Bryan Chow

R=R+0.5*C... Should it be 0.5 or 0.7071 (ie. 0.5*sqrt(2)) ? Since audio volume is logarithmic would it take 0.5*sqrt(2) in each front channel for the center channel to be at the right volume level?

You can also apply the Hafler circuit commands to your front channels to hear what the rears would sound like. You'll know it's working correctly if mono music becomes silent, while stereo music generally have vocals reduced (or even disappears) and you hear more audio that sounds like ambient cues.

I do use Peace sometimes but it overwrites my complicated config.txt so I have to back it up, run Peace, find the commands then incorporate them into my config.txt which is a bit of a hassle. What I find really useful is the Editor, especially for visualizing my filters from REW together with my Equalizer APO filters and preamp commands. You can consider using the term "ambiphonics", which the Hafler circuit is a type of. It will be cool to see it in Peace :)

I've tried quite a few types of music and recordings they all work quite well. On some recordings (musicals etc with centralized vocals), the vocals pretty much disappear from the rear. On others like pop music the effect is less pronounced, but I also hear different instruments emphasized in the rear channels depending on how they are mixed in the left and right. It feels much more natural than copying front to rears. I tried to post a recording to YouTube for you to hear but the video was muted...

Yes! Any sound common in both speakers is removed, you're left with ambient cues. So compared with what I did before (copy front to rear), I no longer get vocals behind me which makes sense. Technical rationale, from wiki: "The rear ambient sounds, applause, and coughs from the audience are sometimes received out of phase by the stereo microphones, while sounds from the musicians mostly are in synchronous phase. Thus, if rear speakers are fed with the difference between the stereo channels, audience...

Yes I do have the pre-mix command. Thanks Peter! The Hafler circuit ambient surround sound is quite interesting. Seems to be more pleasant than just copying fronts to rears (with reduced volume).

Ok I figured it out: Copy: LSHIFT=-1.0*L Copy: RSHIFT=-1.0*R Copy: SL=L+RSHIFT Copy: SR=R+LSHIFT It seems to work, when L and R channels are the same (stereo mono) the surrounds are silent.

I was watching this video https://www.youtube.com/watch?v=SNsmG7HHczU&ab_channel=PSAudio and am intrigued by it. It's called a Hafler circuit https://en.wikipedia.org/wiki/Hafler_circuit Hafler decoding matrix Left Front Right Front Left Back Right Back Left Total 1.0 0.0 1.0 -1.0 Right Total 0.0 1.0 -1.0 1.0 Right now I'm simply copying the front channels to the rears for a fuller sound: # Upmix stereo to 4-channel If: inputChannelCount == 2 Copy: SL=L Copy: SR=R Channel: SL Preamp: -3 dB Channel:...