2010/2/17 Lennart Poettering mznyfn@0pointer.de
Hmm, so you basically tuned the USB card's DAC/ADC level to the HDA card's DAC/ADC.
I now measured the "Master" slider of my aureon (USB 0ccd:0028, TerraTec Aureon 5.1 MkII) with the aforementioned dbmeasure tool and a loopback cable. The aureon has 65536 volume steps, but I was too lazy to measure them all. So I only measured every 3000th. From the max volume to the min volume:
65536 0 dB 62536 0.00560039 dB 59536 0.00694678 dB 56536 0.00616732 dB 53536 0.00645077 dB 50536 0.00673421 dB 47536 -1.49514 dB 44536 -1.49455 dB 41536 -1.49648 dB 38536 -2.98666 dB 35536 -2.98486 dB 32536 -2.98536 dB 29536 -4.48688 dB 26536 -6.00084 dB 23536 -5.99928 dB 20536 -9.00246 dB 17536 -10.5425 dB 14536 -16.5274 dB 11536 -32.9435 dB 8536 -43.4326 dB 5536 -43.5066 dB 2536 -43.2968 dB 0 -43.4431 dB
If you plot this it looks as if the card actually only implements 10 or so discrete steps, and at around 10000 just becomes a constant function.
ALSA reports -47.87 .. -1.97 for this. So it seems the overall range the USB data reports is not really that far off, but the volume function in bteween is.
The noise level of these measurements is < -58 dB.
What's the next step with this measurement data? Will you take it from here, or shall I provide you with more data?
Lennart
How about dbmeasure the pulse device since the volume control seem also have 65536 step ?
Can you provide the result for the pulse device ?