How to Calibrate an Analog Device in ProTools

Many mix engineers choose to incorporate analog devices into their ProTools setups. The effect is often preferred over the keepin the mix all in-the-box. This allows for a more hybrid approach to mixing and thus furthers the evolution of the modern digital audio workstation.



I will show you how to accurately set up the equipment with a simple calibration method. For this example I will be setting up a stereo analog compressor for insertion on the master buss.

Difficulty: Challenging

Instructions

Things You'll Need:

• ProTools HD or LE
• Waves Paz Meter
• Signal Generator
• Analog Compressor

1. When applying a stereo analog compressor it is common to calibrate the levels to ensure proper balance of the stereo image.
   
   We will first begin by creating a stereo master fader and one stereo audio track. On the master buss the fader is created with a default setting of 0dbFS. Leave it there.
   
   Insert the analog compressor to that buss. Now insert the Waves Paz Meter after the compressor. Set the Paz Meter to the fastest resolution (50). Leave it flat and to react to peaks.

2. On the audio track ensure that it too is at the same level (odbFS). Insert the stock Digidesign Signal Generator to this track.
   
   Make sure that the speaker volume is down low to avoid any loud bursts of noise, as this can damage your speakers.

3. Now check that the analog compressor is in bypass put powered on. Open the Signal Generator plug-in and lower it to 100Hz. Click the red "target" button at the top right corner of the plug-in to keep it visible, while you then open the Paz Meter.
   
   You'll want to check the meters at different frequencies to ensure that it is operating consistently. I typically begin with 100Hz, 1kHz and 10kHz.

4. Once you have determined that all is well you can now continue with your session.

Tips & Warnings

• As with all mechanical and electrical devices, analog equipment is prone to failure. I encountered an issue with an outboard compressor inserted on the 2-buss that had a faulty output capacitor on one of its stereo sides. It went undiscovered until it was pointed out by a mastering engineer that the bass in the song was -10 lower on the left side. I thought all was well as I was certain that the device had been properly calibrated from the beginning. It turned out that I had neglected to check it at 100Hz which would explain why there was an absence of bass on one side. Whoops!