• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Tube turned black and rainbow. Cause?

My final comment to this thread would be if you want to hear how this amplifier is actually intended to sound I would not modify it at all, the Jadis stuff is interesting sonically speaking.

Sorry that my recollection of servicing them is not what it should be, but it's been 21 years since I last worked on one, and a lot of things have happened in the intervening years.

Just don't be too quick to give up.

The level of contradiction is epic in this thread so I'm going to bow out now. Good luck Mark!
 
i never ever used a bucking traffo, i design and built all of my traffos used in my projects....

there are other ways to lose some dc voltage is you want to, another way is added resistance at the secondary ac line to the rectifiers...

this and the dc resistance mods can be used alone or in tandem, there are many ways to skin a cat...

if you can post a schematic of the psu and dc resistance of the power traffo hv ac secondary, then more concrete suggestions are possible...

no one is stopping you if you want to use abucking traffo, it's your choice, but bear in mind that there are two ways you might end up with, one lower secondary ac and the other a higher hv ac, but this is not so catastrophic, just reverse the winding of the bucking and you are go...

in the end, your amp, your choice, do what you think you have the confidence of doing, this is after all DIY, where all ideas are welcome...
 
i never ever used a bucking traffo, i design and built all of my traffos used in my projects....

there are other ways to lose some dc voltage is you want to, another way is added resistance at the secondary ac line to the rectifiers...

this and the dc resistance mods can be used alone or in tandem, there are many ways to skin a cat...

if you can post a schematic of the psu and dc resistance of the power traffo hv ac secondary, then more concrete suggestions are possible...

no one is stopping you if you want to use abucking traffo, it's your choice, but bear in mind that there are two ways you might end up with, one lower secondary ac and the other a higher hv ac, but this is not so catastrophic, just reverse the winding of the bucking and you are go...

in the end, your amp, your choice, do what you think you have the confidence of doing, this is after all DIY, where all ideas are welcome...

I’ll have to think about this. I can post a schematic
 

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definitely R7, 4.7 can be increased....500ufd of filtering is huge...

if you can indicate the voltage readings on either side of 4.7 ohms, and see actual voltages...

now tell us how much voltage you want to lose....or what voltage you are comfortable with...

are the filament voltage reading within limits?

one disadvantage or reducing the primary voltage is you can end up with lower filament voltages...so all things need to be considered...
 
definitely R7, 4.7 can be increased....500ufd of filtering is huge...

if you can indicate the voltage readings on either side of 4.7 ohms, and see actual voltages...

now tell us how much voltage you want to lose....or what voltage you are comfortable with...

are the filament voltage reading within limits?

one disadvantage or reducing the primary voltage is you can end up with lower filament voltages...so all things need to be considered...

Thank you Tony. I have to open up the amp again to get all the readings. I’ve been playing it a little bit. I will try to do it this week. It’s a huge and heavy monster, not easy for me to handle...