know.
If that is the case, is there a way of 'parking' a measurement, storing it somewhere, and reimporting it later? If not, is such a thing feasible?
Thanks in advance
(I've still got stacks of questions, And more reading to do.)
I have three bins in the audiophile edition. You can load each bin with u-bacch, h-bacch or head tracking + h-bacch filters. I think you can store a separate head-tracked and non-head tracked filter in each one. I don't think there's a built-in way to export individual filter measurements, but you can export the entire workspace to a file which should achieve the same thing.
 

daclogic

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I have three bins in the audiophile edition. You can load each bin with u-bacch, h-bacch or head tracking + h-bacch filters. I think you can store a separate head-tracked and non-head tracked filter in each one. I don't think there's a built-in way to export individual filter measurements, but you can export the entire workspace to a file which should achieve the same thing.
Hey, thanks for your answer. Great to know.
 

Theoretica Appl. Physics

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It is mind-blowing. There is a big caveat to wider adoption - it's really only designed for one person to listen to at a time. I believe they are researching new types of speakers to see if they can deliver XTC at multiple positions in the room, but this is some way off.
While indeed BACCH is optimized for a single listener, with the head tracking feature available in the BACCH4Mac Audiophile version (and above) the sweet spot is not fixed and moves with the listener. (Also, people lining up behind the main listener would get a good 3D image, and people not in the sweet spot would hear regular stereo.)

(p.s. Regarding multiple sweet spots: we have finished developing the technology (called BACCH-X) and it is now working perfectly. However, it requires a phased array (which has a minimum of 8 transducers) and is not compatible with two-speaker systems. We plan on adding a BACCH-X module in a future version of BACCH-dSP that allows adventurous and experimentally-minded users to line up an array of regular speakers to create a phased array that can produce multiple sweet spot. Incidentally, with BACCH-X each sweet spot is steered via head tracking to follow the head of the intended listener.)

Regards,
Adam at Theoretica
 
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Theoretica Appl. Physics

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I've had minimal problems using the lowest end M1 Mac mini (8Gb). The only issue is that the machine is a Roon core so is left on all the time - if Bacch4Mac is also left running all the time, this can cause a memory error message. The simple fix is to quit Bacch4Mac after finishing up a listening session. For me, this minor hassle is worth putting up with compared to using an Intel Mac mini because of the heat and noise reduction.

Will be interesting to learn if further advances in the software will require upgraded hardware - for me there was a subjective jump in performance going to version 10 and I could imagine that further improvements in processing might yield even better results.
This issue was a memory leak and was fixed in a previous version of BACCH-dSP. The latest version 11.4.1 does not have a memory leak on M1 or other Macs.

Regards,
Adam at Theoretica
 

Theoretica Appl. Physics

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3) I had hoped that the Bacch algorithm was sophisticated enough that it could be “focused” on various listening spots. In my case, the center spot on the couch is reserved for dedicated serious listening, but I spend most of my evenings (and listening time) lounging on the couch when listening to music while reading, etc., with my head offset several feet outside of the ideal listening window (which isn't that narrow to begin with). I was hoping that Bacch could address this, but apparently not; Bacch requires a “sweet” spot, per my friends who witnessed the demo at AXPONA.

Please see my reply to Onion above. Essentially: While indeed BACCH is optimized for a single listener, but with the head tracking feature available in the BACCH4Mac Audiophile version (and above) the sweet spot is not fixed and moves with the listener. That means you can sit anywhere on your couch and as long as you are in the field of of view of the webcam (and you have made a BACCH filter with head tracking that covers the whole couch) the head tracking will steer the 3D imaging sweet spot to exactly where you are sitting.

An ideal implementation for me would be for Bacch to be available as a plugin that could be accessed via jRiver Media Center's DSP menu in the Windows environment.
Since BACCH-dSP uses a lot of CPU and GPU resources (to do intensive dSP and head tracking) it is very difficult, if not impossible, to make it a plugin.
A growing number of Windows-based BACCH users use Dante to connect their PC (running and audio player, such as jRiver) to the Mac (running BACCH-dSP), which outputs the BACCH-processed audio to a USB DAC.

Adam at Theoretica.
 

Theoretica Appl. Physics

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Seems to me any competent interface would suffice, especially as that's probably a one time use and runs $1000 USD.
The audio interface is only needed to get the BACCH-Bm binaural mic signal to the Mac. Indeed, while we still recommend the RME interfaces (the BabyFace Pro FS or, in the case the BACCH-Xover module is used, the UCX II) because of their electronically well-matched and ganged Left-Right gains on the stereo mic pre, we have introduced in version 10.1 of BACCH-dSP a new mic gain calibration feature that allows perfectly matching the L-R gains using a simple procedure that relies on BACCH-dSP playing a 1 kHz sine wave played through the left speaker. This feature allows the user to use any USB audio interface that has a decent stereo mic pre (even those where the L & R gains are set manually and are thus neither ganged or well-matched). Many such USB audio interfaces are available at a cost that is lower than that of the RME interfaces.

Adam at Theoretica
 

Coolerking101

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Hate to triple-post but there's no way to delete your own posts on this forum.

So I've gotten around to trying Bacch DSP, just the intro edition with no mics or measurements.
I know I said Mac only was a deal-breaker, but Bacch support kindly and promptly suggested Dante virtual soundcard as a solution. Using this I've been able to transmit all digital input from my Windows machine through ethernet to a Mac mini with minimal latency.
Buying a whole separate machine does seem excessive, but with the difference Bacch can make it's worth it.

I'm also considering Dante as an option...but I'm not sure how this would ultimately work. I have my Mac and my PC each connected to my receiver via HDMI. It's not possible to select audio from one source (mac) and video from another (PC) when using HDMI. So how do you view your PC to select songs while playing audio from your Mac? Do you use an iPad or some other external device to select music from your PC so that your DAC/receiver only receives a/v information from your Mac?
 

phoenixdogfan

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As long as we have a person from Theoretica following this thread, I have a question regarding the Pro Edition of Bacch4Mac.

Adam, I see the Pro Edition appears to have three features the Audiophile+ and Audiophile editions lack. Specifically, I would like to know about what the Bacch 3DM, and Bacch-hoa. Who and what are they for? Would an ordinary audiophile who simply wants to use Bacch to play back music and cinema have any use for them? It looks to me like they could be of use in downmixing Atmos program material to a binaural simulation in real time to play over speakers or headphones. Is this correct, and does it work, like say a Smyth A16 which provides this for headphones? And does the B4M extend this capability to two channel speaker systems as well? Would this work, for example, if I wanted to play a Netflix Atmos movie streamed on my Mac Mini, and have my two channel set up realistically emulate 24 channel Atmos? Could Bacch even get the Atmos LPCM stream from the MacMini? And would it not need LPCM because, I'm sure, Bacch doesn't come with an Atmos license?

Or am I just misreading this, and are these features rather designed to be useful to content creators, more so than regular audiophiles?
 
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kthulhutu

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I'm also considering Dante as an option...but I'm not sure how this would ultimately work. I have my Mac and my PC each connected to my receiver via HDMI. It's not possible to select audio from one source (mac) and video from another (PC) when using HDMI. So how do you view your PC to select songs while playing audio from your Mac? Do you use an iPad or some other external device to select music from your PC so that your DAC/receiver only receives a/v information from your Mac?

My setup is specifically a PC centric desktop one, so I simply route all my Windows audio through to my Mac which acts as a slave machine and I don't use it for any audio playback. For viewing the Mac screen I have it plugged into my monitor's second input and I also use an RDP application from my Windows machine to remote in without having to switch around my peripherals.
 

Coolerking101

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My setup is specifically a PC centric desktop one, so I simply route all my Windows audio through to my Mac which acts as a slave machine and I don't use it for any audio playback. For viewing the Mac screen I have it plugged into my monitor's second input and I also use an RDP application from my Windows machine to remote in without having to switch around my peripherals.
Ah. This makes sense. I don't have a dedicated audio area. My basement HT is also my audio area, so the TV is my "monitor" for everything. I suspect I'm going to be stuck living with a Mac moving forward. So glad I have a supercharged PC NUC that I've spent countless hours perfecting into a quality 2ch and Multichannel music machine. SMH.
 

phoenixdogfan

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Ah. This makes sense. I don't have a dedicated audio area. My basement HT is also my audio area, so the TV is my "monitor" for everything. I suspect I'm going to be stuck living with a Mac moving forward. So glad I have a supercharged PC NUC that I've spent countless hours perfecting into a quality 2ch and Multichannel music machine. SMH.
Why can't the Mac be that quality 2ch and multichannel music and AV server? What does an Intel Nuc do, that an M1 Mac Mini can't? I've heard of set up where people do what you are doing, and I'm really puzzled why they do that? Why not just use the Mac for everything?
 

Coolerking101

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Why can't the Mac be that quality 2ch and multichannel music and AV server? What does an Intel Nuc do, that an M1 Mac Mini can't? I've heard of set up where people do what you are doing, and I'm really puzzled why they do that? Why not just use the Mac for everything?
You're absolutely right. Anything a NUC can do a M1 Mac can do. I, however, already have a kick-ass NUC and am using a Mac from 2014 that is painfully slow and clearly less than ideal for these purposes. So my issue is really about having to spend another $600+ for an M1 Mac after having already invested in a NUC (nevermind having spent countless hours fiddling with my library).
 

phoenixdogfan

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You're absolutely right. Anything a NUC can do a M1 Mac can do. I, however, already have a kick-ass NUC and am using a Mac from 2014 that is painfully slow and clearly less than ideal for these purposes. So my issue is really about having to spend another $600+ for an M1 Mac after having already invested in a NUC (nevermind having spent countless hours fiddling with my library).
Ok, thanks. I just have seen a couple of instances where people are using both machines, and I was a little bit puzzled. Thanks for clearing it up. My takeaway at this point is that an M1 Mac Mini can do just about anything as a server that an AV enthusiast/audiophile could reasonably need. Considering it costs only around $600 and is compact and ultra quiet, that's extremely good to know.
 

Theoretica Appl. Physics

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As long as we have a person from Theoretica following this thread, I have a question regarding the Pro Edition of Bacch4Mac.

Adam, I see the Pro Edition appears to have three features the Audiophile+ and Audiophile editions lack. Specifically, I would like to know about what the Bacch 3DM, and Bacch-hoa. Who and what are they for? Would an ordinary audiophile who simply wants to use Bacch to play back music and cinema have any use for them? It looks to me like they could be of use in downmixing Atmos program material to a binaural simulation in real time to play over speakers or headphones. Is this correct, and does it work, like say a Smyth A16 which provides this for headphones? And does the B4M extend this capability to two channel speaker systems as well? Would this work, for example, if I wanted to play a Netflix Atmos movie streamed on my Mac Mini, and have my two channel set up realistically emulate 24 channel Atmos? Could Bacch even get the Atmos LPCM stream from the MacMini? And would it not need LPCM because, I'm sure, Bacch doesn't come with an Atmos license?

Or am I just misreading this, and are these features rather designed to be useful to content creators, more so than regular audiophiles?

Both the hoa and 3dm modules, which as you stated correctly are only available in the Pro Edition of BACCH4Mac, are described on the BACCH-dSP webpage. Basically, the hoa module features many advanced technologies for higher order ambisonics (HOA) to binaural downmixing, sound field navigation, beamforming, head-tracked beam steering, stereo microphone emulation, etc. that are not (yet) of direct relevance to audiophiles. The BACCH-hoa mdoule is mostly used by spatial audio professionals, recording engineers, content creators and researchers. Most functions in the BACCH-hoa module require the use of an HOA mic, such as the 32-capsule Eigenmike (or the forthcoming 64-capsule version), which is quite expensive.

The 3dm (3D Mixer) module can indeed be used by audiophiles (who like surround sound) to emulate a multi-speaker surround sound system over a pair of speakers. The 3dm module requires discrete (i.e. decoded) multi-channels on separate buses (i.e. internal channels) that are then represented as virtual sound sources positioned in 3D space, using the 3dm module’s GUI, to be at the virtual locations of the corresponding speakers of a surround sound speaker configuration (e.g. Dolby 5.1, 7.1 and Atmos). The BACCH-3dm module then produces a binaural downmix (using either a generic pre-loaded HRTF, or the individual HRTF of the listener measured a priori in an anechoic chamber) and sends the resulting 2-channel signal to the output module of BACCH-dSP where it is filtered by a BACCH filter designed for the particular speakers used and sent out to the outboard stereo DAC to provide an emulation of multi-speaker surround system via only two speakers.

The Mac OS does not presently allow access to the Dolby-decoded N discrete channels so these must ne decoded by an outboard Dolby decoder (e.g. a receiver or an HDMI audio extractor) and sent to the Mac as N discrete PCM signals. We have recently built such a system for emulating 5.1 surround playback through two speakers at the request of a well-known audio critic who is finishing an extensive review of the BACCH-SP (Theoretica’s standalone processor) for a leading audio magazine, to be published later this year. The system takes the HDMI signal from a 5.1 DVD or SACD (file or disc) player into a Vanity Pro HDMI extractor that decodes the DSD audio signal (or Dolby coded surround from a DVD source) into 6 PCM signals, cleans the phase noise inherent in HDMI audio, thus greatly reducing the jitter, then sends the 6-channel PCM audio through AES/EBU to a Lynx AES16e-SRC PCI Expresscard connected to a Mac mini running the BACCH-dSP application. There, the BACCH-3dm module, where the virtual sources are positioned by the GUI in 3D space following the standard prescription of the ITU 5.1 speaker configuration, produces a downmix of the 6-channel audio to a 2-channel binaural signal using one of the 10 pre-loaded HRTFs in the BACCH-dSP HRTF library (or the HRTF of the intended listener, if that measured HRTF is available). The binaural downmix is then processed by a BACCH filter in the output module of BACCH-dSP and the stereo signal is finally sent to the outboard DAC for playback through two speakers. (In the particular case of the audio critic reviewing the BACCH-SP the final processing through the BACCH filter was done on the BACCH-SP, connected via USB to the Mac mini, instead of the BACCH-dSP application on the Mac mini.)

To enhance the accuracy of the 5.1 surround speakers emulation, we measured the individual HRTF of the audio critic in the anechoic chamber of Princeton University’s 3D3A Laboratory, and used that HRTF on BACCH-3dm to produce the downmixed binaural signals.)

Since the BACCH-3dm mixer allows instantiating up to 20 virtual sources, a similar approach can be used to emulate an Atmos system if an Atmos decoder is available.

We plan to eventually offer such pre-configured 5.1 (and 7.1) emulation system (including the Vanity Pro HDMI extractor and the Lynx AES16e-SRC PCI Express) as an option for surround sound enthusisats who wish to emulate surround sound playback through the BACCH-SP processor or the BACCH-dSP application of BACCH4Mac Pro.

Regards,
Adam @ Theoretica
 
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