Level Calibration

Posted: Sat Jul 15, 2006 9:17 am

I am looking for guidance with regards to the calibration process I should use with all my hardware gear (DA, compressor, eq, AD).

What are the standards, how do I measure the output levels, how do I make sure that the level reference point is the same for all boxes?

For instance, my GML compressor is set to receive signals @ +4dBm. A quick search on the web shows that this coresponds to 1,23V RMS. Would you agree with the following calibration process:

- send a pure tone at full scale from my DAW
- measure the voltage between PIN 1 & PIN 2 of the DA output
- set the DA output level so that it corresponds to 1,23V
- loop the DA output to the AD input and make sure to reach 0dBFS

Thanks in advance for your educated response.

Best,
Thomas

Posted: Sat Jul 15, 2006 9:25 am

Quote:

send a pure tone at full scale from my DAW

No, not full scale, set a 1K tone at your operating reference level.
TV and Film use -20dBFS Music uses -18dBFS, others use -14dBFS

When you loop the tone back to the D/A the reading should be one of the above youve used.

Does your DAW have analog output adjustments????
Does it have input adjustments???

There are 2 books I recommend to every one:

The Mixing Engineer's Handbook
by Bobby Owsinski "
Mastering Audio: The Art and the Science
by Bob Katz "

This is the best education anyone can get for under $100.00 USD

Posted: Sat Jul 15, 2006 9:40 am

Thanks for the swift response.

Quote:

Does your DAW have analog output adjustments????
Does it have input adjustments???

No it doesn't as such as it is not tied to any specific hardware (I use SEQUOIA). However, my external convertor (Lavry) have such adjustments. In fact, I can also use the sine generator of the external digital board (DM2000 here).

Could you please confirm the voltage measurement has to be done between Pins 1&2, and not between pins 2&3 (twice the voltage)?

Thanks!

Best,
Thomas

Posted: Sat Jul 15, 2006 9:56 am

Quote:

In fact, I can also use the sine generator of the external digital board (DM2000 here).

The tone should come from the source of the audio playback.

Quote:

Could you please confirm the voltage measurement has to be done between Pins 1&2, and not between pins 1&3 (twice the voltage)?

If you are pin 2 hot:
I believe it was 2 & 3, Im drawing a blank now, your measuring A/C voltage
between + and -, not ground. I cheat and use an XLR to TRS adapter, and measure across tip and sleeve.
1&2 and 1&3 should measure equally 1/2 the voltage each. Yes so it would be the one that has twice the voltage.

Posted: Sat Jul 15, 2006 10:11 am

Quote:

The tone should come from the source of the audio playback.

Agree, but it is all the same in my setup as all tracks are sent in MADI from Sequoia to the DM2000 to the Lavry, so there is not DAAD conversion between the DAW and the dig mixing desk.

Quote:

If you are pin 2 hot:
I believe it was 2 & 3, Im drawing a blank now, your measuring A/C voltage
between + and -, not ground. I cheat and use an XLR to TRS adapter, and measure across tip and sleeve.
1&2 and 1&3 should measure equally 1/2 the voltage each. Yes so it would be the one that has twice the voltage.

Yes, there was a type that I have edited before you sent your latest post. I meant between 2&3. So, just to be crystal clear:

- I send a -18dBFS 1kHz tone from Sequoia or the DM2000
- I adjust the output level so that I read 1,23V between pins 1&2 (rpt 1&2)

What about the AD calibration now?

Thanks!
Thomas

Posted: Sat Jul 15, 2006 10:32 am

Quote:

- I adjust the output level so that I read 1,23V between pins 1&2 (rpt 1&2)

NO, between 2&3 on XLR, I just verified this on my PTHD

Quote:

Agree, but it is all the same in my setup as all tracks are sent in MADI from Sequoia to the DM2000 to the Lavry, so there is not DAAD conversion between the DAW and the dig mixing desk.

The SOURCE of audio should generate the reference tone. Send a tone from the DAW through all digital paths until you reach the D/A. Make your adjustments at the D/A, do you need a -18dBFS file??? To play back from the DAW???

Quote:

What about the AD calibration now?

Thatas a function of input, take the last analog signal, and calibrate the A/D to read -18 in your DAW.

Posted: Sat Jul 15, 2006 10:41 am

Thanks for the educated response. That makes perfect sense. Any idea regarding the other thread on the mastering forum?

Best,
Thomas

This topic sponsored by: