"mapping voltage" on an analog potentiometer using a voltage divider
It appears that you are using the potentiometer incorrectly for two reasons:


You are using it as a variable resistor instead of a potentiometer.
You have it on the speaker line. You should have it before the amplifier.








simulate this circuit &ndash; Schematic created using CircuitLab

Figure 1. (a) Rheostat. (b) Potentiometer. (c) Volume control.

Your diagram doesn't show the resistance value of the potentiometer or the speaker but let's say they are 1k and 8 Ω. 1k is a huge resistance to put in front of an 8 Ω speaker and only a small fraction of the power will get to the speaker. It's only when you decrease it to &lt; 100 Ω that you can probably hear any change.

For a volume control we use a potentiometer. Note in Figure 1b that this has the bottom terminal connected to circuit ground. That means that as we slide the wiper up from the bottom the output voltage will vary from 0% to 100% of whatever is coming in on the IN terminal. (The output will actually be somewhat less if you have a load connected to the wiper. It will be very much less if you tried to connect your 8 Ω speaker to the wiper.)

What you need to do is get a proper amplifier circuit and hook it up as shown in (c). This way the volume control only has to deal with low powered signals and the amplifier boosts these to drive the speaker directly. That's how all amplification systems do it.

You need to draw proper schematics (component symbols, part numbers, designations - R1, R2, etc.) to help you and others understand your circuit. There are many online free tools and there is a CircuitLab button on the editor toolbar on this site (that I used for Figure 1). Have fun.