by gtasound » Wed Jan 16, 2013 8:40 pm
Shannon,
first of thanks for the PSUDII simulation, I am still a little confused as to the use of this program, getting closer to understanding it.
At present I am running the Clementine amp with KT88 in triode mode with a 600vct PT, sounding absolutely excellent.
The only reason for the higher 700vct PT is to run the KT120 in a more optimized triode mode giving higher power in the range of 8-10
watts, just like the look of the big tube and was interested to build a new amp with this tube.
As for more power it is easy with your board to run in Ultra mode giving approx double the power in the range of 7-10 watts just adding
depending on what output tubes are being used, a 1k resistor to R27-R28 and remove R15-R16 triode connection, which is well thought
out and agree with the need for loop feedback in Ultra mode because of speaker damping factor which other designs by other people
seem to ignore, having experience with a SE KT88 pentode amp which was run in triode and pentode, pentode without feedback was
not good, very good in triode, your 2 stage design is much better, congrats for that.
Attached find my 600vct PDUDII simulation based on your 700vct simulation using the additional currrent sink, which I did not use before
but now understand why it is there, simulation seems to look good, actual measurements on the KT88 plate show 368v and all
heater voltages are right on have not checked the plate voltages on the 6sl7, which I understand should be around 300v.
Dieter
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- KT88_600vct_v1.zip
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