Two questions.

[uncleape]

When I mixdown all of my tracks, with CoolEdit, into one, the mixdown, some of the audio gets distorted. All of the tracks are perfectly clear until I mix them down, and at many of the louder points the audio distorts. Can anyone tell me what is causing this and how to fix it?
Also, can anyone give me some quick tips on using compression or other "amplitude" tools to help out with ear fatigue? I appreciate any replies. Thanks.

 

[uncleape]

And one more: in the piano track the piano pedal makes an undesireable squeak. Could anyone tell me how to isolate this sound and remove it without damaging the rest of the track?

 

[lpdeluxe]

The distortion is appearing because at some point the summed tracks are going over digital 0 on the meters. This happened to me early in the process of mixing a CD where I had two female vocalists singing together on separate, overdubbed tracks. I re-EQd one of the tracks so there was less frequency overlap and the distortion disappeared...but it was quite a job isolating exactly where it was coming from! That ended my early attempts to apply my tape chops to digital: after that I didn't try to "knock it against the red" when recording and rolled back the levels.

As to the squeak, a couple of releases later (Adobe Audition 1.5), a lasso tool was introduced where you could draw around the noise while in the frequency spectrum mode, and click on "Fix Click Once." This is really useful...but there's no equivalent in CEP, as I learned while trying to reduce finger squeaks on an acoustic guitar recording. Avoid compressing the piano track: that makes noise like pedal squeaks jump out. If you've already found that out BECAUSE OF compressing, there's no way back that I know of, once you've saved the session/track.

 

[uncleape]

What is the digital 0? Can I simply lower the level of all of the tracks uniformly to solve the issue? Thanks.

 

[sikter]

What is the digital 0? Can I simply lower the level of all of the tracks uniformly to solve the issue? Thanks.

Yes you can. In newer versions you can easily turn down master output volume.
If it accures on some spots only you could use volume envelopes to turn down volume only on that part.
(In newer versions yo could use automation)
It is often one track only which makes mix go over 0 dB.

 

[lpdeluxe]

When you look at the wave form of your stereo mixdown in Edit View, you'll see that there is a dB scale at the edge of the display. It shows excursions upward and downward, and the scale near the top and bottom are "0" -- the point beyond which you get digital distortion.

There are several ways to deal with "overs" -- instances where the summed tracks cause the amplitude to exceed 0 dB -- and the quickest way is to go to "Effects/Amplitude/Normalize." Click on that and a window comes up with a highlighted numeric field: set that to "0" and apply it. This will set the highest point in the track to 0 dB, and that may fix your distortion.

If distortion remains, that means that the distortion is on one or more of the tracks, and you'll have to look at each one in Edit View to see which ones have gone over 0. You can "normalize" individual tracks prior to mixdown, but for various reasons it's better to avoid that.

You can also apply compression, but you really should confine the use of compression to situations when you want that effect on the mix, and not just as a cure-all, since it will change the overall sound.