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Gareth Magennis
 
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Default Fender "The Twin" Power resistor values?


"François Yves Le Gal" wrote in message
...
On Fri, 31 Mar 2006 14:11:35 +0100, "Gareth Magennis"
wrote:

Interestingly it has a set of Mesa 5881-6L6 tubes (STR 425). Are these
5881
or 6L6?!


They are neither.

In Mesa Boogie's parlance :

STR 425 = relabeled 6pi33C., a Russian equivalent of the 5881,
manufactured
by Reflektor and identical to the Sovtek-branded 5881WXT version. The
6pi33C
is quite a poor match with Fender Twin Reberb like circuits and iron BTW:
max output power is limited and tone if far from optimal.

STR 430 = Russian take of the 6L6GC, also manufactured by Reflektor and
identical to the Sovtek 6L6WXT+ version.

The Twin is designed around real 6L6GC's. When the 5881's die, you should
try some Svetlana SED (circle C logo - not the winged S, which are
rebadged
Sovetk's, again) 6L6GC's or the excellent Shuguang Chinese version under
the
TAD 6L6GC-STR moniker , which give some of the best results in this amp
type.




Glad you said that, the Svetlanas Circle C are what I use.





BTW, STR originally meant "Special Test Requirement". This label was only
applied to fully tested and graded tubes targeting critical applications.
It
doesn't mean the same nowadays and only designates tested and matched
tubes.

I understand 5881 cannot take the same plate voltage.


B+ is aournd 470 V in high power mode, with around - 60 V bias. the output
tubes see less than 410 V with around 40 ma of current, well into the SOA
of
a 6pi33C.






Thanks for the lesson, much appreciated.




Gareth