could someone who understands potentiometers please explain something to me

[lordofgrug]

Hi, please be kind, it's my first post.
So i need to replace a potentiometer that's been crackling in a joe meek, twin q preamp. I've pulled it out, the manufacturer is alpha, printed on it is '10c5k' and stamped on the back is '7g2' What confuses me most is the 'c'. I have deduced it refers to the resistance taper. looking at the manufacturers taper specs it appears that taper type 'c' is a reverse audio taper. On the preamp it acts like a regular audio taper, hard left is 0 hard right is 100. why is this? I was hoping to replace it with a linear type 'b', as i prefer the feel of linear for my gain knobs, but will this make it backwards?
Thanks for reading through all that, your time and advice is really appreciated

[Pano]

I'm not sure why they would have used reverse taper, I mostly see those in balance controls. But someone may step in with the answer.

A linear pot will not give you a linear feel, quite to opposite. That's what the log curve pots are all about. But a linear will work, for sure.

[simon7000]

It is most likely in a feedback circuit, so the action is reversed. You probably do not need to replace the pot, use a chemical like De-Oxit on it. If it actually has a burned spot then you should look for DC on the pot wiper, most likely from a leaking electrolytic capacitor.

[lordofgrug]

Thanks simon, i figured it was something like that.

Now i'm more confused as to why a linear pot wouldn't give me a linear feel. i want it to act like, hard left 0% middle 50% and hard right 100%. at the moment its like hard left 0% middle about 30% hard right 100%

[DJNUBZ]

Originally Posted by lordofgrug

Thanks simon, i figured it was something like that.

Now i'm more confused as to why a linear pot wouldn't give me a linear feel. i want it to act like, hard left 0% middle 50% and hard right 100%. at the moment its like hard left 0% middle about 30% hard right 100%

The reason is that Audio isn't linear, it's logarithmic. To gain 3 db you must double your power. Personally i have replaced some faders on a mixer with log pot and found that I didn't like the way they performed so I switched to the linear pot. On something like a preamp, where you aren't adjusting that much I don't think it will change how you use it much either way.

[lordofgrug]

ok, i think i understand. so is there any way i can make it "feel" linear. like 3=30% 8=80% ? at the moment i have very little precise control after about 70%. even very small adjustments on the knob, make huge adjustments to the sound.

[digits]

you can try to wire up a fake law pot, or just buy a logarithmic pot.