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Uses of expanders

Would someone kinldly tell me the uses/ applications of expanders?


Kapt.Krunch Wed, 05/30/2007 - 17:54
Basically, it's the opposite of a compressor...basically.

If something is squashed, you may be able to bring some of it back to life, within reason. It's not a magic pill. If the waveform is clipped, it won't make it less clipped. There may be a way to do a certain expansion program that will leave the peaks alone, but lower the lower parts. If that's not available, you may have to lower the overall signal, and then expand to bring the peaks up.

Here's what I used one on just recently:

A guy who works for a local, lower power AM station is the midnight Saturday Funk DJ. He wanted to replay an interview that had been previously recorded that he burned to a CD. The thing was nearly wall-to-wall, straight across squashed compression, at a high level. YIKES!

He actually brought the CD to a friend who spent HOURS trying to get it to sound better, but couldn't.

My friend asked how we could make it do ANYthing even remotely listenable. I asked if he tried to expand it a bit. "Expand?"

So, I showed him where in his Cool Edit, you could go into the Dynamics Processing section, and choose to Expand it. So we tried a couple different things, and finally got it to where it had enough dynamics that he could go in and take care of the worst parts by either using some surgical cutting, reducing the volume in tiny places, whatever. He could actually see the parts better, then, and zero in on them, and being all just conversation, had some wasn't gonna futz up any music.

By the time he finished, it sounded much better, and the funk dude was happy he could air it. We didn't expand it TOO much, just enough to work on, knowing it was just going to get compressed to death again anyway when it went though their chain. We didn't want it pumping on him.

When I explained to funk dude what had happened, he said he would relay that to the guy in charge of setting up the program recording/dubbing and tell him to maybe try something different with compression going into the recorder (whatever it is...funk dude is not technical and couldn't tell us) and watch the levels.
I realize a lot of broadcasts are compressed to death, but there's no reason that should have been that bad. It was pretty ugly sounding.

Anyway, there's one use for expansion. Now that my friend found that, he said he's going to try a small amount to see what it does to some of those old LPs that he's converting to digital whose grooves are so narrow they have no dynamics. I suggested that's OK, just do it BEFORE you do any noise reduction.

I'm sure there's other uses, as well, though I've never used it in multi-track recording.

I'm sure someone has stories about "companders" (compressor-expander), and what that was used for?

Anyway, it's bascially the opposite of compression...basically.