by erichayes » Sat Oct 30, 2004 9:16 pm
Hi All,
Norris, the easiest way to get around the base wiring differences on the 7591 is to use chassis-mount sockets with flying leads to the circuit board. As far as electrical compatability goes, the bias voltage or cathode resistors, depending on which bias system you choose, will have to be altered to accomodate the tube's spec's. And, even though the 7591 is rated at 550 volts max on the plate, I wouldn't run them with more than 400 volts in fixed bias mode (but that's me).
Now that New Sensor and someone else (JJ?) have come out with new stock 7591s at a reasonable price, we're no longer held hostage by the Mac 225 tube hoarders who pulled a Hunt Brothers on the NOS 7591 market.
This is what DIY is all about.
Eric in the Jefferson State