Track dynamic range

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nmoffitt
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Joined: 2011-02-07
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I have recently gotten Ardour working on my Ubuntu Studio workstation, after using Audacity for several years. The only problem I have is that I am unable to fully utilize the dynamic range of my tracks. I have a mixing board feeding a PCI SoundBlaster card through the Line input. It works, but I cannot seem to record at a level higher than roughly -8 dB. When I try raising the mixer output, it just starts clipping even though it looks like I have all of that headroom.

To rule out the mixer/sound card/Ubuntu, I tried recording in Audacity and I am able to saturate both channels (if I wanted to!) This leads me to believe that the problem is somewhere between JACK and Ardour, or perhaps in the ALSA handoff to JACK. Could anyone point me to the setting(s) I can look at or suggest another approach?

Many thanks!

peder
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Joined: 2007-05-08
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For starters a SB card probably won't give you any hi-fidelity anyways (see for example http://www.pcmus.com/choosecard.htm#whynot) so -8 or -0.3 dB probably won't make much of a difference.

I don't think JACK has any knowledge of sound volume in itself, it's more or less a patchbay, so I'd start with checking the ALSA levels in alsamixer.
And what happens if you take the saturated Audacity sound and import it into Ardour. Is it still saturated or does Audacity just display the levels differently?

nmoffitt
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Joined: 2011-02-07
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Thanks for the response! I was able to expand my ceiling in alsamixer like you said. It was the AC97 gain setting, which I thought was odd because it's the symptom is more like a limiter than a gain setting.

I suspect this reinforces your tip on SB cards - I'm probably just raising the ceiling by adding noise (raising the floor with it). In any case, I learned a bit more and I'm probably going to go sound card shopping. Thanks again!