How much headroom can I safely enjoy? Some of my drum premixes are spiking maybe between 1 and 5 dbs above 0. I don't hear any distortion, though. Is that possible?

Thanks,
Jay

Sure it's possible, depending on how "0" is calibrated. There's no standard setting for "0" on a digital mixer (or DAW's onscreen mixer). Often it's -12dBFS or sometimes -18dBFS (the ADAT standard), but it could be anything.

Also, distortion on drums isn't necessarily a bad thing, depending on the context.

To sum things up:

As Nick said - in a _true_ 32bit-floating-point environment, the only place where you should take care fory any overloads is the point where the digital signal gets converted to a fixed-comma format, either for analogue output, or for digital connection to another piece of gear via conventional" S/PDIF-, AES/EBU- or ADAT-cables. Everything what is above 0 dBFS (read: "Full Scale") will distort the signal to some extent. A brickwall limiter as last instance sould take care for this, keeping the occasional overload just below 0.

As long as you send a signal from one (virtual) channel to another, the 0 db-mark can be considered to be a guiding line, but due to the enormous internal headroom of modern 32bit DAWs (high above +1000 dB!) there's no need to worry. The same is true for proprietary connections like FXTeleport and the like. The only problem you _may_ run into are plugins that don't do their calculations in true floating point math. Therefor, as a general rule, it is always a good idea to keep the gainstaging under control.

Of course, there are other concepts of DAWs like ProTools, which use no floating-pont engine. On theses systems, each red light has to be taken serious.

It is good to keep in mind that the "0 dB"-mark means totally different things in the digital and the analogue world. While there is actually no "life" above 0 dBFs in the digital domain, a 0 dB-mark in the analogue world is just a convention. It depends a lot on the context what actual level is reached when you hit these zeroes.

HTH,

Dietz, according to Digidesign it's impossible to distort their mix bus even though its internal resolution is 24 bits (with 56-bit accumlation). Do you disagree? Note that they're not making that claim about plug-ins, just the mix bus.

Also, while you obviously know this and one or two other things, I do think it's important for people to understand the difference between "0" on an onscreen fader or meter and actual 0dBFS. If you look at the meter in a mastering program such as a Waves L2, the meter shows the actual level; but often the standard mixer meters are set at a fairly arbitrary point. Plus they may have some kind of "analog" ballistics that show the "RMS" level rather than the peak.

(Is there actually a serious use for "average" metering other than to make people used to analog equipment more comfortable?)

Thanks Nick and Dietz.

--Jay

@Another User said:

(Is there actually a serious use for "average" metering other than to make people used to analog equipment more comfortable?)

Yes - with a little practice it is very easy to get a good impression of what's going on regarding the perceptible loudness (opposed to plain "volume").

I wasn't correcting you, Dietz, I was asking! You may well be right that HD is different. Since I downgraded my MIX hardware to an MBox 2 (which functions as a stereo digital I/O dongle so I can use the software), I haven't been keeping up with the details of HD as closely.

Indeed Digidesign seems to have put quite some effort to circumvent the problems of integer arithmetics. There is the 48-Bit mixer now for the HD platform which offers some 54 dB headroom:

http://akmedia.digidesign.com/support/docs/48_Bit_Mixer_26688.pdf">http://akmedia.digidesign.com/support/docs/48_Bit_Mixer_26688.pdf

I still don't like the sound of Protools if you drive it into red light. But I will check now what mixer plugin is used in the TV postpro studio where I have to work with protools. Could well be that they still use the 24bit mixer to lower DSP usage. The 24bit mixer is really ugly if you go into red.

Thanks for the hint.
(There's quite some confusion about floating point and fixed comma. I just had to edit a Wikipedia article (personal premier) which claimed PT is using floating point...)

Mathis, can you use the 48 Bit Mixer with MIX systems?

I don't know, but I don't think so. I guess you need serious DSP-power for that.

@Nick Batzdorf said:

I downgraded my MIX hardware to an MBox 2 (which functions as a stereo digital I/O dongle so I can use the software)

I've been considering doing the same thing. Need to occasionally open ProTools but really don't need the hardware. Is the Digidesign stuff getting along fine with Logic and your other hardware?

Yes it is, JJP. I don't even use the MBox hardware when I'm using other stuff.

What happened is that I've been using MOTU hardware as my mixer for a while now. Since MIX can't run on a G5, I kept it on my old G4 rig intact and just connected it via a 24-bit ADAT Bridge to the MOTU hardware, which does run on the G5.

But I got tired of doing that, and I'm very happy with the MBox now. The only thing I miss is the Sound Toys Pitch/Time Blender plug-ins, especially PurePitch (which I don't use often but have used to generate artificial feedback that I've added to boring guitar solos that just sit there on sustained notes).

At one point I even gave Digidesign my credit card # to upgrade to HD, but they were backordered and I grew cold feet. For the work I do (or was doing before I launched a magazine and will start doing again), it wasn't going to make me any more money. So much as I wanted to, I just couldn't justify the expense.

I want to keep up with the PT software, and now that it runs lots of tracks with the DVD Toolkit bundle, the LE system is perfect.

Thanks Mathis.

Thanks, Nick! Appreciate the info.