Any electronics experts?

I have a portable PA thing, where the volume goes from nought to deafening within about 10% of the pot diailing.

Thinking the pot might be faulty, I replaced with another 50k for 50k.
This didn’t cure the problem.

What would happen if I fitted a 100k pot instead ?.
Would this extend the range from zero.
So instead of it being loud at say 10% dial, it would be the same loudness at 20% dial.
With full dial being full volume.
and what about a 200k pot.

Could these pot sizes have any implications on the elctronics later down the line.

The resistance value will be matched to the rest of the circuitry.
It is likely that the original (failed) potentiometer had a logarithmic scale Did you replace it with an identical one, or just one with the same resistance?

B50K with another B50k, which from what I can see is a linear.
But the new pot is the same, goes from silent to deafening within about 10%.
Measuring the old pot, I’d say about 5 ohms

I found this comparisoin between lenear and logarithmic pots.
https://www.google.com/search?q=logarithmic+vs+linear+pot&client=firefox-b-d&tbm=isch&source=iu&ictx=1&fir=GmcqlJbIcIbXvM%2CwVNulXAsG0XFrM%2C_&vet=1&usg=AI4_-kRsBloWMzA5F6xc4GsIFMg1hYf8kA&sa=X&ved=2ahUKEwj3hMvqptHwAhUtAWMBHbLABD8Q_h16BAgQEAE#imgrc=GmcqlJbIcIbXvM

It does appear that the one I took out is linear, the increments measure constant across the range. As it’s blasting my lugs out at 10% dial, then a logarithmic pot should give the same volume at about 45 dial, (provided the graph is accurate) which would in theory make it more workable in social environments.
For the sake of a few quid, i’ll try a log pot.

1 Like

Volume pots are usually Logarithmic, (unless its a peculiar circuit). The usual law is 10% of maximum at 50% rotation clockwise.

Pots are often marked with a letter to show which law.
A = Linear (50% at 50%)
B = Log (10% at 50%)
C = Anti-log (90% at 50%)
(Not all manufacturers follow these markings, but A is always linear.)

A Balance control sometimes has a pair of pots (B and C) wired such that at the mid point the outputs from both are 90% but as it is turned in either direction one of them drops towards 0% and the other rises to 100%. This loses the least sound at balance.

Chances are the correct Far East parts bin was empty and they just stuffed in a linear one of the approx correct value!

It happened on some speakers I bought - wrong Fs bass units, wrong tweeter cross-over cap, etc…

(Edit for more info about pots)

It’s been like it since new, I just never really bothered until a few weeks ago where I was getting hassled from the wife about it being too loud.
To be fair, she was right, trying to tweak it to an acceptable volume is difficult.
It’s far too loud at 10% dial.

Probably cool if youre 18, but not when you’re in your late 50’s.

Just a follow up.

I tried again with a 50ohm logarithmic pot, the difference is phenomenal.
I’ve much more gentle volume control, from 0 to about 40% dial.

Much more controllable where you want it to be.

2 Likes