Using Pink Noise to calibrate AD/DA?

[A27Hull]

Well, for A/D,

my thoughts were to run a pink noise gen from PT (I have no outboard signal gen or RTA,) set the internal PT level to correspond to .775 V at the analog outputs outputs using a voltmeter. Thus, I would be making a +4dBu reference level to feed the PSX.

I'd then calibrate the PSX to -20dBfs using this signal.

Where am I screwing this up? Is it my hazy understanding of calibration?

I'd use the same internal level that I referenced to +4dBu, but change the output to s/pdif, using the s/pdif inputs on the PSX to calibrate teh D/A.

Why white noise?

[A27Hull]

thanks

[barefoot]

Noise is fine, but I also don't see any reason not to use a pure tone for calibrating AD/DA. Broadband noise helps average out the kind narrow frequency response variations you get within and between speakers. But your converters will almost certainly be quite flat within their bandwidth and won't fluctuate by more than a small fraction of a dB. So assuming your meter gives you accurate reproducible readings at whatever frequency you use (say 1kHz), then a pure tone should be just as good.

Thomas

[A27Hull]

thanks

[Jim Williams]

Use a tone. Noise is random by it's nature and isn't steady state enough.

Jim Williams
Audio Upgrades

[bulli]

i agree use a tone. 1k - the techs favorite music.
it will be difficult to get an accurate reading with the noise bouncing around and with converters we tend to get pretty picky like .1db picky.

[A27Hull]

yes

thank you!

[A27Hull]

So, (today)

I set the gen at 1 Khz, calibrated the PT analog output signal to 1.228 V. I guesss this would be my +4dBu reference.

I fed that signal to the AD input, and calibrated the AD section to -20dBfs. on the PSX, (lowest possible LED).

Then I re-routed the same calibrated signal (in PT) to the S/PDIF output, and sequentially to the PSX S/PDIF input, thus sending the same calibrated signal of the AD section to the input of the DA section of the PSX.

I then used the meter to measure the output of the DA section, and trimmed the output until the meter read 1.228 V.

Is this correct?

[A27Hull]

bump-