BACCH Stereo Purifier
Stereo playback -- is it really a solved issue? Although we can always enjoy making adjustments and variations in speakers, setup, equipment, room treatments, and accessories, there aren't supposed to be any genuine innovations left on the audio pioneering trail.
As something of an expert in audio, I thought my understanding of stereo playback was complete, but nay, there it was: obvious evidence that standard stereo conceals significant elements of the listening experience. I was hearing those elements unmasked by BACCH SP.
There are already three conventional approaches to recovering some of the missing experience, namely multi-channel playback, omnidirectional stereo speakers, and dipole stereo speakers. They do help quite a bit with immersion issues, but pale in comparison to the revelation of using BACCH. Whereas those three approaches compensate by adding extra sound, BACCH exposes the hidden musical experience present but locked away in your stereo recordings.
It does this by reducing playback sound that's not on the recording, and revealing sound that had been masked by standard stereo playback.
About that cartoon, if you want to eliminate the possibility of ever hearing that particular insult, a BACCH SP system will take care of the issue.
A BACCH system places you in a pure musical space, with no sense of speakers or walls, and does so without introducing distortion or sonic artifacts.
You may be familiar with processors that widen the soundstage, but BACCH is a first-of-its-kind breakthrough, and this is not hype. Reviewers and experts in home and professional audio agree and sing its praises. For some of the reviews, please see this page on the Theoretica Applied Physics web site.
Here's a discussion of the issues with standard stereo playback, and how BACCH solves them. These issues are not widely known, so you might be in for a surprise or two.
1) The least subtle issue is that a substantial amount of the direct sound from your right speaker finds its way around your head and into your left ear, and of course vice versa. This is called crosstalk. This is not caused by sound that bounces off the walls, but sound that actually diffracts around your head. This part of the sound doesn't care that your head is in the way.
Why is that a problem? In real life, each sound source is produced by a single instrument. By contrast, in standard stereo, two speakers are simulating an array of instruments. Crosstalk causes your ears to hear both speakers at once, blurring the spatial cues that let your brain place sounds precisely.
BACCH eliminates that interference, so each ear hears what it’s supposed to, just as in real life. The result isn’t the “inside your head” effect of headphones, but a spacious, three-dimensional soundstage that opens up in front of and indeed all around you, where voices and instruments appear real and detached from the speakers.
Now, it's pretty obvious that a live performance is wider than the space between a pair of speakers, plus there's the sound of the performance hall all around you. When listening at home, however, we accept that a playback image mostly hangs between the speakers, and is augmented by wall splash to add realism. This wall splash is critical to the standard way of hearing stereo. Without it, recordings sound dry, and the sound is completely pinned between the speakers.
In addition, because of this normally critical wall splash, room ambiance covers up the recorded ambiance.
Another effect of standard stereo delivery is that the sense of height and depth is limited to what the speaker design can deliver.
When crosstalk has been markedly reduced, however, you'll hear the actual image fully in all three dimensions. If you've got a room with treated first refection points, and sufficiently directive speakers, this will even include the area behind your seat. This is because, in addition to a fully realized image, reduced crosstalk also lets the sound of the performance space better compete with your local room ambiance, allowing you to experience the original performance space.
When your eyes are closed, especially while a two-microphone or binaural recording is being played back, the sensation is very close to being where the microphones were.
If you're familiar with other systems that purport to serve this function, it's critical to understand that BACCH introduces absolutely no signal processing artifacts. The sound remains pure, unadulterated by resonances, distortions, tonality shifts, swishing sounds, or any other artifact.
To sum up this point, by cancelling crosstalk, the BACCH system unlocks the hidden glory in your stereo recordings, which is thrilling to me, and was mind bending the first time I heard it, and still is most of the time. Playback sounds as if your room has no speakers. This transformation is a key element of the term stereo purification, which is what the SP in BACCH-SP stands for.
2) This next point has to do with further reducing the effect of your room along with any potential issues with speaker placement, regardless of room treatment.
With conventional stereo, your room alters the sound substantially. Furthermore, standard stereo depends on having a certain amount of local ambiance. Unfortunately, almost never does a room's reverberant and reflected sound match the venue sound on recordings, so in a sense, its presence can be considered a form of distortion.
One of the hidden treasures on your recordings is the undiluted ambiance of the room or hall where the recording was made. BACCH's unique form of ambiance recovery completes the task of making your room disappear, thus transporting you to the original performance space. It's called ORC, for Optimal Room Correction.
The ORC software module is new as of 2024. It almost completely cancels your room's influence on the sound. It does this by equalizing the direct and indirect sound separately, and does so in both the time and frequency domains. This makes it unique in the world of automated or semi-automated room correction, and the result is uniquely satisfying.
You'll experience a sense that you are hearing for the first time just how amazingly beautiful and convincing recorded music can be.
3) There's a disconnect between how microphones work vs. how ears work. This accounts for a good bit of how recorded music can usually be easily identified as being played back vs. live.
The functional difference is that the tonal and loudness response of our ears depends on the direction that the sound is coming from. A microphone, however, is equally sensitive to the tonality of sound coming from all directions, and in some cases, also equally sensitive to the loudness. This causes an inherent brightness or sometimes stridency in two-channel recordings where the engineer hasn't addressed the issue, which is the usual case.
Most microphones take the sound received from the sides and rear, and make a signal that has the same tonal balance and loudness as if it were received from the front, where the performers usually are. Your ears hear things differently than that when hearing a live performance, so the sound that reaches the microphones from the side and rear walls of the performance space are reproduced in stereo differently than you'd hear them live. It's important to note that this ambient sound can be a large portion of the total sound heard live in a large hall, depending on how far you are seated from the stage.
As an aside, it's worth mentioning that binaural recordings do not have this problem, because binaural microphones receive sound similarly to our ears, and BACCH works especially well with them. Such recordings are rare in the general marketplace, but one studio that produces them exclusively is Chesky Records.
This issue can't be completely resolved for recordings made with conventional microphones, but is resolved to some extent by a second aspect of ORC, namely equalization to a psychoacoustically idealized target response curve. This goes a long way toward compensating for the ear vs. microphone disconnect. If you decide this compensation isn't for you, however, you can turn it off.
4) Lastly, all systems have anomalies of one sort or another in frequency response and phase coherence, mainly from the speakers and their setup, but also potentially from other items in the signal chain. You may hear this as a tendency for your system to sound better on certain types of music, or to only come alive above a certain loudness, or the image seems recessed or forward, etc.
In addition to optimally implementing room correction, ORC will correct most system response anomalies. Until you hear it for yourself, it can be hard to believe how transformative this enhancement can be. Of course, you may prefer your system's tonality as it is, in which case you can just turn off that part of ORC.
Conclusion
BACCH can be integrated into practically any stereo playback system, whether digital, analog, or mixed, and whether the speakers are passive or active. The transformation is immediate and deeply satisfying.
Each BACCH system comes with unlimited, live tutorial assistance from a BACCH expert to make sure it is working perfectly and to your satisfaction. This is provided via Internet with remote control of your BACCH system, while voice communication with your tutor is done by telephone.
JansZen is proud to be offering BACCH systems from our location in Columbus, Ohio, where we can provide demonstrations by appointment.
Please have a look at the Theoretica Applied Physics web site and then give us a call to answer your questions.