Potentiometer taper too loud for low volume

Thread Starter

ghulse

Joined Oct 19, 2023
8
I've made a miniature stereo using a bluetooth/MP3/SD card player and an Adafruit Class D 20 watt stereo amp, powered by a 12 volt DC plug that is split between these two devices. It's controlled by a volume knob (10K Ohm Single Linear Taper Dimmer Potentiometer with on/Off Switch) to turn the device on-off and control volume. The device turns on at about 9 oclock but jumps to a fairly high volume before I even get to 12 oclock position. No low volume to speak of. I chose a 10K Ohm pot for no particular reason. Might a 1k Ohm pot give me better low volume?
 

Alec_t

Joined Sep 17, 2013
14,225
Welcome to AAC!
10K Ohm Single Linear Taper Dimmer Potentiometer with on/Off Switch
For audio use you want a log taper, not linear. The logarithmic type 'stretches out' the volume change at the low volume end.
A 1k pot wouldn't improve things.
 

Audioguru again

Joined Oct 21, 2019
6,614
A volume control is supposed to have a Logarithmic taper and is marked "A" so that it matches the logarithmic sensitivity of our hearing.
When you turn down a linear pot to halfway, the loudness is turned down only a little, turn it down more and it is still too loud.
 

crutschow

Joined Mar 14, 2008
34,055
You can add a resistor from the output to ground, to give the pot a quasi-log output.

The LTspice sim below shows the output on a linear scale (yellow trace) and a log (dB) scale (green trace).
The log output would be essentially a straight line for a true log.

You can adjust the value of R2 to give the results you want.

1698854185155.png
 

Thread Starter

ghulse

Joined Oct 19, 2023
8
Welcome to AAC!

For audio use you want a log taper, not linear. The logarithmic type 'stretches out' the volume change at the low volume end.
A 1k pot wouldn't improve things.
Thanks for this info. I'm impressed with all of the responses to my question. Was expecting to be criticized for not providing a schematic. But so I ordered a log taper from Adafruit. Thanks again. Very helpful!
 
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