AW: Cermet vs plastic pots..

[Haible Juergen]

	>Excellent post!

Kevin's informations are *always* highly useful.  8-)

	>I'm always suspicious to pepole who recommend things on the basis
that they are 
	>more expensive and therefore must be better.
	>/Jorgen

Nevertheless:
Be sure that Paul knows what he does, when he selects components.

Or the people who select position sensors for medical equipment,
for that matter. Never seen a cheap carbon pot in a dentist's chair.  
Imagine the consequences ...  (;->).


Kevin:

	>but the worst and noisiest pots I've encountered in synth
	>restores- Emu modulars- Conductive plastic.
	>They *should* be great. They look great on paper, they are
wonderful when
	>new, but they just don't seem to hold up.

I have to admit that I felt quite save when I chose Bourns conductive
plastic types for my Synthi Clone. 
Did you have any bad experience with Bourns potentiometers, too?
What was the brand used in the Emu Modulars?

General question: There are obviously great differences between
one type of potentiometers, like carbon type, as well. Just think that
most of them scratch along the carbon layer with a piece of metal.
But there are also some that use a piece of graphite (sp?) here, too,
to avoid abrasive effects.

General remark: Tolerance and temperature drift should be a non-issue
in the right circuit design. Use the pots as voltage divider with high-Z
load (and not as variable resistor) and the drift effects should cancel
out. (Joachim pointed this out some months ago, especially the
consequent use of this principle in ARP synthesizers. Even for the 
scale trimmers!)

JH.