L/R Channel Imbalance

[kozikowski]

The strong suggestion at the beginning of this was that all the presentations had one low channel over multiple records. We shouldn't read any more into this than there is. If this was an analog system, you would be turning the low knob up slightly and leave it there forever -- or cocking the balance knob slightly -- also forever. In the case of the balance knob, the result would be instant and observable and not a result of further tools.

This could be a minor equipment problem easily solvable by a simple boost of the low one, or lowering of the high one. I would still not be doing this automatically. There are too many chances of the software trying to "help you" and actually making things worse.

Koz

[patcurci]

The strong suggestion at the beginning of this was that all the presentations had one low channel over multiple records.

Kos is correct here, and the balance knob on the amplifier would solve the problem. Again, this condition is only seen via the recording meter in Audacithy and my interpretation. I'd still like to make the best possible quality CD as true to the original LP as possible. So, adjusting the "balance" via software, before making a CD, seems to make sense.

Subtle difference between Amplify and Normalize

If I understand one of the differences between these 2 effects-------------

With a joined stereo track:

Amplify will increase the volume of both L & R tracks equally to the point that the maximum peak of either track will just be clipped.

Normalize will increase the volume of both the L & R tracks so that the maximum peak of each track will just be clipped. Normalize could actually increase either the L or R track in unequal amounts and more than intended by the original recording engineer.

Did I get this right?

Regards, Pat

[kozikowski]

Almost. Neither tool will cause clipping damage unless you specifically tell it to. Damage only occurs if the music peaks go over 0dB -- and even then if you're not in the 32-bit floating mode which can survive that.

There was a spirited discussion a while back whether to consider Normalize "Damage" or not since it could easily throw off the intended balance of the show. I call that damage and I only use Normalize to get the DC removal tools, which IMHO are superior to other methods and nobody has offered evidence that it's not.

Other software products fold Normalize and Amplify into one tool with option clickies whether or not you want the two channels linked.

Koz

[patcurci]

Koz:

Thanks for the reply. I did mis-speak (write) when I implied that there actually was clipping. I know there isn't unless you tell Amplify to "allow" it. But my understanding is correct then----these tools work with "peaks" as limiting factors rather than some kind of average or compilation.

I don't think I need to know the technical explination but what to expect in general terms. And I thnk I have that now.

Your recommendation to split the tracks, amplify the low one by some factor (you suggested 3db, although that sounds like a lot for the 5% imbalance that i estimate) and then re-join the tracks, seems the best approach to keep to the original recording as best as possible.

Many thanks.

Regards, Pat

[steve]

these tools work with "peaks" as limiting factors rather than some kind of average or compilation.

Yes, spot on.

to split the tracks, amplify the low one by some factor (you suggested 3db, although that sounds like a lot for the 5% imbalance that i estimate) and then re-join the tracks,

It's a lot quicker and easier to just nudge the pan slider over a bit. Try it on a couple of tracks and see what you think. As you are unsure of exactly how much to pan, try a few different settings on small sections of the track, (Ctrl+Z to Undo), then apply to the whole track the setting that sounds best.

[waxcylinder]

It's a lot quicker and easier to just nudge the pan slider over a bit.

My personal preference is still to get the hardware set-up properly balanced so that both stereo channels are delivering an "equal" signal to the soundcard - obviating the need for any further balancing in software.

After all, that is how the hardware is supposed to work. If it doesn't, there is a fault somewhere: misaligned cartridge, poor/dirty connections, un-balanced amp/pre-amp etc. - so ideally it is better to sort that out properly.

WC

[steve]

My personal preference is still to get the hardware set-up properly balanced so that both stereo channels are delivering an "equal" signal to the soundcard - obviating the need for any further balancing in software.

I totally agree, but for dealing with existing Audacity recordings the pan slider would be a good tool to use.

[patcurci]

stevethefiddle:

I'll play with the pan tool as you suggest. I always appreciate your advice.

waxcylinder:

After all, that is how the hardware is supposed to work. If it doesn't, there is a fault somewhere: misaligned cartridge, poor/dirty connections, un-balanced amp/pre-amp etc. - so ideally it is better to sort that out properly

.

No argument from me, but with the turntable just back from professional service (with the "imbalance" problem on the list) the service folks (who I trust) said all is well in this area. So the problem lies with the preamp or someplace within the computer. If you review my original post, and note stevethefiddle's comment about occasional "unreliable meters" the problem just may be in my head, er........That's wrong, since I can't hear the imbalance, only see it via the meters. My eyes tell me so So the problem may still be in my head?

But I do appreciate the advice. Thanks all.

Regards, Pat

[kozikowski]

I've been relying on my meters too long to stop.

Did you know the Audacity meters only measure the positive-going waves? I created a test track and noted the meter values. Then I flipped the track polarity and the meters were clearly (in this case) different. They should not have been. One of the specifications in both the BBC-PPM and the ANSI C16.5 VU Meter is the ability to completely ignore polarity.

Ears are notoriously bad at sensing changes in volume. Reduce the volume of a clip by 6dB. That's half the signal. It doesn't sound like you did very much, does it? It's one of the reasons when you upgrade your music system, you have to double the size of the amplifier to notice any improvement. Going from a 30 amplifier to a 40W amplifier -- all things being equal -- is a nearly a complete waste of time.

I wouldn't be shocked to note that you fix your imbalance in post production and fail to notice any difference.

Koz

[patcurci]

Koz:

Now you've gone and done it. There you are being practical.

For the serious audiophile any perceived channel imbalance is something to be tracked down and killed without hesitation. Being the amateur that I am, I guess that's why the very first question of my original post.

In all seriousness though, the discussion was very helpful for me. I'm glad the first question wasn't answered until the last. I understand the Audacity software better and that knowledge will help to make my recordings just a little better in quality.

Even the amateur should strive to do the best possible job.

All the folks on this Forum are a great asset to the Audacity team. You make this endeavor a lot more fun and productive.

Regards, Pat