6L6GC in rectifier position for Super Reverb?

[singing6string]

Hi guys, I recently purchased a 1970 Fender Super Reverb. I just had a look at it & was about to change the rectifier tube with a NOS 5U4GB one I have bought & realised it is a Triumph branded 6L6GC. On the tube chart on the amp it calls for a 5U4GB in the rectifier position (this has been hand written... not sure if it came from the Fender factory like that or not). Will putting a 5U4GB in there damage my amp? Could it be possible that the previous owner had it modified to take a 6L6GC in the rectifier position? Any one ever heard of this? Any help would be appreciated.

[SatelliteAmps]

A 6L6GC is not a rectifier tube. It has a completely different pinout, and the amp would not function if you tried to use a 6L6 in the rectifier position. Chances are, the tube is in the wrong socket. Check the other sockets to see if the rectifier was put into a different socket by mistake. Either way, amp won't work with e 6L6 in the rectifier slot.

[singing6string]

I know that the 6L6GC is not a rectifier tube & thats why I'm asking why it has been placed in this position by either the prevoius owner or an amp tech. The amp works fine with the 6L6GC in the rectifier tube position (far left if looking at the rear of the amp). Maybe the tube is branded wrong? The tube has a pinout combination of 2pins & 4 pins if that helps.

[John Ward]

Maybe the amp has a solid state rectifier mod and the rectifier tube socket is not in use. Try pulling the rectifier tube to see if the amp runs without it.

[Swarty]

Maybe the amp has a solid state rectifier mod and the rectifier tube socket is not in use. Try pulling the rectifier tube to see if the amp runs without it.


+1. This is the only way it could work. Good chance the PT was replaced and there was no 5V tap.

[Rosewood]

I would open this amp up to make sure of what I was working with.

[VacuumVoodoo]

Well, there's another, although remote possibility. 6L6 tube used as a pass element in a voltage regulator on B+. Perhaps someone tried to audiofoolize it?

[Rosewood]

audiofoolize??:dunno

[jawjatek]

Take the upper rear panel off (4 screws). Looking at the back of the amp on the left side, there should be 3 octal sockets. The leftmost octal socket is the rectifier socket. You probably can't see it too well with the panel on.

Either that or your amp has been "modded". Yikes! :barf

[SatelliteAmps]

I just want to make sure I understand. Your amp has THREE 6L6's? If there are only two, then you have a solid state rectifier plug in. If you have three 6L6's, then something is dramatically altered on your amplifier.

If you only have two 6L6's then there has to be either a solid state plugin or a bunch of diodes soldered inside the amp to create a solid state rectifier. If it is a plug in unit, then you can swap it for the 5U4GB and check the bias and all that. If it's soldered you will have to remove all of it before being able to use a tube rectifier.

If it has a replaced PT, that is a different issue alltogether.

[singing6string]

Thanks for your help guys keep it coming. It sounds like I need to open it up & have a look at the guts to see if there has been any mods. I will try to get to it in the next few days & give an update.

[RedMan]

It's probably a spare in case one goes out on a gig. Most likely 2 diodes inside.

[SatelliteAmps]

So, does it have two or three 6L6's in it?

[Rosewood]

Open and take us a picture, it's driving me crazy not knowing.

[donnievaz]

Does the 6L6 in the rectifier slot glow while the amp is running?

[bigkahuna2u]

weird!

[Swarty]

it's probably a spare in case one goes out on a gig. Most likely 2 diodes inside.

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