Author Options:

"Add on" radio volume control Answered

I have a simple radio alarm clock with digital volume control.  But, the lowest available volume is still too loud.   How can I make it softer.  Can I simply solder in a resistor in the speaker wire, or add a pot?  Or is it more complex than that...  (if so, what resistance?)


Thanks for this to both.

I ended up checking things out at my local electronics supply store and they didn't have every possible resistor value (of course) . I ended up buying a 2 watt 10 ohm resistor (and a 1 watt 2 ohm) and putting the first into the circuit. It worked exactly right and so I made it permanent. It was a bit hard to stuff the case back together as everything fits quite tightly (I added some extra wire just in case) but with a small amount of persuasion and pushing it went back together and all is workign very well! Thanks again!


10 months ago

Yes a resistor...

Assuming a low cost radio will have a 4 ohm speaker...

As a first try I would use a 1 ohm, 2 watt resistor should reduce volume by 1/5 or you could wire two in series to reduce volume by 1/3..

I agree that placing a resistor in series with the speaker is the best, easiest, way to make it more quiet; i.e. make it so the speaker emits less power.

Although, I think the size of the resistor required will be closer to 10 ohms or 20 ohms, than to 1 or 2 ohms.

This guess is based on two foundation guesses: First, I am guessing the impedance of the existing speaker is higher, like 8 ohm or 16 ohm. Second, I am guessing a large amount of attenuation (like maybe reducing emitted power by a factor of 10) will be required to give a perceived, to the ear, decrease in volume.

Actually, as you say with the ellipsis (...), it will likely be an exercise in trial and error to find the resistor that attenuates the sound to the Goldilocks, "just right", amount.

Thank you Jack,

You are probably correct about the speaker ohms, being 8 or 16, as I have not owned a radio for a decade.

I listen to my car radio and an iPhone app can reach any radio in the world including Science Friday.

Then the resistance would need to take values of your good guessing and since our hearing is logarithmic a 10 attenuation is also logical..

Thanks for this. In fact on the wall of the local electronics store is a hundred products... I picked up a 1 w 1 ohm pair and a 2 watt 10 ohm pair. I will try the latter first.

Now another question but I will start another thread.