Mixer Test / PT Sound Quality

[Jonny Atack]

Hi all,

Our studio crew and I read with great interest Dave Lebolt's announcement of a dithering mixer plugin test.

We downloaded the two mixers A and B last night from the digi site. Interestingly enough, mixers A and B use less hard disk space (520kb each) than the 24-bit Optimized Mixer (780kb). Digi, is this a full service mixer plug? How did you get more into less code?

Using PT 24 MixPlus 4.3.1, we followed Dave Lebolt's instructions in the "ProTools Sound Quality???" thread, except after bouncing both versions to disk, we re-loaded the original 24-bit Optimized Mixer plug v.1.7.2 for the listening test, as per Rail's suggestion.

Source: a 24-bit, 20-track rap song with NO plugins.

Conclusion: A subjective preference for Mixer A. However, my slight suspicion that that there was no real difference between the two was confirmed by swapping phase polarity and mono panning on a stereo aux send. All cancelled out leaving zero audio.

Digi, is one of the mixer plugins really dithering as you described? It's difficult to believe that using dither would have no effect. Is is necessary to turn the computer off between mixer plug swaps in the DAE folder? I was just quitting PT between the swaps without shutting down.

Jonny


[This message has been edited by Jonny Atack (edited December 12, 1999).]

[Jonny Atack]

What results have you all been coming up with?

Best Regards.


[This message has been edited by Jonny Atack (edited December 13, 1999).]

[Dave Lebolt]

Yes, the mixer that is supposed to be dithering is really dithering.

[Rail Jon Rogut]

Hi Jonny

I've been too busy to do any tests yet... but I've set up a tentative date to do the tests in the Oxford room on Wednesday -- I'll let y'all know what I find.

Rail

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Recording Engineer

[Dead Space]

After one not-so-strict test, I too have a preference for mixer A. I used a very rough mix of an unfinished track with only drums, bass, and a stereo acoustic guitar (no plug-ins).

I also did the phase flip test and had the same null results for both mixers. Weird. Maybe the difference signal is so far down that it isn't audible by itself, just buried in the noise (or perhaps it IS noise. It's dither right?).

I also seemed to notice a bigger difference when I was actually using the different plugs while mixing as opposed to the actual side-by-side listening test of bounced mixes. It's probably just my imagination.

I'm doing a strictly strict test later of a finished track to see if I change my mind.

[This message has been edited by Dead Space (edited December 14, 1999).]

[Dave Lebolt]

Please read my new post on the thread labeled "Pro Tools Sound Quality (continued)???" to make sure that you're getting the dither working... the new mixer *presently* won't work with "vintage" DSP Farms, or if you have "declared" I/O connected to vintage DSP Farms.

[Jonny Atack]

Dead Space,

Yes, the difference also seemed greater to me too when I tried it on a 32-channel mix with many plugins, including R-comp and L1+ on the master fader.

I did the phase switch in mono with that as well, and the two mixes didn't not null out all of the time. Sometimes a solo vocal or instrument was coming through. But I suspect this was due to micro-delay variations from the plug-ins, especially Auto-Tune, rather than to the mixers.

So the subjective difference must have been imagined...


[This message has been edited by Jonny Atack (edited 12-15-99).]