1
\$\begingroup\$

I was hoping I could get help with a design I have breadboarded/diagrammed with regards to a low level signal still present when I have my volume pot turned all the way down. When I turn my volume control down all the way there is a low volume/high treble sputtering distortion signal that's still audible. I thought is was a grounding issue on my volume pot but it's not coming from there, not exactly sure where it's coming from. I hope I tagged this correctly as I'm still learning proper terms.

enter image description here

enter image description here

\$\endgroup\$
  • \$\begingroup\$ It looks like you have 2 wires from your power supply going into the same row on your breadboard. \$\endgroup\$ – brhans Jun 20 '19 at 0:52
  • \$\begingroup\$ @brhans where is that happening? \$\endgroup\$ – greyBow Jun 20 '19 at 12:22
  • \$\begingroup\$ Left side of your pic. Black & Brown wires both plugged into the blue - row. \$\endgroup\$ – brhans Jun 20 '19 at 12:31
  • \$\begingroup\$ Ah, those two wires just ground my 1/4" TRS inputs \$\endgroup\$ – greyBow Jun 20 '19 at 13:26
1
\$\begingroup\$

You need to reduce R11 to zero if you expect the volume to go to zero.

If you are hearing distortion, the output may be clipped. Since they put the volume control after the amp, this is a possibility. Do you have a scope?

I don't care for this design. LM386 are designed to drive speakers, so although they will work, they are not the best choice. The output impedance is variable, it depends on the volume setting.

| improve this answer | |
\$\endgroup\$
  • \$\begingroup\$ When I take R11 away and go straight to ground I have the same issue. I do have a scope, but I'm just learning by doing at this point, just getting started, so I'm not sure how to fully use the tools. At what points should I check with the scope? \$\endgroup\$ – greyBow Jun 19 '19 at 21:49
  • \$\begingroup\$ I don't see a ground connection to the bottom row on the breadboard. \$\endgroup\$ – Mattman944 Jun 19 '19 at 22:02
  • \$\begingroup\$ it's off the edge of the photo at the very bottom of the board, there is one though. \$\endgroup\$ – greyBow Jun 19 '19 at 22:11
  • 1
    \$\begingroup\$ What is your input? Is the distortion present even if the input is shorted? If yes, then look at the output of each stage and see where the unwanted signal exists. \$\endgroup\$ – Mattman944 Jun 19 '19 at 22:59
0
\$\begingroup\$

The contacts on many breadboards make poor connections. Many cheap volume controls make a poor ground connection with the slider.

| improve this answer | |
\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.