BACCH Stereo Purifier
Stereo is supposed to be a completely solved problem. As something of an expert in audio, my amazement when I first heard a BACCH system was tempered by the gap that this revealed in my previous understanding. I learned that standard stereo is missing something.
Three approaches to recovering some of the experience missing from standard stereo are 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. BACCH exposes the additional musical experience locked in your recordings, rather than adding extra sound.
A BACCH system places you in a magical, musical space with no sense of speakers or walls, and does so without introducing distortion or sonic artifacts.
You may be familiar with systems that widen the soundstage and so on, 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 quick 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.
First, an obvious point is that a live performance is wider than the space between a pair of speakers, and includes the sound of the performance hall. When listening at home, however, we accept that a playback image is mostly confined between the speakers.
When crosstalk has been reduced, however, you'll hear the actual image fully in all three dimensions. With some recordings, given treated first refection points in the room, 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 better experience the performance space.
When your eyes are closed, while a two-microphone or binaural recording is being played back, the sensation can be very close to hearing what the microphones heard.
To sum up this point, by cancelling crosstalk to a high degree, the BACCH system unlocks the hidden gloriousness of even the most glorious stereo recordings, and this is thrilling. 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 the model names stands for.
2) This point has to do with further reducing the effect of your room ambiance and speaker design, regardless of room treatment.
With conventional stereo, your room alters the sound substantially. In fact, standard stereo depends on a certain amount of local ambiance to work. Unfortunately, almost never does a room's reverberant and reflected sound match the sound that comes directly from your speakers, so in a sense, its presence can be considered a form of distortion.
If we care to unlock all the hidden treasures on your recordings, aside from cancelling crosstalk, then it helps to hear clearly the ambiance of the room or hall where the recording was made. A unique form of ambiance correction completes the BACCH method to making your room disappear, transporting you to the original performance space. It's ORC, for Optimal Room Correction.
The ORC 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
The effect is an astonishing 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. 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 sound coming from all directions. This causes an inherent brightness or sometimes stridency in live two-channel recordings where the engineer hasn't addressed the issue, which is most of them.
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 where the performers usually are in front. Your ears hear things differently when present at a performance, so the substantial sound that comes back from the side and rear walls of the performance space are reproduced somewhat differently than you'd hear them live.
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 an 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, you can turn it off.
4) Lastly, all speakers have anomalies of one sort or another in frequency response and phase coherence. You may hear this as a tendency of your speakers to sound better on certain types of music, or to only come alive above a certain loudness, or the image seems recessed, etc.
In addition to implementing optimal room correction, ORC will correct most speaker response anomalies, and until you hear it for yourself, it can be hard to believe how transformative this enhancement can be. Of course, you may prefer your speakers as they are, in which case you can just turn that part of ORC off.
Conclusion
BACCH can be integrated into practically any stereo playback system. The transformation is immediate and deeply satisfying.
Each BACCH system comes with unlimited, live, expert tutorial assistance to make sure it is working perfectly and you feel confident. Live tutorials are provided via Internet for remote control of your BACCH system, and voice communication 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.