JJ Jr. Sound Cutting Out

Hi all,

New member here, and been gigging with my JJ Jr. for a few months now. Loving the sounds I can get from this amp!

This past weekend, partway through the first set, my JJ Jr. stopped producing sound. Power switch was still lit. Tubes still glowing. It went in and out a few times, then dead. Powered it down, and used a backup for the 2nd set. Decided to give it a another try during Set 3, powered it up, and it worked fine during set 3.

Tested the tubes tonight, and what I am calling V3 (the 12ax7 nearest to the power tubes, which I am assuming is the phase inverter) tested bad for Triode #1.

Some questions:
1. Would a bad V3 potentially cause the problems described above?
2. What else should I look at? I am reluctant to pull the chassis as I don't want to void the warranty. But I need to minimize the risk of a repeat offense.
3. What tube brands are recommended for this tube position?

Thanks in advance!

Throw a new tube in there and you should be good to go. Sovtek LPS are great PI tubes. You won’t void your warranty by pulling the chassis either.

Thanks LP Freak!

I’ll definitely look into the Soviet LPS. I had some 12AX7’s lying around (Millard, Electro-Harmonix, JJ, and non-specific Chinese). I threw the EH in there for now. Rehearsal is tomorrow, so I’ll see if anything else causes problems. And if I don’t like the EH, I can swap some others until I can get a Sovtek.

KY91C2":gwcs360u said:

Thanks LP Freak!

I’ll definitely look into the Soviet LPS. I had some 12AX7’s lying around (Millard, Electro-Harmonix, JJ, and non-specific Chinese). I threw the EH in there for now. Rehearsal is tomorrow, so I’ll see if anything else causes problems. And if I don’t like the EH, I can swap some others until I can get a Sovtek.

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To be honest you probably won’t hear much difference between brands in the PI but if the tube is bad definitely change it.