TPA3122D2 Pot Problem

Ripcord

Member
2013-09-25 2:21 am
USA
A couple of years ago I built a little TPA3122D2 amp that I found on the forum and decided to put it in a cigar box. It's a BTL config with a 15vdc wall wart PSU. All by it self it sounds as expected, pretty darn good. I added a big DC meter for the steampunk look, and a volume pot and on-off switch. Problem, the volume pot is definitely causing trouble. I tried a 50K dual pot, (see atachment). Didn't work. Sound is distorted and broken up. I guess the pot value is to high? Maybe a 1K or 5K? Not sure what the output impedance is of my laptop but will mainly be using with cell phone output. Any hints?
 

Attachments

  • Pot.jpg
    Pot.jpg
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  • SP Amp Front.jpg
    SP Amp Front.jpg
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  • SP Amp Back.jpg
    SP Amp Back.jpg
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Ripcord

Member
2013-09-25 2:21 am
USA
Well I think I solved the problem. I changed out the dual 50K pot with a dual 5K pot but what I think made the difference was grounding the shields on the pot to the AC ground plug on the IEC outlet. After the 5K pot change, it was still distorted and glitchy but after the ground strap it came up fine.
 

rayma

Member
2011-04-29 8:37 pm
Well I think I solved the problem. I changed out the dual 50K pot with a dual 5K pot but what I think made the difference was grounding the shields on the pot to the AC ground plug on the IEC outlet. After the 5K pot change, it was still distorted and glitchy but after the ground strap it came up fine.

The amplifier needs both a hot and return (sometimes called common or ground) input connection.
An electrical signal flows in a loop, so just one connection from the pot to the amp is not enough.