2A3 lightning show

jbrahen · 1379

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Offline jbrahen

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on: March 07, 2023, 04:50:41 PM
Hey fam,
Just switched on my Stereomour II and immediately a lightning show in the left 2A3 with some crackling in the left speaker. I switched it off immediately. I've only ever seen tube failures look like increasing yellow/red glow, so I thought maybe this was interesting and I should post about it? It really just looked like the inside of one of those orbs that makes your hair stand up when you touch it... just lightning. Could it be the tube has expired? They're the electro-harmonix that came with the kit. Everything has worked great until now... what could have changed? My goodness, I've been listening to this amp for almost 2 years already?!

Sadly I wont have time to test everything until this weekend. Man I hope nothing bad is broken.
Maybe it's time to burn money on these Shuguang black treasures everyone has raved about? Suggestions?

Josh B.


Offline Paul Birkeland

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Reply #1 on: March 08, 2023, 04:16:22 AM
I would run the amp with just the tube that didn't do that, test that channel, then power down the amp and move the good tube to the other channel and have another listen.

I suspect that the tube that got flashy will start to exhibit white tinges around the silver flashing inside the glass, which would indicate that the airtight seal has been compromised. 

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline jbrahen

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Reply #2 on: March 08, 2023, 11:40:47 AM
Thanks Paul! You're absolutely right, both channels work well with the non-flashy tube. Looks like it's time for a new tube. Must I purchase a matched pair? And I know there's a billion posts about tube rolling, but any quick recs for a tube that may be an upgrade from the electro harmonix? I love me some lush mids.

Josh B.


Offline Paul Birkeland

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Reply #3 on: March 08, 2023, 02:21:19 PM
I would just get a single EH and not worry too much about it. 

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline jbrahen

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Reply #4 on: March 08, 2023, 02:45:17 PM
Thanks Paul! I really appreciate you and all you do for this community.

Josh B.