Stereo build- Mikael Abdellah's KT88 SE amp

[arold19]

I use this amplifier since a couple of year now with a low fillament voltage of 5.7V since the 6.3V specification... Do you think it is a good idea to correct that problem? First of all, my power transformer have 3 output of 6.3, I use one output for each tube! I have 119.5V from the wall... The DC output is 400V dc... When I try the 110V input (tap) of the transformer, I have 6.4V to the filament and 440V supply so. Can I run this amplifier at this high voltage without any problem? 6.4 is a little bit high? I can put resistor to drop that voltage? Can I add a resistor to drop to 400v?
Thank you!
It is a good idea to put 2 X 100 ohm resistor directly at the output of the power transformer?

 

[arold19]

 

[tim614]

Have you try a different rectifier like a 5r4

 

[arold19]

The 5u4 tube have about 44v drop and the 5R4 is 67V.... so I will loose about 23V. I think this will be perfect. Excellent Idea, I will order a new rectifier tube!
Thank you Tim614.

 

[arold19]

There a lot of 5R4 tube and I'm a bit confuse... 5R4GA, 5R4GB, 5R4GY ???
I reed that the max value for the input cap is 4uF for this rectifier?

Which one I can try?
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