5E3 Proluxe chiming

[passfan]

My new proluxe gets chimey when I hit certain notes. I've swapped out tubes to no avail and the only thing that does it is using an external cabinet and mechanically isolating my amp from it (I can't even set the amp on the cabinet). Once I do that I can go all the way to full volume with no chimeyness whatsoever. Do I have to isolate my chassis with any kind of damping from the cabinet or glue down the caps on the fiberboard? I can pretty much chopstick anything under the hood and make it do it , it's that sensitive.

[Tom Phillips]

If you "can pretty much chopstick anything under the hood and make it do it" then there is something there that you can eventually find and fix. Tubes aren't the only culprits. Caps and even coax wiring can be microphonic. If it's a cap then gluing everything down could potentially make make the problem worse or harder to find. I suggest you keep looking for the root cause rather than work on a cover up fix. Maybe give it a rest then poke around inside again later.
Regards,
Tom

[loudthud]

Poke around will the volume controls all the way down. If it still does it, that eliminates any component before the volume controls. Run the amp with the 2nd preamp tube removed. If it still does it, that eliminates a few more components.

[passfan]

I will try that loudthud and thanks for the vote of confidence Tom. If I recall corectly (I love misspelling that word) It doesn't do it with the volumes turned down. I will check these things out today.

[passfan]

Well I narrowed it down to the preamp stage and from there it turned out to be a 12AT7 which runs just fine in another amp (with not as much first stage gain). She is humming along sweet now and I love the sound wide open. Thanks guys

[Tom Phillips]

Glad you found the problem. Thanks for letting us know what you ultimately found.

This is a good troubleshooting lesson, i.e. after you have substituted a "known good part" you can't totally rule out that part. Then there is the situation where a combination of things are causing the symptoms.

Regards,
Tom