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Volume pot turned all the way down but sound still a little loud
Posted: Thu Jul 20, 2017 9:51 pm
by tinkerBOY
While waiting for the USB sound card i thought i could setup another pi to test/improve the mono PWM audio i used on my first build. This time im using no low/high pass filter. Just the audio amp(PAM8302A) directly connected to the pi zero's GPIO 18. To my surprise it sounded great and can't seem to hear any difference from my
first build with filter.
I made another change by placing the volume pot between the pi's gpio18 and the audio amp which i think is a good practice. The only problem is, the sound is still a little loud even if the volume pot is turned all the way down. Maybe im doing it the wrong way. Im not sure.
- IMG_1448.JPG (2.37 MiB) Viewed 9363 times
Any help or input is welcome and will be very much appreciated! Thank you!
Update:
It looks like the
PAM8302A doesn't need any filter after all.
Re: Volume pot turned all the way down but sound still a little loud
Posted: Thu Jul 27, 2017 11:19 pm
by Lphillimore
Where is the ground for your vol pot? Add that and re-test.
Minimum you'll need is GND, L or R channel IN and corresponding channel out.
Re: Volume pot turned all the way down but sound still a little loud
Posted: Thu Jul 27, 2017 11:34 pm
by tinkerBOY
Lphillimore wrote: ↑Thu Jul 27, 2017 11:19 pm
Where is the ground for your vol pot? Add that and re-test.
Minimum you'll need is GND, L or R channel IN and corresponding channel out.
Im not sure what you mean by GND for VOL. I'm using a 3-legged pot. Can you elaborate please?
On the back of the board, GND and A- are jumper wired connected.
Re: Volume pot turned all the way down but sound still a little loud
Posted: Thu Jul 27, 2017 11:55 pm
by Lphillimore
zeroboy wrote: ↑Thu Jul 27, 2017 11:34 pm
Lphillimore wrote: ↑Thu Jul 27, 2017 11:19 pm
Where is the ground for your vol pot? Add that and re-test.
Minimum you'll need is GND, L or R channel IN and corresponding channel out.
Im not sure what you mean by GND for VOL. I'm using a 3-legged pot. Can you elaborate please?
On the back of the board, GND and A- are jumper wired connected.
3 Pin volume pots still have a GND, In and Out.
For any builds I've done ive used 5 pin pots, which have dual in and out channels. Still need to wire up GND though
If its a B103 the pinout should follow the 5 Pin.
You have wired your IN and OUT on vol pot but nothing attached to ground.
If you add this, you should find it works...
Re: Volume pot turned all the way down but sound still a little loud
Posted: Fri Jul 28, 2017 12:50 am
by tinkerBOY
Lphillimore wrote: ↑Thu Jul 27, 2017 11:55 pm
zeroboy wrote: ↑Thu Jul 27, 2017 11:34 pm
Lphillimore wrote: ↑Thu Jul 27, 2017 11:19 pm
Where is the ground for your vol pot? Add that and re-test.
Minimum you'll need is GND, L or R channel IN and corresponding channel out.
Im not sure what you mean by GND for VOL. I'm using a 3-legged pot. Can you elaborate please?
On the back of the board, GND and A- are jumper wired connected.
3 Pin volume pots still have a GND, In and Out.
For any builds I've done ive used 5 pin pots, which have dual in and out channels. Still need to wire up GND though
If its a B103 the pinout should follow the 5 Pin.
You have wired your IN and OUT on vol pot but nothing attached to ground.
If you add this, you should find it works...
Thank you!
i got it working.
Re: Volume pot turned all the way down but sound still a little loud
Posted: Mon Jul 31, 2017 9:46 pm
by firestw152
Update:
It looks like the
PAM8302A doesn't need any filter after all.
[/quote]
So the filter is not needed at all? Man I would have loved to know that sooner before I spent all that money on the resistors and capacitors.
Re: Volume pot turned all the way down but sound still a little loud
Posted: Mon Jul 31, 2017 9:57 pm
by tinkerBOY
firestw152 wrote: ↑Mon Jul 31, 2017 9:46 pm
Update:
It looks like the
PAM8302A doesn't need any filter after all.
So the filter is not needed at all? Man I would have loved to know that sooner before I spent all that money on the resistors and capacitors.
yeah me too.
I actually have assembled some filters.. but looks like i don't need them anymore.
Re: Volume pot turned all the way down but sound still a little loud
Posted: Mon Jul 31, 2017 10:04 pm
by firestw152
zeroboy wrote: ↑Mon Jul 31, 2017 9:57 pm
So the filter is not needed at all? Man I would have loved to know that sooner before I spent all that money on the resistors and capacitors.
yeah me too.
I actually have assembled some filters.. but looks like i don't need them anymore.
[/quote]
hey one more question do you have the radioshack 5 pin jack for the headphones? If you do, do you have a picture of the wiring. Or know of a schematic somewhere because I am having serious problems trying to get audio to work on retropie. I have tried both USB and gpio audio and none of them work correctly.
Re: Volume pot turned all the way down but sound still a little loud
Posted: Mon Jul 31, 2017 10:15 pm
by Lphillimore
Guys, checkout PWM2 - it's in the early stages but seems to be a massive improvement and negates the need for heavy filtering etc.
Re: Volume pot turned all the way down but sound still a little loud
Posted: Mon Jul 31, 2017 10:29 pm
by firestw152
Lphillimore wrote: ↑Mon Jul 31, 2017 10:15 pm
Guys, checkout PWM2 - it's in the early stages but seems to be a massive improvement and negates the need for heavy filtering etc.
Wait im sorry im not informed enough to know what that is, is it like another type of amp? Can I get a link to read what it is.
