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Calibrating Meters in a hybrid studio

Forgive some basic questions but I would like to hear this being explained like I was just starting out.

I assume the analog gear I bought is calibrated correctly but matching the levels between all my analog equipment (converters, summing amps and processors) needs to be matched so everything flows openly and sounds the best is can. Yes and why?

Now that I have converters with greater gain staging input and output control ( +24, +19, +13, +4.2) everything is more precise so I would appreciate critical detail on how to get the best out of my system.
If you walked into my studio what are the steps you take to calibrate everything?

Other than using a screwdriver to adjust the needle on a VU meter back in the 70's, I've never formally calibrated a studio with analog gear like I have now. In fact, I've never even used a multimeter for anything other than testing cable connections.
To calibrate your gear, this is what I read:

Get a multimeter. Okay, what kind of multimeter? Analog, Digital, or! is there a plugin for Sequoia?

Send a 1k tone out of my audio interface
stick my multimeter on the output cable
Adjust level until i get 1.23v on my multimeter
plug cable into device, adjust meter to 0dB


RemyRAD Fri, 01/06/2012 - 21:54

Chris, all professional equipment with VU meters are generally calibrated for +4 DBM into a 600 ohm load. And that equipment generally is specified that its maximum output level is capable of +24/+28/+30 depending on the equipment and output transformers utilized. VU meters are just average level devices and every engineer knows that if they are averaging around -6 to -12, your peak program content is at least +15 DB above that even though the VU meters will never indicate that. PPM meters, popular on British equipment and in Europe are calibrated more like digital meters where peak 0 (zero) may well be +24 DBM or 28, or 30. And those VU meter calibrations should not be messed with nor varied except to check their calibration with a 600 ohm resistor on the output for 1.25 V which equates to +4 DBM.

Now the input to your digital stuff is of course different. So if you really want to calibrate something, I would say apply a 1 kHz sine wave to your analog audio gear. Crank up the output to +24 across a 600 ohm load (The actual voltage value has escaped my 56-year-old synapses, sorry. If I could only find my Ballantine DB to voltage slide rule?). Then turn up the input to your digital audio interface until that 1 kHz sine wave sits at 0 (zero) DBFass (DBFS). And voilà, you are calibrated. But of course if the output of your audio device (such as the API which has 3 secondary windings to allow all three of those standards) is that +28 or, +30, you'll want to calibrate that accordingly to 0 DBFS. For instance, on the output of my 3124 API's, the microphone preamp XLR output is connected to 2 of the secondary output windings yielding headroom to +28. While the 1/4 inch outputs are on a single secondary winding yielding only +24 output capability. Ha! Only +24. And I will indicate that no Avid/Digi crap can handle a +24 line level input without clipping everything at the input even if the pad is engaged. And that's proprietary? Proprietary what? Proprietary incompetence I think? So that piece of crap won't interface with my Neve without an in-line resistive pad. But my $80 EdiRol, UA-1 EX, has no problems handling a +24 output from the Neve on its RCA unbalanced inputs. And there is nothing proprietary there so it works well. Even the MOTU 2408 doesn't like to see much anything over +20 and there are no input sensitivity controls to adjust that. I simply refuse to install 4 DB balanced input pads on its 8 inputs. So I have to be a tiny bit more conservative when I feed it from the Neve. But the M-Blotch 2 is just a no can do from the direct Neve outputs. And they don't want to supply me with a schematic so I can fix it. So screw them. Although I will probably end up with Pro Fools 9 or 10 in the not-too-distant future? Maybe then, I'll start to use it more often? I mean even my M-Audio Transit seems to be able to handle a higher input level than the M-Blotch 2. WTF is with that? Even talking to those Avid Fools in person at the AES was absolutely no help whatsoever. There is nothing professional about that.

I guess I'll stop now?
Mx. Remy Ann David



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