Re: Battery bias directly to grid

In article <1129479453.815805.139670@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
"Andre Jute" <fiultra@xxxxxxxxx> wrote:

> I've posted a circuit for discussion at:
>
> http://members.lycos.co.uk/fiultra/Discussion%20Circuits.htm
>
> What are the implications of this circuit?
>
> What, theoretically, makes it better than the standard battery bias
> application in the cathode circuit?
>
> Will the batteries charge as efficiently in this position as in the
> cathode circuit; what are the effects of the resistors topping and
> tailing the battery set?
>
> What are this circuit's dangers?
>
> Are there alternatives that work better or are safer?
>
> Andre Jute



I note that the circuit you're describing is quite similar to an amp
design you have published on your website, the Type 39, Series VI "The
Tradition":

http://members.lycos.co.uk/fiultra/T39-KISS-300B-Ultrafi-crct.jpg

I assume you've actually built this circuit and tried it, so you should
know that rather then the circuit *charging* the batteries, they will
eventually be *discharged* by the input attenuator, especially in low
gain settings. You are also sending dc out the input jack to the
preceding piece of gear, which, in the case of a transformered output
circuit, will discharge the batteries at *high* gain settings.

Changing the gain setting will also tend to send a transient pulse into
your speakers.

If you're going to use this topology, you'll need to bite the bullet and
use a cap between the pot and the batteries/grid.

-bruce seifried
.

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