Quote:
Otto wrote:
 Hi Blue,
Oh, I thought you had already calibrated it with an analog loopback. I don't think it's possible to properly calibrate your soundcard using the digital I/O because you'll be using analog input when you do your measurement (because the input signal be coming from an analog mic). |
But I am using an analogue input to the soundcard (digital out from soundcard to receiver, analogue out from receiver to analogue line-in on soundcard) when doing the loopback. The only difference that I can see is that rather than converting the signal from digital to analogue in the soundcard (then feeding it back in analogue into the soundcard), I'm converting the signal in the receiver (then feeding it back in analogue into the soundcard). I have compared the two responses (soundcard only loopback vs. soundcard-receiver-soundcard loopback) and can see that the drop-off is less when the receiver is in the loop (presumably due to the superior DA conversion), compared to the soundcard only.
Anyway, if that's not correct. Would it be better to do the conventional soundcard only loopback to calibrate the card, then use the soundcard's analogue output to the receiver (which then passes the signal to the sub) when doing sub measurements? Alternatively, should/can I calibrate the soundcard conventionally (no receiver), then use the digital out from the soundcard to the receiver (which converts it to analogue for the sub) when measuring the sub? However, won't the latter method give false readings due to the difference in drop-off to the sub between the soundcard's analogue output (via the receiver), used in calibration, and the soundcard's digital output (converted to analogue in the receiver), used in subsequent measurements? I know you did say Otto that you compared the outputs and found them the same but maybe my soundcard/receiver outputs are different to yours? So should I just use analogue throughout for setup calibration and subsequent measurements (analogue soundcard-receiver, analogue receiver-sub) and be done with it?
Cheers,
Blue