ASM-1 Pots: log or lin?

[Gene & Debby Stopp]

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> From: Heiko Bajus <uhb17 at rzserv2.fh-lueneburg.de>
> To: synth-diy at horus.sara.nl
> Subject: ASM-1 Pots: log or lin?
> Date: Thursday, July 31, 1997 3:38 AM
> 
> Hi,
> Please give me an Advice. Which Pots on the ASM1 frontpanel should be log
> and which should be lin?
> 
> Thanks, Heiko
> 

Some panel pot parameters are either inherently linear or internally
exponentiated so as to be perceptually linear, and so are best controlled
by linear pots:

VCO Frequency Coarse Tune
VCO Frequency Fine Tune
VCO Initial Pulse Width
VCF Cutoff Frequency
EG Sustain
VCA Initial Gain
LFO Frequency

Some parameters use the pot resistance directly as part of an R/C network,
and therefore are very sensitive when the resistance is near zero ohms. To
allow finer resolution per rotary pot movement for these settings, a log
(audio) pot is sometimes preferred:

EG Attack, Decay, Release
Glide (Portamento) Time

Some parameters are linear but the use of a log pot allows fine control at
small signal levels, so that there is more control of subtle changes:

VCO Modulation Depth
VCF Modulation Depth
Audio Signal Level (any module)

Some parameters may actually benefit from a reverse log taper, when higher
signal strengths become critical in situations where feedeback is used:

VCF Resonance

These are just suggestions - the builder is free to either come up with his
own rationalizations, or perhaps just use up the parts that happen to be
laying around. My ASM-1 banana jack system uses all linear pots (I felt
cheap at the time), and it works just fine for me. I like to deal with the
machine's internal relationships directly - I guess that I like to "feel"
the R/C ratios with my fingers.

- Gene