Re: Alan Dower Blumlein "garter" circuits now in triode mode EL34 P-P amp

In article <antse415gmbhqcpl3lm01v6av0baoed4sb@xxxxxxx>,
flipper <flipper@xxxxxxxx> wrote:

On Thu, 09 Oct 2008 08:17:24 -0500, John Byrns <byrnsj@xxxxxxxxxxxxx>
wrote:

In article
<dc9475d9-2f75-4b5a-a1f5-21efa88c7bd6@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
tubegarden <tubegarden@xxxxxxx> wrote:

Hi RATs!

Took me three and a half years to try eight resistors and four
capacitors :)

Doesn't meet the KISS principle, why use "eight resistors and four
capacitors"
when only one resistor and one capacitor will do the job?

The first task is, or should be, to define 'the job' and if current
balance is a part of it then the "one resistor and one capacitor"
doesn't do it.

Al's definition of the job seems to be first preventing "current imbalance in
the output transformer", because it "gobbles bandwidth and sensativity", and
secondly insuring that "it sounds wonderful". Presumably Al's point is that if
"current imbalance in the output transformer gobbles bandwidth" then it won't
sound so wonderful. While that seems reasonable, I'm not sure how gobbling
"sensativity", what ever that is, will keep an amplifier from sounding wonderful?

My requirements for the job are a little different than Al's. I start with the
same requirement that the amplifier sound wonderful, however I don't feel that
current balance in the output transformer is a necessary condition for an
amplifier to sound wonderful, so I don't make current balance a requirement of
the job. Secondly for numerous reasons I prefer simplicity, so I don't like
solutions that take extra parts to implement, KISS.

Presumably the problem with current imbalance in the output transformer is that
it can cause the transformer to saturate under some conditions, producing
distortion and restricting the power capability at low frequencies. An
alternate approach to the problem of current imbalance in the output transformer
is to use a simple circuit and deal with the current imbalance by over
specifying the output transformer so that saturation won't occur with a
reasonably balanced pair of output tubes. While this approach may cost a bit
more, it is only a hobby, and is harmonious with Al's maxim that "a penny saved
is a world lost".

--
Regards,

John Byrns

Surf my web pages at, http://fmamradios.com/
.

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