Problem running EL 34's in my clone

[HeeBGB]

Hi guys,

I am having a problem running 34's in my Express clone. When I am pushing the amp hard I get this crackle but only on higher pitched notes. Like the G B and High E strings above the 5th fret. The noise is on the leading edge of the notes and usually happens when I am picking hard. I have found that putting a 12AT7 or 12AU7 in V1 or V3 solves the problem. It does not happen when I am running 6V6's. I first noticed it on start-up when I was using new production EL34's. I switched to NOS 34's and the problem seemed to subside but now it's back. I haven't tried an AT7 or AU7 in V2 yet but I assume it will also solve the problem.

My thoughts are that the signal into the power tubes is too hot and needs to be tamed a bit.

Questions are:

A)Does a 6V6 take a hotter input signal than a 34?

B) Does anyone have any suggestions about how to best go about losing some signal before the power tubes without changing the amp too much?

I REALLY love the amp with 34's and want to use the new production stuff but I don't want to change the amp too much!

Thanks

Greg

[HiGain]

Interesting. My amp was doing the same thing, but with 6V6 and EL34 tubes. I traced it down to vibrating parts around the bright switch. I found I could induce the crackle by tapping the chassis hard around the switch, which led me to think it was a volume/vibration issue.

Jake