Another Summing Thread

[dannygold]

I have mixed a couple records in DP. Although generally happy with the results, my bandmate has complained about a the lack of stereo imagine width. He's not very technical but has good ears. I find this interesting because he didn't know about the whole DAW summing debate, but kind of heard one of the classic alleged symptoms of DAW summing suckage.
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So I've been doing some testing. I did a simple mix with identical pan/level setting in three DAWs, DP, PT and Logic. Phase inversion/cancelation tests showed that the center channel was the same between all daws (eg things panned up the middle were summed identically). I know this because when comparing two mixes with one phase inverted things panned up the middle canceled out completely. I'm sure someone will argue the merits of that test, but I think most of you who understand 180 degree phase cancelation will accept it. Things panned hard left and right were NOT summed identically. I know because they didn't cancel out when doing the phase inversion test. That part is fairly scientific I feel. What's not scentific is how they sounded. I felt Pro Tools had "louder" and possibly "beefier" material on the "sides" (things panned left/right). DP and Logic almost seems to be attenuating the panned elements.
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It's kind of disconcerting that three DAWs would sum differently IMHO, although hardly surprising because Pro Tools uses 48 bit fixed summing MOTU uses 32 bit floating point, so the math is done differently. Anyway, one possible solution to my bandmates complaints might be to bring up the "sides" in mastering (mastering engineers can separate what's panned center from what's panned L/R). If DP indeed attenuates things panned hard, that would make the center info more dominant and result in a more mono-like mix. and kicking up the sides a little might fix that.


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The other solution would be analog summing. I put this in low end theory because I won't be buying a 4K summing box. I might have a friend build a passive summing summing box. These boxes knock down the signal by about 30 db and then you make it up with a mic pre. The guy from FMR audio who I think is generally considered an honest guy said the RNP (which I already own) would do a fine job of adding gain back after running stems thru a passive mixer. What do you guys thing about that? Does that sound right? Anyone have any other low end analog summing solutions? Anyone tried the SM Audio PM8?

Danny Gold

[dannygold]

Other ideas... A company like MOTU or DIGI could solve all this a couple ways. One would be an audio interface with built in analog summing (and a high quality clock d/a, etc). Another would be a mode where you feed the DAW a bunch of stereo stems and it sums them in a higher quality mode, like 72 bits or something. Obviously a DAW would choke if it did that for normal operations, but I see no reason they couldn't write in a "HQ summing Mode" where stems were summed with higher quality math so we didn't have to break it out to analog just to fix the summing.

[donsolo]

why don't you just plan on it and do your own M-S processing?

basically you're creating two mono tracks, M and S
take L and R and output them (in mono) to the same mono Aux Track labelled M this is how mono foldown works anyway.
Take L and R (add phase invert to R) and output them (in Mono) to the same Mono Aux track Labelled S.
basically L+R = all the information in the middle and L-R=all the things left on the side Because the information that's exactly the same on both sides will cancel out with the inverted phase.

THEN, you bring up S by 2-3 DB
THEN, repeat these steps replacing L with M and R with R and route to a single stereo aux.

Theoretically, that's M-S processing.
PM me for my cell and office number if you have questions.

The OTHER way to do it is to use the Waves M-S matrix, it converts L and R to M and S without all the extra aux tracks. It creates all the summing.

The OTHER thing you can do is take your ear candy and double it and invert the phase. It's going to disappear completely in a mono foldown but that's extraneous information for your mono mixes anyway. Best thing that'll happen is that your stereo image will get 180degrees wide. DP is somewhat mono sounding, that's why I make sure to compensate.