SET Asylum

RE: Recommend driver for SE KT88

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This Post Has Been Edited by the Author

In Reply to: RE: Recommend driver for SE KT88 posted by Paul Joppa on September 14, 2023 at 08:28:32

I might add a few bits here-- this is
not to be taken as advice to any builder, but rather these
are impirical observations only, decided upon by listening to
the best system wiring, source components, and speakers.
So please consider these ideas as not mathematically provable,
but relevant to good musical enjoyment:
The SE- KT-88 has continued to be my go-to amp for
personal musical pleasures, because I just LIKE IT better
than anything I ever heard.. or have played with since.
Remember DeHaviland Electric? They built SE amps using
the 845 triode, and later a Russian designed higher
voltage DHT triode with more amp-factor than the 845. This
DHT tube was more popular with the buyers at the time.
The Lady in charge, who I won't mention here, got
curious and had her tech guy modify a Fisher 50-watt,
PUSH-PULL ULTRALINEAR amp for her. I believe they
succeeded in eliminating all feedback, but my memory
might not be correct here.
In any case, she loved it, and it became her go-to
amplifier.
There is something about a good pentode that simply speaks
music when operated in ultralinear mode. No, I can't
tell you what this is, but it is THE BEST sound I have
ever heard and for many years I did SE DHT triodes to
maximum sonic results.
My current KT-88 fave is a "pseudo-triode" 6E6P directly
connected to a KT-88 running ultralinear with a 2500 ohm
output transformer primary driving a (Altec design) 604
series driver in an approximately 11+ cubic foot cabinet,
that is a transmission-line design utilizing dual ports
that are symmetrical to each other, delivering very linear
bass response.
The speaker system is linear over the entire audio
range, and this feature makes it both spectacular and
musically pleasing with less listener fatigue and more
musical detail and dynamics than anything I've ever heard
or used. This makes it very telling of any and all amplifier
characteristics as far as altering music signals goes.
The 6E6P is run at about 15 ma. Plate and cathode voltages
were adjusted to get the KT-88 to operate at about 68ma,
with approximately 490 VDC on the KT-88 plate, with near
245 VDC on the cathode. This is because I always try to
get the cathode VDC at 50% of the voltage applied to the
plate. I find this more dynamic with lower distortions.
The KT-88 may very well be the most musically accurate
vacuum tube ever designed. I can't tell which ones of
the current crop are THE best, but I like the Russian
made "Gold Lion" copies, and the TAD (Tube Amp Doctor)-
Germany.
There is "something" about the KT-88 design that
SPEAKS NUSIC, linearity-be-damned.
Best advice is to find out WHY.
Thanks for listening to me! -Dennis-

Edits: 08/21/24

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