How to adjust relative gain when recording in stereo?

[Peter S]

I'm new to Audacity. Can any of you boffins out there offer any advice on this pl?

I plan to transfer some of my old cassette and vinyl recordings to CD. One old tape has a low recorded volume level on the right channel relative to the left. I'd like to restore it to a proper stereo balance when I transfer it to CD.

If I were re-recording it on a conventional cassette deck, I would simply increase the gain level on the R/H channel until I got a satisfactory stereo balance. But Audacity provides only one slider control for the input level on both channels. There's a gain slider beside each of the stereo tracks (when you split them), but this only affects playback as far as I can see.

Help/advice much appreciated!

[waxcylinder]

I don't think you can do this while recording with Audacity. However once you have made the recording you can Split Stereo Track (use the drop-down from the downward pointing triangle in the track control box). This will give you two separate mono tracks thta you can manipulate separately. Select the track with the low recording level and use the Effect>Amplify command to get a suitable level to match your other track.

Then select both tracks and use the the Make Stero Track - only available from the trianngle drop-down in the top track of the two.

Or I suppose you could be fiendishly clever and do the recording twice - one with levels set for the strong-levelled track - and the second with levels set for the weak-levelled track to record at a suitable level(which will of course cause serious clipping in the other track). Use the Split tstereo track on both recordings, delete the two tracks you don't want - then bring the two tracks together in the samne project with a bit of cut and paste. Your biggest problem will be to get the two tracks exactly lined up - zooming in will help. Then combine these as a stereo track.

But I'd certainly try the first option and test the result - please post back and let us know how you get on with this.

WC

[steve]

The best way is to adjust the levels that you are recording.
Depending on your soundcard drivers, it may be possible to pan the input signal in the recording section of your soundcard mixer so that when you record, both tracks sound (and meter) the same level.

If your mixer can not do that, some hi-fi amplifiers have an output that is connected after the pre-amp section and before the power amp. If you connected your tape player to the amplifier, then connected that output to your computer, you could use the amplifier balance control.

Failing both of these methods, you can split the track as described by WC.

There are alternative ways to re-combine the left and right channels. I find that the easiest method is to do nothing (leave them as separate tracks) - when you Export the audio at the end, it is automatically mixed into a single stereo file.
(you can also use the "Quick Mix" in the "Project" menu).

[Peter S]

Thanks for your quick and helpful responses.

The Preferences->Amplify approach suggested by Waxy seemed the simplest. I tried it and it worked quite well.

I had to make a couple of attempts to get it right. It’s necessary to guess how many decibels to boost the offending channel, record it, listen to it, then try again with a lower or higher db until it sounds right. Not as easy as being able to adjust the input volume independently on each channel.

Maybe a future release of Audacity should have twin gain controls for stereo recording? Still, mustn’t whinge – it’s free after all. What it does, it does well.

Thanks.

Peter

[steve]

The Preferences->Amplify approach suggested by Waxy seemed the simplest.

Yes that is probably the simplest, but you will get better quality if you record a signal at the correct level, rather than correcting the error after you have recorded it.

It’s necessary to guess how many decibels to boost the offending channel, record it, listen to it, then try again with a lower or higher db until it sounds right.

You can use "Normalise" on each channel to bring them up to 0dB (or any other level).

Not as easy as being able to adjust the input volume independently on each channel.

You CAN adjust them independently - you just "Split Stereo Track" first as described bu WC.

[Peter S]

Thanks stevethefiddle.

You will get better quality if you record a signal at the correct level, rather than correcting the error after you have recorded it.

Agreed - "garbage in, garbage out!".

You can use "Normalise" on each channel to bring them up to 0dB (or any other level).

Thanks for tip. I've used this on subsequent recordings. (Except that the dialogue box seems to offer only a fixed -3db?)

You CAN adjust them independently - you just "Split Stereo Track" first as described bu WC.

But this still doesn't give me 2 slider gain controls - one for each channel. Am I missing something? (Bear in mind that I hadn't even heard of Audacity until a couple of weeks ago!)

[steve]

Thanks for tip. I've used this on subsequent recordings. (Except that the dialogue box seems to offer only a fixed -3db?)

You should be able to type a number in the box. (note that the maximum level should always be a negative number. I'd suggest that you try -0.1 dB)

But this still doesn't give me 2 slider gain controls - one for each channel.

When you split a stereo track, you get two completely independent mono tracks, one assigned to the left channel, and one assigned to the right.

[morvenwestfield]

I'm a complete newbie here, so I apologize if this is obvious.

I just recorded a Skype conversation using MX Skype Recorder and it went well. Thanks to the excellent suggestion in this thread about splitting a stereo track in two, I now have the right channel (me) and the left channel (the person I called) separate. This is great because I plan to use this in a podcast and I know that as a podcast listener, nothing drives me more crazy than one person being a lot louder than the other.

The two tracks are close enough in volume that I can leave them at is, but I want to learn how to tweak it if I need to. I'm just slightly softer than the other person. I tried selecting his track and then choosing Effect > Amplify, but from there I'm lost. When I enter a number or slide the slider on the Amplify dialog box, the OK button goes grey (become available), so I can't apply my changes.

Any suggestions? I looked in the help and Wiki and didn't find anything.

Thanks,
Morven


http://www.morvenwestfield.com
http://www.myspace.com/morvenwestfield

[steve]

I tried selecting his track and then choosing Effect > Amplify, but from there I'm lost. When I enter a number or slide the slider on the Amplify dialog box, the OK button goes grey (become available), so I can't apply my changes.

I think you mean "become unavailable". This is because you are trying to amplify the track too much. If Audacity did the amplification at the level you have set, then it will cause the audio to "clip" (distort) and will sound horrible.
Select the other (louder) track and reduce the volume (apply negative amplification)

[morvenwestfield]

Yes, you're right -- I did mean unavailable.

After I posted my message, I continued looking for information and found this thread, which seems to be similar to what you're saying:

http://www.audacityteam.org/forum/viewt ... ify#p13692

I also didn't realize what db (decibles) really implied, so now it makes a lot more sense.

Thanks!