What is the voltage To bias a marantz 8b?


I have a marantz 8b and the bias meter doesn't work, I am looking to bias my output tubes and want to know what voltage is appropriate .... can anyone help me answer this question?
kellymack
Thank you, that’s pretty much what I’ve been doing. I using some old tele’s and just wanted to make sure I don’t have too
much juice on them
Adjust both output tube cathode current to 50mA and you will get 0.68V across cathode resistor.
Great find, @imhififan That looks like an excellent, easy to use, and safe to use solution.

I believe it will provide results which are **slightly** less accurate than the original meter would have provided, because the cathode current that is measured will take into account screen grid current as well as the plate current which is measured by the original meter. But I suspect the resulting inaccuracy will be small.

The one caution I would cite for the OP, if he purchases that device, is that if the tubes are removed shortly after the amp is powered down he should be sure that his fingers do not come into contact with the pins of the tubes while they are still partially in their sockets. Some of those pins will have potentially lethal voltages on them for some amount of time after the amp is powered down, as long as the pins are making contact with the socket.

Best regards,
-- Al
The one caution I would cite for the OP, if he purchases that device, is that if the tubes are removed shortly after the amp is powered down he should be sure that his fingers do not come into contact with the pins of the tubes while they are still partially in their sockets. Some of those pins will have potentially lethal voltages on them for some amount of time after the amp is powered down, as long as the pins are making contact with the socket.
Add a DPDT switch in a small plastic enclosure closed to both tube socket adapter can solve the problem, if the meters are not in use, short the red and black wires by the DPDT switch. So no need to remove the output tubes and tube socket adapter.