Tube Tech CL1b issue

[Dimitridask]

I recently ran into an issue with my Cl1b where audio fades in and out randomly. If I have a mic patched in and monitor the noise floor coming into the daw, after some time the signal will completley cut out. If I clap my hands or speak/ make noise into the mic the signal will return to the average noise floor. It’s as if there’s a gate randomly. Unit was working fine until this point, fresh tubes. Tested different cables as well. Side chain is also off. If I’m continuously running audio into the unit the level will drop about 5-10db and then return to normal. I’ve heard it could be a burnt fuse, just want to make sure it could be that before I take it apart.

 

[TwentyTrees]

When I've had situations where audio has been lost but a loud signal has then "punched through" and restored normal operation, it's tended to be oxidation on connectors or switches. If you can narrow it down to that, then exercising / cleaning / replacing the culprit has done the trick. I've also had that with bad electrolytic coupling caps in the signal path.

Are there particular conditions where the issue comes on? Particular settings / functions? I'm guessing not, from your phrase "fades in and out randomly", but if you can discern a pattern that will help you divide and conquer.

 

[mjrippe]

Definitely not a fuse. A cold solder joint can cause this sort of behavior.

 

[Dimitridask]

When I've had situations where audio has been lost but a loud signal has then "punched through" and restored normal operation, it's tended to be oxidation on connectors or switches. If you can narrow it down to that, then exercising / cleaning / replacing the culprit has done the trick. I've also had that with bad electrolytic coupling caps in the signal path.

Are there particular conditions where the issue comes on? Particular settings / functions? I'm guessing not, from your phrase "fades in and out randomly", but if you can discern a pattern that will help you divide and conquer.

You were right on, seemed to have been oxidation in the patchbay causing the issue. Thanks for the help!

 

[TwentyTrees]

Excellent! Glad you were able to find and fix the problem.

 

[CJ]

COVID has driven up Deóxit sales, amps stored for two years

 

[guy_4]

I recently ran into an issue with my Cl1b where audio fades in and out randomly. If I have a mic patched in and monitor the noise floor coming into the daw, after some time the signal will completley cut out. If I clap my hands or speak/ make noise into the mic the signal will return to the average noise floor. It’s as if there’s a gate randomly. Unit was working fine until this point, fresh tubes. Tested different cables as well. Side chain is also off. If I’m continuously running audio into the unit the level will drop about 5-10db and then return to normal. I’ve heard it could be a burnt fuse, just want to make sure it could be that before I take it apart.

Hello Dimitridask,

No burnt fuse here ! :-(

I suggest you to do a search for a recent thread on a Tubetech SMC-2B with similar issues, and the posts I did, based on my experience.

1/ let fresh air cool the inside of the chassis by removing the top panel, and 2/ replace all tubes sockets with high quality ceramic sockets with golden pins.

Best,
Guy