[PYROTAK]

i think its a grounding problem although i dunno how to fix it.

my mint buzzes like mad when i turn up the pot. and its even worse when a source isn't plugged in.

anyone know how to fix it?

 

[tangent]

- What power source are you using?

- Metal case?

- What kind of DC input jack, if any?

- What kind of I/O jacks, and are they isolated?

- Metal pot shaft?

- What happens when you touch metal parts?

- Does the problem change when you change the source?

 

[PYROTAK]

ok.

well im using the radioshack 15 volt DC plug.

using a radioshack DC female plug

using a panasonic evj pot.

using a hammond metal case with plastic bezels.

when i touch a metal part of the case it gets worse.

nothing changes when i touch the pot, since the pot has a plastic shaft.

and the intensity of the buzzing changes per source. when i plug it into my computer it isn't as bad as when i plug it into my iriver.

and on the bottom of my hammond between teh PCB and the metal i got a piece of teflon.

thanks for the help.

 

[tangent]

Try connecting anything metal that changes the sound to virtual ground, unless it's already connected to something else in the circuit (like V-). This includes the case itself, and ground connection of all the I/O jacks. You can do this temporarily with alligator jumpers to see if it helps before adding wires. On the case, be sure to scrape through the anodization to get good contact.

That power supply is either switching-regulated or unregulated, so it could be the source of the noise. Try powering the amp from batteries temporarily to see if that helps.

 

[PYROTAK]

what exactly is the virtual ground?

is it the v-?

im not exactly sure what you are talking about...but thats only becuase i am electronics dumb.

 

[MisterX]

See the holes marked with the G?
(not the IG)


Click the pict for the super sized version.

 

[PYROTAK]

thanks dude you rock. its much too bad that im currently in japan and really cannot do anything about it until august 6 lol.

 

[PYROTAK]

so im back from japan and did what the dude told me to do, but there is still buzzing.

do you think my pot is just busted or its becuase im using solid conductor wire?

 

[tangent]

The wire isn't a problem, in and of itself. If due to its lower flexibility you've broken a wire, that's different.

The pot could be a problem, but the fact that the symptom changes when you plug a source in suggests a grounding problem.

 

[PYROTAK]

hmm.

ok so im going to take a picture of the board tomorrow and so that you can see if maybe i wired something wrong.

 

[PYROTAK]

anyone know a free host i can use?

 

[PYROTAK]

in case anyone cares,

it turns out it was the crappy ass RADIOSHACK wall wart making all the signal noise.

i got another wallwart connected and it has no more noise.

wow radio shack sucks.

 

[tangent]

Quote:

wow radio shack sucks.

I wouldn't say that. It's a perfectly useful wall wart for some things. Just not audio.

You could instead have added a linear regulator after it, as described in a recent thread.

 

[PYROTAK]

i didn 't mean the shop stinks.

i meant the wall wart that they have stinks.

so im going to search about this linear regulator thing and see if im competant enough to make one.

 

[tangent]

Quote:

i meant the wall wart that they have stinks.

I know, and I'm telling you that that wall wart is perfectly reasonable for what it is. Your expectation that it would be good for audio is what is out of line. There's a reason that the 330mA Elpac WM-080 costs $30 at wholesale electonics distributors while the ~1A Radio Shack 13.5-30V costs $22 and you get a store and pretty packaging.