Convert ultralinear Fender to standard output?

[Groover]

If one wanted to change an ultralinear '70s 2x6L6 amp to normal, non-ultralinear operation could it be done using the same (UL) OT?

I think you would have to add a choke?

[tedmich]

all that's entailed is capping off the 40% OT taps to allow the amp to be a straight "pentode" I'd use inner melt heatshrink and pinch the end closed when still hot on the 4 ends once cut. This will allow reconnection if you don't dig the big decrease in output. A big beefy DPST switch would let you try it out,

apexjr
but it would be noisy and dangerous

Oh I think chokes are a complete waste, although Fenders could use more filtering usually

[Groover]

but it would be noisy and dangerous

It would be noisy and dangerous to use a switch?

[fyl]

Could be with the amp on. No problemo if you switch when the amp is off.

[Groover]

all that's entailed is capping off the 40% OT taps to allow the amp to be a straight "pentode"

Wouldn't you have to connect the screens to some B+ voltage, rather than just disconnecting them from the tap on the transformer? Might need to go to a DPDT...

[JoeM]

Wouldn't you have to connect the screens to some B+ voltage, rather than just disconnecting them from the tap on the transformer? Might need to go to a DPDT...

Sure, otherwise it wont work at all.

What model Fender is this? I had a Super Reverb UL model years ago. (Bought it new). Needed a loud clean amp and it worked well for that. I dont know how easy it would be to convert to the earlier SF or BF circuit.

[Groover]

This is also regarding a UL Super Reverb

[JoeM]

This is also regarding a UL Super Reverb

Groover,

I see that you're in the L.A. area. Maybe you got my old one! Does the pull gain boost work on yours? Mine didnt when I purchased it, so a tech at the music store I worked at took all that crap out and maybe did some other tweeks - the amp didnt seem so 'brittle' afterwards.

[Groover]

No, I'm asking for a friend in the Bay Area.

[bajaman]

Oh I think chokes are a complete waste

Well I don't - it tightens up the bass response and improves the dynamics at high power levels and also the top end response is a lot clearer.
bajaman

[hasserl]

I'd try leaving the UL hooked up and just disconnecting the nfb before I went to the extreme of converting it to pentode operation.

[pdf64]

'if you don't dig the big decrease in output'
with the Fender 75, the power output is the same whether it's configured as UL or regular beam tetrode. No decrease in clean or overdriven power output with the screen to their own supply node.

[CitizenCain]

I'd try leaving the UL hooked up and just disconnecting the nfb before I went to the extreme of converting it to pentode operation.

+1