[John Stone]

On 7/14/10 8:37 PM, in article
, "Bret L"
wrote:

They didn't have cheap silicon diodes, so you needed tube rectifiers,
not only for HV but bias as well unless you wanted to use a battery.
And a relay to open if no bias voltage was there and bring in a
cathode resistor.


Um, ever hear of a selenium rectifier? Mac, early Marantz, Fisher, Dynaco,
etc all had 'em for bias and dc heater applications. Yeah, they wore out
after 10 years or so, but by then you had the silicon replacements.