question about electronic parts?

Question

I don't have a tone control on a radio I have, and it's a little annoying, I want to put a capacitor across the speaker terminals to cut off just a little bit of the high end.

What value do I need to use?

Answer 1

Yes you can do this (with a change), though it's not ideal. "Realist 2006" is close, but not quite correct.

1) Never connect a large capacitor directly across the terminals of an audio power amp. It might oscillate out of control.

2) "Realist" is correct that you need a resistor in series with the speaker and amp circuit. But assuming the speaker is 8 ohms (give or take a factor of 2) you will lose most of your volume with a 1K resistor & all of the high frequencies.

3) Place an 8 ohm resistor in series & make sure it is a 1 or 2 watt resistor. More wattage if it is a powerful radio. You will lose some volume (3 dB) but not too much.

4) Place a capacitor across the speaker terminals. Assume that you want to attenuate 10 kHz signals by 3 dB. Then the impedance of the cap at 10 kHz should be 8 ohms in magnitude. Z = 1/(omega*C) So the cap. value should be approx. 2.0 uF. DO NOT use a standard electrolytic cap.! A large plastic film cap. will work well.

The calc. in part 4) isn't quite correct, but close. Increase capacitance or decrease to suite your taste. Increasing will mute the treble more.

Answer 2

I guess you could try the 1 uf as suggested above, but the speaker is the wrong place to be doing this. The impedance of the speaker is so low that the bypass of any reasonably sized capacitor won't make much difference. You really need to find a place in the circuit that has a higher impedance.

Answer 3

Start with 1 microfarad.

Answer 4

Contact or look up a company called PAC. they have a xover guide that will tell you more than you ever wanted to know.

Answer 5

last answer plus 1k ohm in series