Good morning, all! We have some tech news to report...
We've been using ProTools HD Native at 96K in both rooms for a few months now, and we are getting a pretty good handle on its capabilities (or lack thereof). A recent session with 55 tracks on a single socket MacPro (4 cores / 8 virtual cores) with only half the cores assigned to ProTools used less than 5% of the CPU, less than 20% of disk I/O capabilities, but 90 of the 96 available voices.
In other words, the voice limit set by ProTools is about four times too low for a half of a half of a modern day Mac.
As I understand it, playing back 55 tracks uses 55 voices, which by itself is no biggie. But if we want to bus, on average, one aux send and one stereo send per track, that would add another 165 voices! If we want those various aux sends going to 8 different aux busses and the stereo sends to 4 stereo group busses, that adds another 16 voices. Suddenly we're way past 200 voices, easily within the range of what the Mac could handle by itself, but well beyond the artificial limit of HD Native at 96K.
Thankfully, we have consoles. In the API room, our 64 channels have two inputs and our aux, group, stereo, and surround busses all have inserts, for a total of 128 + 32-ish input voices. Each channel can feed a direct out, 10 aux busess, 24 track busses, 3 stereo busses, and a surround bus, for a total of nearly 50 output voices, so a total of 3200 output voices. And then these aux busses and stereo busses have their own folddown matricies, for an additional set of voices. So in ProTools terms, the API console is about 35 times more powerful than ProTools HD Native when it comes to I/O.
In the Harrison room, we our 96 channels have two inputs, for a total of 192 input voices. (We can source from more than 500 distinct digital patch points, but those sources must be routed into the console before they represent a "voice".) Once inside the console, we have a direct out, 16 aux busses, 48 track busses, 8 group busses, and four stereo busses for a total of 80 * 96 minus the 8 busses that cannot route to themselves = 7672 output voices. So in ProTools terms, the Harrison console is about 80 times more powerful than ProTools HD Native.
In both rooms we have an Xdubber stem recorder (or two), which can record and play back 64 tracks in floating point. Thus, we can make a drum stem, a background vocal stem, a wall-of-guitars stem, etc., thereby actually *recovering* voices for ProTools as the mix gets bigger and deeper. When we mix in the API room, we can source ProTools from one fader and the Xdubber from the other: 64 + 64 inputs all day. In the Harrison room, we can have fader-per-channel on 48+48 inputs or do more creative things to use the B inputs for natural summing (such as source + efx
return and controlling efx
level based on efx
send rather than fader return), allowing us to use more of the 64 channels of ProTools or more of the 64 channels of stems, whichever way the session goes.