Anlogue output levels

[Music Manic]

I'm just testing my setup and I've setup an analogue (RCA) out to in loop to record the signal. My question is what is the output level converted to by the A/D? Is it a line level 0dBvu out. -18dBfs so to speak?

Thanks

[Bud Weiser]

AFAIK,- w/ the Classic20 plate and RCA it should be line level -10 dB and w/ the "Plus" (XLR) plate it should be +4dB.



Bud

[valis]

This is correct. Dbfs is a measurement in the digital realm and shouldn't be applied to analog levels.

[Music Manic]

This is correct. Dbfs is a measurement in the digital realm and shouldn't be applied to analog levels.

I understand that. My question is the output level at the D/A stage which means there has to be a voltage level. Recording the output back into the analogue input shows the drop in level which means it was more likely a -10dBv output as suggested above.

[valis]

My point was that we’re dealing with two different scales in the analog realm plus a digital scale (dBf plus dBu being "dB - un weighted" and dbV - dbVolts", and dBu can be used regardless of impedance, but is derived from a 600 Ω load dissipating 0 dBm (1 mW) ).

Typically the output voltage isn’t directly calibrated against -18 dBfs, and line level (-10 dbV) should typically always be reference to 0db = .775volts. So the resulting difference between +4dBu and -10dBV is about 11.79dB [based on a logarithmic scale so its not a straight 14]... which was originally done to reduce the noise level in "semi pro" equipment (higher amplitude signal in, less noise... also less headroom and a whole bunch of other issues that TC Electronics did a nice white paper on some years ago).

Hope this is of some help in clarifying, sorry for brevity of response before.

[Music Manic]

Sure Valis. My test is the signal from the DAW which I’d dBfs to the analogue out looped backed to the analogue in back into the DAW. The signal reads much lower on the dBfs scale which means the conversion by the scope D/A RCA outs is in the realm of -10dBv. When I test the XLR loop back signal it should be much higher.

Just a test to understand gain structures of my system.

[valis]

If you're looping out of the RCA out, directly back to the RCA in, you should not be seeing a ~10dBf drop in levels. This large of a gain change will only occur when going through devices that have different signalling levels (presuming no DI box or etc is being used inline to compensate for this impedance & level difference).


Are you connecting directly to the i/o modules, or are you going through a device before going to the output?

[Music Manic]

If you're looping out of the RCA out, directly back to the RCA in, you should not be seeing a ~10dBf drop in levels. This large of a gain change will only occur when going through devices that have different signalling levels (presuming no DI box or etc is being used inline to compensate for this impedance & level difference).


Are you connecting directly to the i/o modules, or are you going through a device before going to the output?

Signal generator from DAW -> ASIO out -> Pulsar Analogue out -> Pulsar Analogue In -> ASIO in -> DAW channel.

Nothing In between Valis. I will take a screen shot to show you today.

[valis]

Sure, include both DAW and Scope please, so I can see any relevant mixer & master info. Also show it with the test signal.

[Music Manic]

Sure, include both DAW and Scope please, so I can see any relevant mixer & master info. Also show it with the test signal.

My Apologies Valis. I’ve just checked it and the signal comes back in at just -0.1 dB lower with one millisecond delay so the level drop is not noticeable at all and the gain level is great.

After 20 years these boards still give me pleasure.

Thanks for your time but more questions coming