Jones's servo bias
On Dec 5, 4:44*pm, John L Stewart John.L.Stewart.
wrote:
Hi Ian & Others- Yeh, I'm back again after another 5 year stint in
hitech sales. But I guess for the last time at my age!
Kevin O'Connor is adventurous & perhaps does some things others may not
approve of. Thus a toroidal OPT in a guitar amp. No problem with servo
bias holding the lid down.
That might be hotly disputed by those who feel that a softly-
saturating OPT is a desirable tone option.
This one not as elegant as that found in the Brook, easily the best I've
seen in my very long career. It is unique & sure makes a lot of sense.
How else to get 30 Watts at low distortion out of a pair of 2A3's in
AB2?
I got interested in servo bias some time ago while doing my thing with
6AS7/6080 PP circuits. Some may remember the bootstrapped driver schemes
with & without the UL OPT. But the heat from the cathode bias resistors
under the chassis is a serious problem. So lets try somekind of servo
bias. Perhaps this coming Winter.
I've been busy on the bicycle (like Patrick), more than 4000 Km since
May 1st. And a lot of physical labor here on the acres. I would rather
be outside than slaving over a hot soldering iron!
I quite fancy a little rocket. Bradford is full of hills and dangerous
drivers with no insurance. Even walking is scary. I don't have room
for a helicopter.
For anyone who would like a complete schema of the Kevin O'Connor guitar
amp referenced email me direct as follows-
jh dot stewart at sympatico dot ca
I replaced Jones's clamp with O'Connor's. Perfect.
Gotta go now. Today its time to service the summer equipment & put it
away till Spring! And here is that easy to drive 6AS7/6080 amp for the
curious.
Summer equipment? In Europe, we have a fire in the sky controlled by
druids with henges. Every time the druids get locked up on drug
charges, the weather falls apart.
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Thanks. Interesting. I guess there's some maths that goes with the
weirdness? Like the load seen by, and output resistance of, the short-
tailed pair's anodes.
Ian
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