I have a 380-0-380 powertransformer and a 6K6 OPT. Is it possible to make a GU50 PP amp with this stuff ? any guidelines ?
Hello Jaap,
have a look at this link: http://4.bp.blogspot.com/_2jaM4iF8Gz0/S_DHjlbLkBI/AAAAAAAAAKg/Gw7Y8vCZUSI/s1600/GU50+350v100ma.jpg
6k6 OPT seems pretty well for triode mode.
have a look at this link: http://4.bp.blogspot.com/_2jaM4iF8Gz0/S_DHjlbLkBI/AAAAAAAAAKg/Gw7Y8vCZUSI/s1600/GU50+350v100ma.jpg
6k6 OPT seems pretty well for triode mode.
The datasheet for the LS50 states 5k for pp pentode between 400&600V. 6k6 is close enough.
http://tdsl.duncanamps.com/sheets/ls50/ls50_3.gif
http://tdsl.duncanamps.com/sheets/ls50/ls50_3.gif
I have a 360 volt transformer gives about 470 volts, is this too high for triode GU50?
Just ordered 20 x GU 50.
Thanks
Phil
Just ordered 20 x GU 50.
Thanks
Phil
I'm pushing mine with 390 B+ in triode, 470 would be really pushing it. You can always lower the B+ by lowering the capacitance of the first filter capacitor before the choke. Put your power supply on Duncan amps PSUII and see what you get. Current for one pair of PP GU-50 should be between 100-140ma. Try putting in a 4uf 630 film cap as he first cap and see what you get at the GU-50. If you use a tube rectifier, you can use a 5U4 in place of a 5AR4 to lower the voltage 15-30 volts
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DeathRex.
Thanks; I will try about 370 to 390 volts; I have used the EL36 at 370 with the same transformers, from memory about 2UF cap before the Choke. Roughly How many watts in triode do you get with the GU 50?
Thanks
Phil
Thanks; I will try about 370 to 390 volts; I have used the EL36 at 370 with the same transformers, from memory about 2UF cap before the Choke. Roughly How many watts in triode do you get with the GU 50?
Thanks
Phil
My SE GU-50 is switchable between triode, UL, and pentode. My PP GU-50 is only pentode. I used anode to grid feedback (I think I got from Wavebourn) on the GU-50s, so I couldn't use triode too.
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