Re: EL34 -> 6V6


"jh" <jh-audiop_NOSPAM@xxxxxxxxxxx> wrote in message
news:fe3ati$t6t$01$1@xxxxxxxxxxxxxxxxxxxx
Sorry Gil, but i bet you have not tried it...

gil schrieb:
While possible from a technical perspective, I don't think it will give
you the desired result. To do the proper conversion, you should change
to output transformer along with some of the "small parts" in the power
tube circuit. It probably isn't worth the effort of the cost. The amp
will still be loud and it will be a different amp.

not needed if you have an impedance selector; the only thing you should
consider before the "mod" is the plate voltage. If it is lower than
450-470V, you can get the JJ6V6S, fit some screen resistors and you´re
ready to go. Many times it´s even plug and play -and- completely
reversible.


One of the primary problems is that the 6V6 will need about half the
bias voltage of the EL-34.

???
the 6V6 and the EL34 have almost the same "bias expectations" in fixed
bias mode. Cathode biased is a different story.


The phase inverter/driver will have too
much gain for the 6V6 and can easily drive the grid of the 6V6
positive. A tweak of the drive voltage from the phase inverter should
also be considered.

Try it in an old 50W Marshall with low plate voltage. You will *not* be
dissapointed. But you have to re-match the impedances to make it sound
good. 8 ohm output selection into 16ohm cab.

regards

Jochen


I'm about to try this myself, using a JTM-45 clone head with B+ lowered to
410Vdc. I'm modding the bias circuit today, installing a 15K trim pot for
the bias range resistor to get the bias voltage down from that required of
the KT66's in there now.


.

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