KT88/6550/EL34 SE Amplifier only pictures



KT88/6550/EL34 SE pictures for last model on Abr 2008
Just mounted components on chassis ,Driver is ECL82(6BM8)triode connection.
and cathode chorke drive.cathode of ECL82 connected with high inductance
chorke transformer(80H 10mA)and hot side directly conected to G1 of 6550.
bias is auto bias. limited current by LM 317.plate current can adjust proper
current ,this time choose 73mA and point of cathode of 6550/KT88 is around 38V
if do you have larger capability of power transformer please try to adjust
plate current and sound are changed depend on plate current value.
out put are 2 position swiched 8 and 6 ohm.
Audio Transformar are Touei Transformer Co Tokyo Japan.OPT-10S medium size
Audio Transformer.OPT-10SR model will be get soon from Touei Transformer Co.
OPT-10SR is with low cost black metal case so not necesary to use Transformer Cover.
( Note:in Japan many electrical replacementparts price are going up
around 20% from last year 2007.even Transformer too)if would like build one up
please use ECL82 is RDF NOS or mullard etc.new ECL82 does not get good sound.
I tried varios valves and sound is very fine.I thought better than 300B.
(Este Amplificador KT88/6550 SE suena mejor que 300B SE y 2A3 SE.que le parece!!!)
KT88 UL is just like 300B sound to get.do you believe ?
Tested : EL34 EH , EL34 Telefunken 1970 , 6550 EH, 6550 GE,6L6GC Svetrana,6L6GC Sovtec.
any way I will show you some pictures.



Push botton to see picture


: you can use KT77,EL34,KT88 instead of 6550


: you can see 5 tubes
: small SW for impedance change


limited current choke drive


Single Ended 6B4G Cathode Drive Amplifier

now I am introducing KT88 SE modificated 6B4G Single Ended Amplifier,
Power drive needed for 6B4G SE in generally.circuit is just same as 6550 SE.
skematic diagram is next


6B4G and 2A3 is Different Tube

many person said 2A3 and 6B4G are same valuve as a same charactor .
only different filament voltages and current but same thing more different between
them. Ig(grid current) is slightly more than 2A3 and output impedance is also slightly
high than 2A3(RCA).in generally 2A3 is 2.5Kohm but many case use 3.5K for 6B4G.
6B4G filamnt power 6.3W but 2A3 is 6.25 W for filament comsamption power.
Ig high so not suitable by penthode drive with CR coupling.
and actually 6B4G has 3 type of 6B4G. 6B4G (direct heating triode) and 6B4G(Indirect
heating with Penthode conected triode).some one said Indirect 6B4G is just like a
6L6GC triode mode and Sylvania 6B4G is Indirect valve.
really 6L6GC triode getting power around 3W.H type , Twin Plate Type and mono plate(New).
But 2A3 and 6B4G are same charactor Valuve in general.
6B4G mono plate EH is different valuve and over Spec.6A3 and 6B4G are same valuve only base is
different.you know 6C4C is same family of 6B4G but sometime 6C4C and 6B4G are same.
depend on date ,place of fabrication and manufacture.6A5G is indirect filament and
filment power is slightly more than 6B4G.
2A3 3.5 W 6B4G 3.2 W
real power is 4.5 W rms and I got Max power is 5.5 W rms.Valuve is 6C4C "S"Mark 1970
from Russia Made.feel better than 300B SE.if used U-808 Tango or XE-20 sound id
much better than small Touei OUTPUT(OPT-10S).Single ended amplifier needed more than
twice of real output power. 6C4C is same one of 6B4G Zaerix.very nice valuve.sometime
6B4G Zaerix is very expensive but 6C4C is inexpensive .but sound are same.
on 8th July 2008 from Sakura Chiba Japan.


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6C4C Data from tubes.ru

(up date 8th July 2008)this part sience 14th Apr 2008 from Sakura Chiba Japan

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