Hi,

I have a batch of WAV files (ripped from vinyl) which have severe stereo imbalance. Sometimes the left channel is much lower than the right, or vice-versa.

Is there any tool available which can bring the (RMS?) level of the lower channel up to that of the higher channel. Ideally, it would be able to do it in batch mode as there are a lot of files.

Any advice would be much appreciated.

Regards,
Jonny

I vote for transfer again and this time pay attention to the process. It will be better than trying to 'fix' it. Nothing ruins audio more than 'fixing' it.

G²

I would support this, but that will require a lot of effort. If the difference is not very high, volume correction of the channels might be a very acceptable solution. Wavegain is able to do that, but you would need to split the separate channels out of the wav first, process the mono files, then recombine the channels.

Take a look at sox, "the Swiss Army knife of audio manipulation". It might be able to split the channels. It cannot calculate replay gain, though.

With SoX v14.1, there's norm -i which might work here -- it normalizes each channel individually. You could use this in a shell/batch file for loop for batch mode.

- bandpass

I used Audacity to correct the balance

if you decide that you need to
a. stereo to 2x mono
b. process each channel
c. 2x mono to stereo

then do some searching on the forum for a. and c.

Thanks for the replies.

I agree that ideally the ripping process should be correct in the first instance. I saw a couple of topics on here where it was suggested that there may be cartridge or preamp problems. These are issues I will look into before ripping any more.

But I don't have the time to re-rip the ones I've already done. I'll take a look at SoX, which I'd never heard of. Thanks for the tip.

Regards,
Jonny

Is it really safe to assume that the channels should have the same peak volume, and isn't that what you will do by normalizing them?

I was hoping to give them the same rms (not peak) level, since they are so far out that clearly the ripping process was flawed.

I have noticed that channel imbalances most of the time are due to technical problems with the recording medium and/or playback equipment.

Many of my tape transfers have a level difference of > 3dB between channels that seems to be due to tape deterioration.

A lot of my well used LP's have a constant level difference too. Here's an example from an unrelated thread Level Difference. The CD levels are pretty even but the the vinyl samples have a decent channel difference.

Laslty, some recordings are meant to have quite big channel level differences. Examples of this are when specific instruments or voices are always on one channel or the other.

Fixing imbalance problems I have used CoolEdit/Audacity channel mixer.

I usually decide if there is imbalance by zooming out to view the waveform for the entire recording. If one channel appears to have lower peaks throughout the entire recording, then I assume the balance needs to be rectified.

I think GoldWave ($45 USD after free trial) has exactly what you are looking for - It has a feature called Max/Match that makes the average left & right levels equal. At the same time, it normalizes (maximizes), so that the channel with the highest peaks (after matching the average levels) has peaks of 0dB. (Because of normalization, the balance-adjustment will never introduce clipping.)

When I use this feature, I usually make one big WAV file for the whole album/recording so that I can retain the original song-to-song level differences.

GoldWave does have "batch processing", but I've never tried it. (Audio editing usually requires human interaction.) If you do batch-process and "max/match" each track individually, you will individually normalize each track and you will loose the original song-to-song dynamics (which may be undesired).

P.S.
It might be possible to make a batch process that combines the tracks, performs the max/match operation, and then re-splits the tracks. Or, you may not care about retaining the song-to-song volume differences... i.e. If you are going to use Replay Gain in the track mode, you will end-up adjusting-out those differences anyway.

The MaxMatch option in GoldWave is indeed exactly what I'm looking for.

Thanks DVDdoug.