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Help With Encoding Quad In Audacity

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#1
(Moderators/Adimns, forgive me if I post this in the wrong thread)

Hello all, I've been playing around with encoding/mixing some four channel tracks down into stereo using the two simpler non-phase shifting formats, Dynaquad and EV-4, in Audacity with little success.

I start by splitting the front and back stereo tracks into four single left/right tracks and duplicating them into eight so I can apply their respective inverting/amplification values to achieve the two L/R Total tracks. So, using Dynaquad's formula for example, for LT I keep LF as it is, reduce RF to .25 (about -12 dB), keep LB as it is, and invert RB while reducing it by .5 (-6 dB). I then take these modified four tracks and mix them down into LT (which actually has a separate right track (thus stereo)) and repeat the procedure for RT, but swapping values/polarities. In the end I get two complex stereo channels which I reduce down into one.

Now, I believe I was doing things right until I began decoding it using a slew of receivers and adaptors, ranging from my main Toshiba SA-504 on its RM setting, my Lafayette LR-220 on its "Composer" setting, and a crummy Realistic Quatravox box with absolutely no success. For starters, I do get frontal stereo separation, but the back seems nonexistent, perhaps even mono. Now, I know Dynaquad/EV-4 practically has no back stereo separation (2 dB if I recall), but I should at least hear something moving around. I also hear hardly any of that ambient out of phase difference in the back, and my test tracks contains a lot of stereo reverb. My only guess is I should mix the 'unwanted' channels (like RF/RB in LT and LF/LB in RT) in mono and then mix them in instead of having them retain their stereo information.

Any suggestions are welcomed!
Thanks!
 

Snood

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#2
Hiya Senoverde welcome to QQ :LB

Please be patient and I am sure a more than a few QQers will be along to help ya. :love: - We are world wide so half the planet is asleep now:sleep: except Snooooooooooood:SG
 
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#3
that all sounds like too much work to me. Here's what I would do - duplicate all tracks (4 stereo to 8 stereo) then hard pan each pair, then render the whole thing to one stereo track. If you want to you can experiment with the panning (less than 100% left or right) on the different pairs or whatnot. I'm not sure how you get 4 stereo tracks out of a quad recording to begin with, it should be 4 mono tracks.
 
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#4
that all sounds like too much work to me. Here's what I would do - duplicate all tracks (4 stereo to 8 stereo) then hard pan each pair, then render the whole thing to one stereo track. If you want to you can experiment with the panning (less than 100% left or right) on the different pairs or whatnot. I'm not sure how you get 4 stereo tracks out of a quad recording to begin with, it should be 4 mono tracks.
It's either mix it all down manually or find a vintage encoder. :p To be honest, I don't mind it actually. It gives me a good sense of how these simple amplitude/polarity based encoding systems work.

You were totally right with having mono tracks from the start (DOH!). What I kept ending up with was a LT signal that had LF+LB on the left channel, and .25RF-.5RB on the right of the same stereo track. Same was true for RT (but reversed channels). Obviously we need that .25RF-.5RB mixed together with LF+LB. You can see why everything sounded like it got cancelled down to mono.
 

HomerJAU

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#5
I know it can be a bit of fun playing with this but why not just keep your mixes as discrete 4 channel files? Encoding/decoding to/from stereo isn’t going to be as discrete as 4 tracks.
 

boondocks

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#6
If you might like to play around with an alternative piece of software, I reccommend Plogue Bidule. I and others have been using it for years to do 5.1 "upmixes" from stereo with our fave music for which there is no commercial release in surround.
But there are other things you can do with it, and as you get more proficient with the software you find more capabilities.
However if the "upmix" part sounds good you can go here and pick up some free software to use with your copy of Plogue Bidule: http://www.surroundbyus.com/sbu/index.php
Although I suspect he's awfully busy these days, "Zeerround" on that forum know more about Plogue than anyone else I know.
 
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#7
I know it can be a bit of fun playing with this but why not just keep your mixes as discrete 4 channel files? Encoding/decoding to/from stereo isn’t going to be as discrete as 4 tracks.
My goal from the beginning was to use matrixing over discrete. Why? Simply put, my target listeners can't be bothered with multichannel amps and the likes, or in other words... they're dumb non-audiophile folk. ;)

If I can use a system that can decoded back through something as simple as a Hafler Circuit with a few resistors or any of the various passive decoder boxes from the 70s, maybe I can reach a few more listeners. Adding two extra speakers is a heck of a lot easier than buying a new multichannel receiver. Is the separation crap? Yes. But thankfully most of the things I'm mixing are a bit on the ambient side where I don't need to plop sounds discretely in a single speaker.

I'm still floored by Jean-Jacques Perrey's Moog cover of "Flight of the Bumblebee" on that Dynaquad demonstration record.