One of the biggest issues Protools LE users have to deal with is latency, whether it’s plugin latency or the delay heard when not using direct monitoring on an Mbox. What I will go though today is measuring the delay when using outboard gear, specifically with the Digi002, and what to do about it to correct the problem. This tutorial should be helpful for anyone that wants to use outboard gear in their computer based studio.
First lets create a new session and add two mono audio tracks. Name the first track Send, and the second Return.
Now set your main timescale to Min:Secs. On the Send track make a selection of 1 second. In the Audiosuite menu under Other select Signal Generator. Set the level to -6dB and process. Close the signal generator plugin.
What we are going to do is send this tone out of the interface, into a piece of hardware, and record it back into the interface. We can then zoom in on the waveform and see how far off the start is from the original.
Now lets make the connections: Please mute the Return track to prevent feedback sent to speakers, in fact you may want to mute your speakers. Set the Input of the first track to No Input and the Output to Interface-> Analog 3 (mono). Set the Input of the return track to Interface ->Mic/line 1 (mono), and Output to Interface ->Analog 1-2 (Stereo). Now take a 1/4″ cable and connect one end to Analog out 3 and the other end to your hardware’s input jack. Connect another from the output of the hardware to the Line In 1 jack.
Turn on your device and lets check levels. Unmute track 2 and push it’s record enable button. Play the tone a few times and set the gain on the input to match the -6dB send level.
Record the returned tone.
Switch the edit mode to Slip and your timescale to samples. Zoom in to the start of the waveform, notice the gap? If you select the gap, you can make the length of the delay your nudge value and then when mixing you can nudge the track being sent earlier in time, so that it ends up being on time when it returns. Get it? Hopefully this picture will help.
Bigger pic here.
While writing this tutorial I was using a Line-6 DM4, I found a delay of about 44 samples @16/44.1, no matter what the buffer size, with or without low latency monitoring.
