[linux-audio-user] sounblaster live platinum and full-duplex recording (noisy)

John Check j4strngs at bitless.net
Mon Aug 16 18:45:12 EDT 2004


On Monday 16 August 2004 02:33 am, Erik Steffl wrote:
> John Check wrote:
> > On Friday 13 August 2004 11:30 pm, Erik Steffl wrote:
> >>   recording seems to be working OK but:
> >>
> >>   in audacity when I record the track it sounds OK
> >>
> >>   however if I generate click track and record then (the click track is
> >>playing while I am recording) the recording is really bad (noisy, low
> >>quality).
> >>
> >>   I vaguely remember something about full-duplex on sounblaster not
> >>being very good, i.e. there's something wrong when using it but don't
> >>remember what (bitrate being forced to be very low or something along
> >>those lines).
> >
> > Which soundblaster?  The "original" ISA soundblasters were like that, and
> > the "soundblaster PCI" cards with the ens1371 chipset have asymmetric
> > sample rates for playback/capture, but I can overdub with my SBLive
> > platinum and it sounds normal.
>
>    I don't remember what I read exactly (and google didn't help) and
> which card exactly it applied to. I have soundblaster live! platinum
> (with live drive). What software do you use? Anything specific that I
> need to set?
>

I haven't had to do anything special, but the last time I overdubbed a day or 
two ago, I had the playback channels both frozen and muted, so I don't know 
if I'm missing something about the problem as described by whoever had the 
details.

> >>   However I can't find any information on that subject now (I tried
> >>google and creative site), does anybody know details and/or have some
> >>pointers to relevant docs?
> >>
> >>   system: debian unstable, 2.6.5 kenrel (with alsa), sounblaster live
> >>platinum (with live drive).
> >
> > How do you have the mixer set up?
> > Which input are you recording from?
> > What mixer app are you using?
>
>    Line LiveDrive, Line LiveDrive Capture,
>    Line2 LiveDrive 1, Line2 LiveDrive Capture 1
>
>    are all the way up, guitar pod (line6) is connected to two rca
> connectors on the live drive. However I was recording mono only (in
> audacity) so I guess only one of them was recorded.
>

OK my livedrive is a early revision and the RCA's are S/PDIF,
but I use the 1/4" line/mic in. Set to line it's stereo
Line-Livedrive (record ready - set to unity). It's associated capture
fader is also set to unity. Capture (main) is record ready and at 0

Things that cause distortion/phase cancellation/"howlround" (feedback with 
british EQ ;):
Bringing up the main capture fader unnecessarily
Bringing up either of the AC97 faders

>    when recording only (no playback at the same time) the recording is
> OK, when I play click track at the same time the recording is very bad.
>

Where is the click routed?

>    I was recording at 44kHz, thought that might be a problem so I
> switched to 48kHz but then there's no full-duplex at all (i.e. the
> already recorded stuff does not play when I record).
>
>    is this a problem of my setup or audacity? (I can't get muse working,

Well, something to keep in mind is when you add a track the output is summed,
so you might have plenty of headroom until you add the click. 
I've noticed a tendency for the SBLive sound to start sucking hard once it's 
had a few transients bashed into the ceiling. I could be wrong as to the 
particular case, but you should be knocking 3dB off of the source track level 
for every track you add to account for the summing when you overdub.
IOW 0dB to the master for 1 track, -3dB to master for 2 tracks, etc.

> it hangs whenever (trace reveals it's reading from some pipe) I try to
> save (which is required to create audio track)). Any other simple
> recording programs (that would make it possible to play the previously
> recorded audio (aka full-duplex aka overdubbing)?
>

Depends on what you call simple. If you were trying MusE, I'll suggest 
Rosegarden4. I like Audacity, but the lack of metering really doesn't make it 
suitable for recording. 

> 	erik



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