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Hmmmmm
Matrix vs Discrete
- Thread starter MidiMagic
- Start date
Help Support QuadraphonicQuad:
Here's hoping that means "Hmmmmm - that's an idea worth considering" - rather than " Hmmmmm - are you kidding me?".
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Anyone have any equations for pre-processing stereo for the SM for deriving surround sound from stereo?
Kirk Bayne
Kirk Bayne
In the simplest of description:: take stereo left ch, invert phase & mix with stereo right ch at -7.7 dB
Take the stereo right ch, invert phase and mix with left ch -7.7 dB.
Here is how I did it with hardware:
https://www.quadraphonicquad.com/forums/threads/chase-rlc-1-meets-the-involve-sm-v2.26882/
Hardware implementation can be much simpler than that. @par4ken has posted a simple circuit to do this.
Here is how I currently do it today, by software. Much more control & much simpler than to do a full upmix:
https://www.quadraphonicquad.com/forums/threads/stereo-pre-synthesis.25299/
If I can confuse you any further, just let me know...
MidiMagic
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I HAVE one. I call it a Phlazex
Here is the schematic:
In the Phlaze position, it adds blend or antiblend from one channel to the other channel.
In the Encode position, it lets one or both channels be phase reversed.
The Phlaze position can add blend or antiblend to both channels, allowing you to shift the QS image forward or back.
I use the Encode position (left-biased or right-biased) inserted into the 3-4 mixing buses to encode RM back positions in a standard 4-bus mixer.
Here is the schematic:
In the Phlaze position, it adds blend or antiblend from one channel to the other channel.
In the Encode position, it lets one or both channels be phase reversed.
The Phlaze position can add blend or antiblend to both channels, allowing you to shift the QS image forward or back.
I use the Encode position (left-biased or right-biased) inserted into the 3-4 mixing buses to encode RM back positions in a standard 4-bus mixer.
Honestly I don't think there is anyone on the forum that has any interest in, much less building, all the wacky transformer L-Pad things you keep posting. Most of us have moved on to something better. This century .
MidiMagic
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I made them because they require no power supply. They can be used anywhere (home, car, or with a live band) without modification. And they have no active-component distortion. They cost very little, they work, and I use them.
I originally built an active IC version of the Phlazex for a musician to use in his studio. He kept having trouble with it clipping in the mixer section when he fed two unintentionally oversize-amplitude signals into the inputs. I gave him the current version and he had no further trouble. You can't make it clip.
Any preferred settings (for popular music, maybe so a stereo source can sound more like the Quad mix of the AWB album, for example)?
Kirk Bayne
Are you building one Kirk? What Sonic has said would still apply -7.7 db of blend will cause extreme left and right panned signals to play from the back speakers. Subjectively a bit less blend would be fine, adjust to taste!
This type of enhancement pulls the stereo mix apart in a 270° horseshoe pattern. Results depend on the original mix. It is very unlikely to produce the exact same result as the discrete version, they are two different animals each with differing mixing choices.
I have no plans to build a stereo pre-processor, I was just interested in what happens with popular music.
Kirk Bayne
Kirk Bayne
Obviously it can't encode from a discrete quad source.
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