I suppose it's possible the rectifier vacuum tube had a slow vacuum leak, and the filament burned up, or maybe it was long beyond it's usable life and the filament gave up on its own?
Did you confirm with a multimeter that the filament of the 5U4 which you removed was open?
Don Resor
-----Original Message----- From: Nigel Pugh via Jukebox-list jukebox-list@lists.netlojix.com Sent: Tuesday, June 11, 2024 10:16 PM To: David Breneman via Jukebox-list jukebox-list@lists.netlojix.com; Tony Miklos tonysjukeboxrepair@gmail.com Cc: David Breneman david_breneman@yahoo.com; Nigel Pugh pughn@npsyssoft.force9.co.uk Subject: [Jukebox-list] Re: 5U4GB and sound
I was only curious about the solid state rectifier alternative, as the tube amps in the Rock Ola tempos use solid state rectification so it must have been an alternative design choice at the time.
My main query/thoughts was the change in sound clarity, and intrigued why the previous 5U4G tube stopped working completely. Worked Saturday, dead Sunday. No degradation, just stopped.
Nigel, uk
On 11 Jun 2024 at 20:08, David Breneman via Jukebox-list
jukebox-list@lists.netlojix.com wrote:
On Tuesday, June 11, 2024 at 11:32:53 AM PDT, Nigel Pugh via Jukebox-list
jukebox-list@lists.netlojix.com wrote:
I'm assuming that the low output had an impact on the performance of
the power amp as a whole, > and the result was a woolly sound a bit like a worn out stylus. I've googled about, as I'm curious, > but not a lot of accurate info, and mostly guitar amp related.
Is this a common phonomenon when a rectifier tube has low output ? I'm
just curious..
Low output or gassy, a bad 5U4 will definitely make the amp sound more or
less awful.
I also saw solid state replacements but then read that the voltage drop
is much less, so amp > mods would be needed, and the warm up of tubes would mean the output DC would be initially > high, and not suitable for some amps.
What would be the reason for using a kludgey solid state replacement?
Almost every electronicdevice with tubes uses a 5U4 rectifier. They will continue to be available maybe forever.
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