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splicing mixer channels
Posted: Tue Jan 19, 2010 8:09 pm
by cryingfist
Hi,
I'd like to know if it's possible to accomplish the following feat:
I run audacity on an acer 5920g with windows vista and a realtek alc888/1200 integrated audio card with two inputs (mic and line in) and one output. I've got an hardware mixer with four microphone channels (canon-xlr) and i plug it into my computer microphone input via a minijack cable (actually it's a stereo double jack to single minijack cable which exits from the mixer's stereo output and goes to the computer microphone input). Is it possible to actually splice the signal arriving to the computer in order to record separately the four microphones channel?
i.e.: is it possible, if we are singing using channel 1 and 2, that audacity recs two separate tracks, one recording channel 1 and the other recording channel 2?
Probably my statements are not very clear: I beg your pardon, I'm italian and an "audio-noob"
I'm also afraid that the answer to this question is "no way", but at least i've got a qualified answer and not a "noob guess"

Re: splicing mixer channels
Posted: Tue Jan 19, 2010 8:45 pm
by steve
With a bit of trickery you can record 2 channels, but not 4 channels.
cryingfist wrote:realtek alc888/1200 integrated audio card with two inputs (mic and line in)
You should use the "Line in" and not the "Mic in".
The Mic channel is for directly connection a microphone, but as you are using a mixer, your microphones will already be amplified and will overload the Mic input on the computer. Also, Mic inputs are often mono and have a voltage on one of the connections for powering computer microphones.
Most mixers have the option to "pan" the input to the right or to the left.
The trick is that the sounds that you want on "track 1" in Audacity should be panned to the left and sounds that you want on "track 2" should be panned to the right.
Now set Audacity to record a stereo track. When you play it back you should hear that some sounds are on the right and some on the left.
Now click on the name of the track and from the drop down menu select "Split Stereo to Mono". You now have 2 mono tracks. Track 1 will have the sounds that were on the left and track 2 will have the sounds that were panned to the right.
Re: splicing mixer channels
Posted: Tue Jan 19, 2010 9:29 pm
by cryingfist
thank you! your post is enlightening

Re: splicing mixer channels
Posted: Thu Jan 21, 2010 8:12 pm
by cryingfist
another question, that dawned on my today: is it possible, since i've used the mic in, that the mic in voltage could have damaged the microphones and/or the mixer?
Re: splicing mixer channels
Posted: Thu Jan 21, 2010 8:35 pm
by steve
It is certainly not a good thing to do, but I think that it is fairly unlikely to cause real harm. There should be current limiting on the microphone voltage to prevent it from blowing anything up. Why do you ask? Is there a problem?
Re: splicing mixer channels
Posted: Thu Jan 21, 2010 9:20 pm
by cryingfist
When i used the mixer everything worked fine...I mean the computer recorded regularly the songs we played, nothing fizzled or sizzled or burned. The tracks recorded sound fine (at least for what i can say).
But i also made recordings without using a mixer: i (stupidly) plugged my microphone (a shure pg48) into the mic input using a canon-xlr to jack cable (adapted through a jack to minijack adapter) and i hear i whistle when i record songs this way. But this whistle is present also if i use the line in.
This whistle it's not present in the tracks recorded through the mixer, which, instead seem very clear.
So my hope is that the whistle comes from the crappy combination of cable and adapter (since i used the same mic when recording through the mixer and the whistle was not present).
I repeat, the track recorded through the mixer sound fine and during the mixer recording session there were no "strange" electrical activity (at, least for what i recall)
...please tell me that i've not blown up everything...

Re: splicing mixer channels
Posted: Fri Jan 22, 2010 2:54 am
by steve
cryingfist wrote:...please tell me that i've not blown up everything...
I don't think that you've blown anything, I think that you are just experiencing the true (bad) quality of the built-in sound card. If you'd blown something it would most probably not work at all.
Are we talking about a laptop computer or a full size desktop computer?
Does your sound card have a "Line input" AND a "Mic input", or just one input socket?
(on-board sound cards are generally designed to give "acceptable" sound quality for Skype, playing music through computer speakers, and that sort of thing. They are not designed for high quality recording.)
Re: splicing mixer channels
Posted: Fri Jan 22, 2010 7:56 am
by cryingfist
we're talking about a laptop computer: an Acer5920g with an Intel Realtek soundcard with both a line input (a blue coloured 3,5" minijack) and a mic input (a pink coloured 3,5" minijack) (and an earphones output, a black coloured 3,5" minijack)