Sound Skulptor forums

Build help and troubleshooting => MP566 Tube microphone preamplifier => Topic started by: wreutz on May 29, 2021, 01:03:22 PM

Title: Bugfinding - low level then normal operation
Post by: wreutz on May 29, 2021, 01:03:22 PM

Hi all,

I have a strange problem with my MP 5.66 (built some years ago, been on the road and studio):

Sometimes (mostly when I connect it to my X32 as an insert) I either get a very quiet but extremely distorted signal or only a quiet signal and when I crank the gain of my X32 which essentially delivers a high level input to the MP 5.66 and then lower the gain back to a normal level it works without problems the rest of the show(s). It like cleaning the pipes with a high input level ...

Any ideas what the problem could be?

I ruled out my 500 Rack (Neve R6), I changed the tube, I changed cables, channels and used it both as an insert an connecting a mic directly - nothing solved the problem it still occurs infrequently ...

Any directions on how to solve this is highly appreciated 😉 

Title: Re: Bugfinding - low level then normal operation
Post by: JPK on May 31, 2021, 09:02:55 AM

This sounds like a dry solder joint making intermittent connection.
Try tapping on the various components of the PCB with a pen to try to reproduce the issue.
It might could help you locate it.
Then reflow any suspicious solder joint.