Could someone take a look at this circuit and explain the biasing arrangement of the 6AU6 tubes.
Specifically what is the purpose of the 330k resistors between the 1 MOhm Rg resistor and the 1800 Ohm Rk biasing the cathode.
The fact there is even a resistor between them is confusing me.
Thanks in advance.
Link: http://www.oswaldsmillaudio.com/images/rca museum pics/archive pdf's/SP20 Amp Manual.pdf
Specifically what is the purpose of the 330k resistors between the 1 MOhm Rg resistor and the 1800 Ohm Rk biasing the cathode.
The fact there is even a resistor between them is confusing me.
Thanks in advance.
Link: http://www.oswaldsmillaudio.com/images/rca museum pics/archive pdf's/SP20 Amp Manual.pdf
I think this question came up in another thread a few months ago. Did you search?
The cathode resistor, presumably used for degeneration, generates more voltage than is required for valve bias so the grid is attached to a potential divider formed by the 330k and 1M.
Most circuits either ground the grid (for DC) or pull it up to a significant positive value. This circuit does not, it pulls it up just a small amount, so it looks strange at first sight.
The cathode resistor, presumably used for degeneration, generates more voltage than is required for valve bias so the grid is attached to a potential divider formed by the 330k and 1M.
Most circuits either ground the grid (for DC) or pull it up to a significant positive value. This circuit does not, it pulls it up just a small amount, so it looks strange at first sight.
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