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(click photo to download schematic pdf - ~120kB)
I always wanted to do a small triode push pull amp.
Small means always
tubes with two systems in one envelope.
Because the European
Manufacturers decided to put only small
signal triode/power pentode
combinations (ECL - Family) in
one tube I had to look for US types.
They put triode/power triode systems in one tube.
After a short
inquiry on the web, I found the 6em7/6ea7 tube.
was integrated in almost every past made US TV.
Out of this
reason this tube
is reasonably easy to get in NOS/NIB versions today.
But due to the
high demand in the US itself and from
Asia, esp. Japan and Taiwan it's
costlier and costlier.
So it's remarkable only for laymen
that the schematic that I found came from Japan.
I didn't understand a
word written at the japanese web site,
but I found the original schematic
Unfortunately all the original links are broken in the meantime (Oct/04/2009).
The schematic was simple enough to fulfil the KISS principle, and
because I heard
various enthusiasm about the 6em7 sound, I decided to
give this amp a try.
The parts are from my desk (output trannies from a cannibalized K+H
from an ebay auction (trannie), from
bulb (choke), from TubeWorld (tubes),
from a Flea
cabinet is an old NEXTstation) and from Reichelt ("normal" devices).
I build this amp and it ran at first go.
It's a wonderful amp, which is
putting out 2x 8 Watts in a superb quality,
even with non superb
components (see above).
I can assure you that this amp has a superb
esp. if you have the fitting output trannies
in the depth of your tinker's universe.
As always: Feel free to contact
me if you have any questions, comments, suggestions etc.
The Web Site addresses from the mentioned suppliers can be found at the