Originally posted by RKrizman
True, it doesn't make sense to lower your bit rate of the ITB mix and then up it with the preamp. That won't tell us anything. So how about this. Instead of sending all the individual tracks to the Folcrom, just sent the ITB 2-mix to 2 channels. Compare that to the individual channels summed in the Folcrum, without changing the fader levels in Protools. Wouldn't that make all other things equal and merely test whether external summing makes a difference. (Now, if you tell me that just sending 2 tracks will change the load or whatever, then I think the box has a problem. )
There won't be any impedance or loading problems when you do this. The only problem I see is that the total make-up gain necessary from your preamp will probably be slightly different for a 2-mix going into 2 channels of the Folcrom than for 16 channels going in separately. I'm not positive, but I suspect that the net level coming out of the Folcrom would be different. You'd have to change the gain setting on the preamp, which could change its sonic signature. But I do think the comparison you're interested in is a valid and important one. Here's how I would do it:
1. Determine the signal level coming out of the Folcrom when you have 16 channels of audio feeding it.
2. Determine the signal level coming out of your DACs when you feed nominal level out of them.
3. subtract #1 from #2 and you'll have an attenuation in dB. build a 2-channel U-pad that has an input impedance of 10k-20k, an output impedance of 150 ohms, and an an attenuation equal to what's calculated above.
4. Feed your BTD mix out through 2 DACs (the same type you did your 16-track Folcrom mix with), into the special pad you built, and then into your 2-channel preamp which is set for the same gain setting you had for the Folcrom mix.
5. Do a null test or other such comparison to make sure your two mixes are level matched to within 0.1dB. Adjust the pad or your BTD output faders accordingly until you can get a mix matched precisely to the Folcrom mix.
6. Now listen to the three mixes (BTD, BTD through pad and pre, and Folcrom). Report back to us on your findings. I'm pretty confident I know how it'll turn out, but if you want to be "sure" then this is what you need to do. Once you figure out the attenuation you need in the pad mentioned in #3, I can help you figure out the resistor values. In fact, I'd even be willing to build a couple of inline pads of the appropriate value if somebody is serious about performing this test properly.
It's an interesting question about the possibility of upping your faders when you go out to the Folcrom. I don't know, but it seems that when I mix in Protools I usually have a track or two that is bumping up pretty close to zero, with the other tracks down lower according to how they need to sound. If I go out to the Folcrom, I can't bump those tracks up any louder, and can't bump up the other tracks, obviously, without changing my mix.
If you leave some of your tracks up at "zero" don't you need to pull down your master faders to avoid clipping the 2-mix? I don't use a multitrack DAW, so I don't know. I was under the impression that if you have a lot of "loud" tracks then your ITB summed mix will be "loud" too, and require that you attenuate it somewhere. I thought this is what Bang was talking about, because when you mix outside the box, you don't have to worry about that.
All your automation moves will still be intact and to recall you mix you merely need to note the trim level on each analog channel.
This is one of the big reasons why I decided to keep the Folcrom passive and without any trims or pots at all. I've found it is impossible to recall a mix based on "making note" (or even taking a photo) of the positions of analog pots. It always sounds different when you try to recreate a mix on an analog board. The Folcrom at least gives you the option of maintaining real, absolute recallability from the DAW. You're still free to give that up in order to patch in analog processing gear between the DAW and the Folcrom, but if you want the recall, it's there waiting for you. The Folcrom only has 4 discrete assign possibilities per channel, so you can't set it up "a little bit" differently.
My point with all this is that once you know what's really causing the better sound, then you can go there and make the most of it.
Interesting discussion, and lots of good points have been made.
I couldn't agree more. I'm really glad to see all this terrific discussion going on while I wasn't paying attention.