AW: Noise reduction

[Haible Juergen]

	>I built a true stereo chorus box for my home brew polysynth a
little while
	>ago. Now I do like the sound it gives but since it uses BBD devices
TDA1022
	>it is fairly noisy. Have any of you had any success in using
companding
	>units, NE570s and the like, to make the outputs quieter? 

The 570 is used in many commercial BBD devices, so ...
The drawback is that it has a rather slow attack time,
at least in its standard application. And, you should use an
external opamp, because the internal one is "741 quality".
Have you looked at Phillips' web pages? Maybe they have
the app notes online ?

If you want to build a noise reduction without special chips,
I may suggest the one I have used in my frequency shifter.
It's almost directly taken from Roland's Vocoder Plus, and
it works nicely.

	>Are you sure none of you know what through zero means?

>From plus to minus (;->).

JH.