BACCH and other XTC

[Lion♡]

Hi
I am new to this forum.
I am using Ambiophonics/DCH with some breaks for almost 20 years, since my first demo and consultations with Mr. Glasgal. He ruined stereo for me forever.

Welcome, and thank you for sharing your experiences.
If it’s not too much trouble, could you please show your spectrum as an image?
I’d like to see the ILD difference and the degree of response degradation in both ears for race/bacch/xtalk.

 

[fcserei]

If it’s not too much trouble, could you please show your spectrum as an image?

Could you please explain what would you like to see.

 

[chichi]

Hi,

Has anyone run into an issue where as the sound image get closer to the center, the overall level after crosstalk cancellation output noticeably drops?

Here’s the workflow in question:

1. I start with a mono track.
2. I apply an HRTF to generate a binaural signal, so the source can be panned around the head (headphones required for correct monitoring). Everything behaves normally up to this point.
3. I then feed this moving binaural signal into a RACE‑based XTC algorithm. As soon as the virtual source approaches the center position (azimuth = 0°), the output level falls off.

Has anyone observed the same behavior?
Thanks in advance!

 

[Tim Link]

Hi,

Has anyone run into an issue where as the sound image get closer to the center, the overall level after crosstalk cancellation output noticeably drops?

Here’s the workflow in question:

1. I start with a mono track.
2. I apply an HRTF to generate a binaural signal, so the source can be panned around the head (headphones required for correct monitoring). Everything behaves normally up to this point.
3. I then feed this moving binaural signal into a RACE‑based XTC algorithm. As soon as the virtual source approaches the center position (azimuth = 0°), the output level falls off.

Has anyone observed the same behavior?
Thanks in advance!

It's interesting to think about what might be happening there. How far apart are the speakers? It makes sense that when the level reaching each ear is identical the crosstalk reduction becomes most aggressive, perhaps to the point where it reduces the level at your ears overall.

 

[chichi]

It's interesting to think about what might be happening there. How far apart are the speakers? It makes sense that when the level reaching each ear is identical the crosstalk reduction becomes most aggressive, perhaps to the point where it reduces the level at your ears overall.

Thank you for your reply!

My current setup is as follows:

1. The distance between the two speakers is 12 cm.
2. The listener sits 60 cm in front of the speakers.
3. From these numbers, the speakers’ subtended angle works out to 11.42 degrees.

The XTC algorithm I’m using is my own implementation based on the RACE concept, and I suspect that’s where the problem originates.
In fact, as soon as the input signal—binaural audio with the virtual source placed dead‑center via HRTF—passes through my custom XTC, its level changes. I can see this directly in the DAW without even listening:

The image on the left is before processing; the one on the right is after, showing roughly a 3 dB drop.
Because RACE effectively subtracts each channel from a time‑delayed version of the opposite channel, an extremely short delay brings it very close to full cancellation.

I’m wondering whether my implementation is simply too crude and if I’ve missed some important considerations.
I’m not sure whether this discussion belongs in this forum, so I would greatly appreciate any guidance. Thank you!!

 

[Tim Link]

Thank you for your reply!

My current setup is as follows:

1. The distance between the two speakers is 12 cm.
2. The listener sits 60 cm in front of the speakers.
3. From these numbers, the speakers’ subtended angle works out to 11.42 degrees.

The XTC algorithm I’m using is my own implementation based on the RACE concept, and I suspect that’s where the problem originates.
In fact, as soon as the input signal—binaural audio with the virtual source placed dead‑center via HRTF—passes through my custom XTC, its level changes. I can see this directly in the DAW without even listening:

View attachment 449042 View attachment 449043
The image on the left is before processing; the one on the right is after, showing roughly a 3 dB drop.
Because RACE effectively subtracts each channel from a time‑delayed version of the opposite channel, an extremely short delay brings it very close to full cancellation.

I’m wondering whether my implementation is simply too crude and if I’ve missed some important considerations.
I’m not sure whether this discussion belongs in this forum, so I would greatly appreciate any guidance. Thank you!!

That's a very nearfield setup. I've tried running my own race implementations as well, and found I had to back off the aggressiveness of the crosstalk reduction to something that didn't produce quite as wide a soundfield. If it went to full 180 degrees it sounded lost and confused to me, although I never measured the level drop of the phantom center, I assume that had something to do with it.