Has anybody made this ESP (project 66) mic preamp - Having problems with the pot

[Skruffyhound]

Hey. I'm not really getting any adjustment out of the pot despite trying different tapers/values and changing the minimum resistance across the pot (nominal 100K in schem.)
Gain is fine seemingly, but only when pot resistance is virtually zero do I get signal passing.

Any ideas?

http://sound.westhost.com/project66.htm
       

[PRR]

Gain pot needs to be 10K REVerse-audio.

Otherwise all the gain is bunched-up at one extreme.

In bench, wire a normal Audio so it turns the wrong way.

[FunkyGibbon]

Yep. As Paul said, normal audio pot wired in reverse. It then then gives a wide range of control over the sweep of the pot. When you do this, it won't be a 'volume' control per se, as the volume will drop as you turn it up. You can call it 'attenuate'. You can mod the circuit if you need more gain. The instructions are on the project page. I've been using mine for years and it sounds great. It's power use is also very meager. I considered using a power supply with it, but it runs for months on just a pair of 8.4V NiMH rechargeables, for + and - 8.4V. I'm not sure what effect this might have on headroom, compared with +/- 15V.

A highly recommended project.

[Skruffyhound]

Thanks guys, I'll check through it again tonight, maybe I can find a mistake.
I did read the project notes, so I have tried log / rev log pots.
Good to know someone has it working though.