"opcom" wrote in message
...
My Bogen MO-200 came with no tubes. (basically eight 8417's, driving two
parallel connected transformers for 200W)

8417 are expensive. I modified the bias supply for 50V, and put an
adjustment for each tube, and stuck 6550's in it. 6CA7's also work fine. I
split the amp into two 100W channels and put 6GH8's in the driver sockets,
with mods.

Mine does have a 1.0uF/100V plastic cap from filament to ground. too new
to be original. Never thought about it.

Aha! Finally, some corroberation and vindication for my
amplifier-desecration.

Some late-breaking info, I just know you were all waiting breathlessly for
this-- The two power-supply filter
capacitors turned out to be a bit down in capacity, about 30% down. I
suspect this contributed to the
problems. Still, it's a pretty marginal design that depends on capacitors
at exactly 100% strength.
And they were tiny to begin with-- two 40uf's in series! Plenty of room for
bigger ones, but noooo,
Bogen saved every penny they could. Maybe they were burdened with the cost
of the rather large output
trannies and had to pinch pennies in other places? Just a random surmise.


Regards,

George