Hum on one of my A12 pres

[neirbod]

Hello,

I recently purchased some SCAs used off the Gearslutz forum. In the process of fully assessing the pres, I found that one A12 has a hum that sounds similar to a ground loop. I recorded 10 seconds of the hum, followed by 10 seconds of a non-humming A12.

There is hiss on both samples as I cranked the gain to better hear the hum.

Other possibly relevant info - the humming A12 is next to the PSU, and there is a slight crackle when I wiggle the gain knob, like a bad connection. The hum is present at all gain levels, but is louder with more gain.

I did not build these and honestly have no desire to learn how. If these symptoms suggest an obvious fix I could try it, but otherwise I am looking for how to get a more seasoned pro to help me repair it.

Thanks[/url]

[neirbod]

Here is the audio file:


[url]http://nomadrecordingstudio.com/SCA/[/url]

[tpryan]

Check everything in this thread and let us know what you find: http://seventhcirclestudios.com/SCA/php ... php?t=1728