[]|[ GorE]

Not that it practically matters but still,
if i turn my pot more than 50% and go-on towards a full turn i can hear noise,noise that keeps constant irrespective if whether i have music playing and the inputs are connected or not.

Now heres the thing.The noise is attenuated by quite some amount if i touch the "virtual ground" ie the ground of either input or output jacks or on the protoboard itself.

Notes :

cmoy is still in the open.Will fit into a box tomorrow.

9400uf Wallwart filter caps.
Fully fledged lm317t circuit with maximum ripple reduction as given in the datasheet.Ouputting 12.71 V reduced from wallwarts output(varying from 15.5V to 18V).
I get perfect +6.4V and -6.4V (measured directly from the opamp pins).

I have 0.1uf polypropylenes connected to V+ and V- of the opamp pins.
No components even become warm.

No noise if pots set to below 50% or so.
Pot has been soldered perfectly well.Confirmed by my uncle whose an instrumentation engineer.He could find any problems in the circuit,btw.
Gain = 3.


Any suggestions ?
Thanks.

 

[Sinbios]

This happened with my pimeta too, and only when I use the wallwart.

 

[morsel]

Is this white noise or hum? Once you have your circuit properly cased and grounded, hum that subsides when touching the inputs or pot should go away. Input ground, case, and pot shaft/housing should be tied together.

 

[leftshoe]

Sounds alot like a grounding problem.Check to make sure all parts that should be grounded are.

 

[]|[ GorE]

leftshoe,you had to scare me didnt you ? my ohmmeter beep function works from every virtual ground point to every other.

And its white noise.no hum at all.

 

[Francis_Vaughan]

Instability can sometimes manifest itself like this. A little odd, but plausible. So you may find some value chasing a solution in that direction.

 

[]|[ GorE]

thanks for the replies,everyone.I am gonna ignore this problem since it only occurs at ear bleeding volumes......