Rustling sound during warmup

[Stych]

Hi all.  In inherited a Carvin Legacy that had a few issues, mostly fixed now.  The one thing that it's still doing is making a rustling sound when it warms up OR when it comes off standby.  I've swapped out all the preamp tubes, with no change EXCEPT that with V5 (the PI) removed, it doesn't make any noise.  The reverb isn't attached at the moment, and I've jumpered the effects loop, with no change.  Does this sound like anything familiar to anyone?  Much thanks, and have a great day.

[terminalgs]

Hi all.  In inherited a Carvin Legacy that had a few issues, mostly fixed now.  The one thing that it's still doing is making a rustling sound when it warms up OR when it comes off standby.  I've swapped out all the preamp tubes, with no change EXCEPT that with V5 (the PI) removed, it doesn't make any noise.  The reverb isn't attached at the moment, and I've jumpered the effects loop, with no change.  Does this sound like anything familiar to anyone?  Much thanks, and have a great day.

possibly cathode by-pass caps.  you could lift the + side of the caps to check.   


Also, you might narrow it down to a section of the circuit by testing for the noise with volume controls (including reverb level) turned down, or (one at a time) volume control turned up.


I don't know anything about Carvins, so this general advice.

[jojokeo]

Check/replace your load resistors and/or soldering contacts there. The reason for quietness after the tube is removed is because there's no current flowing through them. It is also possible it could be an earlier tube's load resistor(s)/contacts because the pi interrupts the signal flowing down stream to the power tubes.

[Stych]

Great points, on both posts.  I leave town for work, so I hope I get time to try everything out before I go.  I haven't done a full test with different settings, but at first blush, it doesn't seem to make a difference, but surely worth a try.  The Carvin topology on these is pretty straight forward.  I'm mostly used to old Marshall and Fender tweed stuff, so the effects loop, reverb, etc make these a little different, and the tone stacks are different as well, but for the most part it's easy enough to follow.  A very good schematic was available online, so I hope to make some progress shortly.  I already re-flowed some pretty jive ass solder joints, so maybe it's just more of the same...  Thanks again, and with patience I'll let you know what I find.

Stych