Fender blackface Vibrolux

[Pepe]

Hopefully nothing but pure bliss.

[laurie]

It was never glued... or at least improperly glued.

Interestingly, the other side is rock solid.
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20250501_065825.jpg (465.33 KiB) Viewed 119613 times

[laurie]

Cleaned the surfaces, drilled 3/8" (10mm) holes with a depth-controlled Forstner bit. Then glued and doweled. It will never move again...
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1964 vibrolux batten repair.jpg (400.39 KiB) Viewed 119593 times

[laurie]

And on it goes...

The rattle is gone!

But turned it on when the amp was fully back together and crackle, snap, pop, hummmmm. The same symptoms as when i thought the reverb driver tube had failed.

It wasn't the reverb driver tube. It appears that all the tube probelms I've been traking down - failed rectifier, failed reverb driver, failed reverb recovery... none of that was the actaul issue. The symptoms were conicident.

What has actually failed is one of the brand new mucho expensive power tubes.

So, back to some normal JJ's. Nowhere near as nice a break-up, but no issues either.

I'll be contacting my supplier to figure out what to do next about tubes, but for now the amp is fully functional.

[Pepe]

Oh, man!

[laurie]

Yeah. The JJ tubes work fine, but the amp has lost its vintage vibe. Just sounds like my hotrod deluxe.

I'll figure out how to get another set of vintage spec tubes and go from there.

[Pepe]

What an impact these tubes have!

[laurie]

I think I figured out what happened...

• Did the first lot of work, installed new vintage specification tubes.

• The broken socket on one of the power tubes caused the heater on that tube to be intermittent, causing an arc in the tube that damaged the tube (I've had that happen before with power tubes and a bad socket). Tube was damaged, not destroyed.

• As the power tube was sustaining the damage, that caused the vintage specification rectifier tube to arc and die.

• The modern spec replacement rectifier tube was strong enough to withstand whatever was happening. Or perhaps the original rectifier damage only occurred at the time of the initial fault.

• Replaced the power tube sockets and everything seemed OK. Until it wasn't.

• The damaged power tube had issues when reverb was kicked in, probably the additional signal? Making it look like the reverb circuit was at fault. There were faults in the reverb circuit, but the buzz/pop/hum was likely the messed up output tube.

• The damaged power tube eventually just failed. How do I know? At the end, when it was continuous buzz/pop/hum the damaged tube wasn't getting warm.

• New JJ tubes and everything works with no issues, but all the vintage spec tubes are now out of the amp.

Just dug out the tube tester and, yeah. One of the new vintage spec tubes has a short. CAD$100 for that pair down the drain. Bugger.

I think this explains why the amp is in pristine condition. It has probably been damaging tubes for years and it ended up being shoved into the corner of someone's basement. The output tubes that came with it were weirdly mismatched, and one of them had failed. Probably the last tubes someone put into the amp before they gave up.

[laurie]

I think I figured out what happened...

• Did the first lot of work, installed new vintage specification tubes.

• The broken socket on one of the power tubes caused the heater on that tube to be intermittent, causing an arc in the tube that damaged the tube (I've had that happen before with power tubes and a bad socket). Tube was damaged, not destroyed.

The lesson here is - on any old Fender amp, assume the Octal sockets are faulty until proven otherwise, and perhaps just change them anyway.

[laurie]

New vintage spec tubes are on the way.

After playing it for a while, I'm also going to chase down the hum. It is a vintage amp, but should be quieter. Likely either the heater lead-dress, a failing pre-amp tube, or the bias voltage not filtered quite enough.