I am on a project of making a music system which will be able to output 6 speakers. I want to control the gain of each six TDA2030/50 ICs with a single potentiometer.

Here is a schematic example of 2 ICs controlling with a single potentiometer, I have tried but does not seem to work correctly.


simulate this circuit – Schematic created using CircuitLab

When I tried this schematic, I get music sound but also with music, it offers some free noises.

Now some of you may think that this might be the answer I am looking for but, unfortunately, the answer schematic given here is not understandable to me as a beginner, and I don't want to use another TDA IC to generate a static voltage or something like that which may create difficulties for me to understand. I only want to use either BJTs (2N2222A) or MOSFETs (IRFZ44N), so if anyone here has a solution for me, please do me a favor by sharing it with a proper understandable schematic and pointing my mistakes respectively for a beginner like me.

Please avoid suggesting any kinds of ICs for performing this action till there are other ways left.

  • \$\begingroup\$ usage of fet makes more sense to me in this circuit. But defenetly not IRFZ44N, more something like BF245 \$\endgroup\$
    – fifi_22
    Commented Jan 8, 2021 at 7:46
  • \$\begingroup\$ Will i not able to use BJTs instead? with something more circuitary? otherwise 2N4392 n channel JFET , the one you mentioned here isnt available in my locality \$\endgroup\$ Commented Jan 8, 2021 at 8:00
  • 1
    \$\begingroup\$ Is your schematic definitely correct? Q2 has its emitter connected to +12v. \$\endgroup\$
    – HandyHowie
    Commented Jan 8, 2021 at 8:41
  • \$\begingroup\$ @HandyHowie oops sorry that emitter should have been connected to the inverted input of 2nd TDA, I ve now fixed it, I didnt make this miskate in real life but here while drawing \$\endgroup\$ Commented Jan 8, 2021 at 8:55

2 Answers 2


If we look at the functional schematic in the datasheet:

enter image description here

then it is easy to recognize the common non-inverting (opamp based) amplifier structure. I marked the feedback which sets the gain.

The TDA2030 does not have an input for adjusting the gain.

I do not "see" how your proposed circuit can even work as the transistors cannot "work like a resistor" in the way that would be needed for this. And even if it worked, the transistor will be somewhat non-linear and that will introduce distortion in the feedback circuit which really should be linear.

The solutions that I see are to use a different audio amplifier, one that does have a volume (or gain) control input.

If you want to keep using the TDA2030 or any other amplifier without a volume control input then for two channels, use a "stereo potmeter". For more channels, use a volume control IC, this is what is used in many commercial multi-channel amplifiers.

  • \$\begingroup\$ Does those 150k and 4.7k along with 2uf capacitor auto adjust the gain? Does it not depend on Input vcc or non inverted input voltage ? \$\endgroup\$ Commented Jan 8, 2021 at 9:23
  • \$\begingroup\$ @SubhaJeetSikdar How do you mean "auto adjust the gain". This is a very common way to make a fixed gain using feedback. The 2 uF capacitor is there to make the gain at DC (0 Hz) equal to 1. No, the gain does not depend on Vcc, the feedback takes care of this. I suggest that you study amplifier / opamp circuits with feedback as you appear to lack basic understanding of these type of circuits. \$\endgroup\$ Commented Jan 8, 2021 at 10:05
  • \$\begingroup\$ you are quite right... I am quite newbie in Audio and opamp related field here, the only thing I haven't yet been able to figure out that how you calculated the values of the 2 resistor 150k and 4k that's why I found the potentiometer way myself. if u know , please either let me know or give m a nice article link to read \$\endgroup\$ Commented Jan 8, 2021 at 11:15

Don't dink around with the outputs. Use a volume control at the input. One potentiometer connected to the inputs of two amplifiers.

Like this:


simulate this circuit – Schematic created using CircuitLab

Where C1 and C3 are the same as in your diagram. The gain of the 2030 is fixed - you can't change it. Just vary the amplitude of the input signal.

Most amplifiers work that way. The amplifier has a fixed gain, and the volume control varies the amplitude of the signal going into the amplifier.

  • \$\begingroup\$ This is the sensible way to do it. The only improvement, although it adds another IC, would be to buffer the output from the pot to drive multiple power amp inputs. \$\endgroup\$
    – user131342
    Commented Jan 8, 2021 at 9:57
  • \$\begingroup\$ @henros u mean something like preamp right? \$\endgroup\$ Commented Jan 8, 2021 at 11:20
  • \$\begingroup\$ @SubhaJeetSikdar: No. That means an opamp as a buffer. Gain of 1 or gain of -1. \$\endgroup\$
    – JRE
    Commented Jan 8, 2021 at 11:41
  • \$\begingroup\$ @JRE Oh got it now. \$\endgroup\$ Commented Jan 8, 2021 at 12:39

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