K4001 gain switch

I want to build this circuit, but i want to add a switch to turn the gain on and off so it would be an overdrive switch. Which part of the circuit controls the gain e.g. R1 or C1 etc? I am used to working with the LM386 chip where the gain is controlled by a cap or resistor between pins 1 and 8 but i’ve never worked with the TDA2003 chip before. Can anyone help me as to which part of the circuit sets the gain?


We’d suggest you download the datasheet for info regarding the gain setting, as you have to make sure that you operate the unit within the specs.

I don’t think you understand as it doesn’t say anywhere on how to adjust the gain. I think it may be C4 which sets the gain. If so, would i need a variable capacitor to adjust the gain, and of what value? Also, would leaving out this capacitor make the input sound clean?

Many Thanks,

As you in the datasheet, this amplifier simply doesn’t have an external adjustable gain. The circuit part with the capacitor is for the feedback.
Gain can NOT be adjusted.

Ok, but what if i wanted to put a switch in, to turn the gain on or off, is that possible?


EDIT: I’ve just been doing some research on the TDA2003 chip and looking at their test circuits in the datasheet (one of them, by the way, is pretty much identical to this project in terms of layout) and i have found that R1 sets the gain. So couldn’t i just install a potentiometer of the same value as R1 instead of R1?

You probably could, but you would have to make sure the gain stays within specs, to avoid oscillation or instability of the amp.