Pro Tools Sound Quality???

[Rail Jon Rogut]

Dave, in your original post you wrote a description of how to perform the AB test:

Here's a tip about how to set up a good A/B test:
1. Create multi-track mixes with different program material. (I say multi-track, because this is where people said they heard a difference most… with multiple tracks and gain changes.) To be as objective as possible, don't use any DSP Plug-Ins.
2. Bounce the mixes to 24-bit stereo files using the two different mixers.
3. Import the results (the two pairs of dual-mono files from the Mixer A and Mixer B bounces) into a new session. Line them up on two grouped track pairs.
4. Go to Preferences/Operations, and uncheck the option that is normally enabled for Solo buttons to "latch." This allows you to instantly switch between two mix stems using the solo buttons.
5. Listen back, and switch soloing between the pairs to try to I.D. any differences.
6. With your new "comparison" sessions, since you're not changing gain (setting faders at unity), there should be no difference between the two mixers… use either one to check the results.
7. Perform a blind-fold test: have someone switch the results without your seeing (or hearing) them switch. If you want it to be really honest, the operator will not even switch all the time, and certainly not when "cued" by you as the listener. This forces the listener to actually identify when and if the sound has changed. If you're not accurately identifying a difference greater than 50% of the time, you're statistically not hearing any difference. (I've been tripped up on this a few times… try it!)

However, because the new mixer always dithers, I think that before step 5 - the mixer should be changed back to the old original shipping 24 bit optimized mixer for a true valid comparison.

Thanks.

Rail

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Recording Engineer

[Juicy]

Unfortunately, the bulletin board software doesn't appear to support creating links to FTP sites. UBB Code appears to prepend "http://" to the beginning of the URL, no matter what. Take a look at the status bar in your browser when you mouse over the FTP link.

-B...

[Jules]

The epic instructions & then debates as to how to set up to judge the results are a little worrying.
Good luck to the remaining few propellerheads! Let us "ears only" folks know how you got on when you have a break from "the lab"!

Jules

[bcobin]

Just found out about this thread... Suffice it to say that I've done the mixer comparison on a full mix and the results are very revealing indeed...

There is no doubt in my mind which mixer I'll be using from now on... If you're mixing in PT, you want to try this...

-b

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

[ProdInfo]

Greetings!!!!

This thread has become rather large and our system has difficulty indexing it. So, I'm closing this thread here, but re-opening one called "Pro Tools Sound Quality (continued)???"

http://duc.digidesign.com/showflat.php?Number=29413

Please post under that new section. Thanks.

Webmaster

[Dave Lebolt]

Folks,
If you're doing these tests, I have one more piece of information for you: I have just found out from the developing engineer that the dithering on the special mixer will only work on MIX cards. The amount of DSP required to do this on the older "vintage" DSP Farms makes it impractical to support. Just wanted to make sure you were all aware of this.