Re: Mixing in analogue -- here we go again!
PART VII. MONITOR CALIBRATION
Having a reference volume level can be invaluable when you are trying to determine how your mix stacks up against others in terms of loudness. It also gives you a definitive baseline to work off of since every 10dB SPL equates to a subjective doubling of volume, if the volume level is too loud at reference, you can roll it back 10dB and you know you are at about 50% of total loudness at that point.
To calibrate your monitors you need the following:
- a signal generator
- a monitor controller with dB markings
- an SPL meter
- your monitor chain
In this case, my DAW is providing the signal generation; the monitor controller is the SM PRO Nano Patch; the SPL meter is an analogue Radio Shack model; the monitor chain is as described earlier (Desk > DAW > monitor controller > monitors).
1. Place an EQ and signal generator on the mixdown track of your DAW.
2. Set the generator for pink noise, -20dB.
3. Bandpass the EQ at 200Hz and 5kHz; basically you are calibrating to the most sensitive rang of hearing, the midrange.
4. Set up the SPL meter for C weighting, Slow response. Place it on a stand pointing up, placed at the listening position.
5. Set the monitor control at 0dB.
5. Power on ONE MONITOR. Raise the level until the pink noise is at your SPL reference level; in my case, 74dB SPL is my reference for -20dB DFS pink noise.
6. Turn off the first monitor and repeat with the second one.
7. Turn on both monitors and verify that you are reading +3dB with both of them at the same level at the same time.
That's it. Now the monitors are calibrated for 74dB SPL at -20dB DFS.
VIII. MIXING DESK CALIBRATION.
Calibrating the desk is a very similar process, but without bandpassing the pink noise, so it's running full range.
With the desk's output at 0dB, bring up one channel, panned left, to 0dB. Adjust the trim until the input level for that channel is at your reference. In this case, our reference level is -20dB DFS, so we are looking to hit -6dBu on the desk.
Since we are using so many outputs from the interface and the ADAT breakout, I like to use a separate calibration session, with everything routed. I put EQ and tone generators on each bus so I do not have to change wiring. This way I can kill 2 birds with 1 stone: I can verify the wiring and signal routing is correct, and I can calibrate the hardware.
When that is done, I repeat the process with the channels panned according to what bus they will be serving. I then tweak the trim until they are matched in level.
And that's it! The entire process takes an hour or so depending on how many channels your desk has.
Photos to follow, I am typing this while on a service call.
