Billy Buck are you saying when mixing turn on that mic icon to cut cpu?
The LiveTrack mode will
increase native CPU use as the UAD-2 plugins are essentailly running off your native CPU. Quite interesting to see how much native CPU a UAD plugin uses. One stereo instance of the upsampled FATSO (with tranny enabled) uses about 21% of my E8400 (3Ghz) Core 2 Duo when in LT mode @ 128 samples ASIO. With LT mode disabled the native CPU load drops to near zero (about 0.6%) as all the processing is done off the UAD-2 DSP at that point. It kinda makes the WaveArts Tube Saturator look rather CPU light in comparison.
Thank God for my UAD-2 QUAD, as I can easily run (8) upsampled FATSO's (with tranny enabled) and my total native CPU hit is about 4% @ 128 samples and still have about 20% DSP left for lot's of less DSP intensive plugins. I can only get (2) FATSO's running in LT mode crackle free, but adding a third will give the rice crispies as my native CPU is pushing 60%-70% wilth just those three plugins.
You would not use LiveTrack mode when you are in the mixing phase as it is not necessary (with DAW's that have auto PDC), and will only burden your native CPU. Where the LiveTrack mode does come in handy is when you are tracking/overdubbing or want to run a monitor mix and are using UAD-2 plugins at lower latencies. You would only enable those plugins that are affected. Say you have a 1176LN in the FX bin with your favorite amp sim and you want to record a new track or overdub using the 1176LN in "All buttons mode" to add a little more bite in combination with your amp sim. Set your project latency to say 128, enable input monitoring and simply enable the LT mode on the 1176LN and now you have zero plugin latency when tracking. When you are done tracking simply turn the LT mode off as you don't need it when playing back.
What LT mode does is eliminate the inherent plugin latency that you get when using a DSP card. The time it takes to shuttle data to/from the card. For the UAD-2 this equates to 1x whatever the project latency is set at. If you are at 1024 then each UAD-2 plugin adds another 1024 samples to the total plugin latency (total 2048). If at 128, each UAD-2 plugin adds 128 samples to the plugin latency (total 256). The LT mode eliminates this extra processing overhead as it bypasses the I/O processing transfers to/from the DSP card and uses the native CPU instead. You can easily verify this in REAPER using it's plugin analytics. Using the 1176LN as an example, insert it into a project using a 128 project latency and you will see the PDC correctly state 128 (1 x the project latency = 128). Now simply enable the LT mode and watch the PDC suddenly drop to ZERO. No more plugin latency, as the DSP card's I/O is now bypassed and the native CPU takes over.
post edited by Billy Buck - 2010/02/05 12:31:31