6N1P CF with 300V B+

[mashaffer]

Is there any danger of turn on/off transients damaging a 6N1P cathode follower using a b+ of 300V as long as the quiescent state does not exceed the 250V Va rating?

 

[piano3]

No; sometimes the maximum rating is given as 300V anyway.

 

[6A3sUMMER]

If the circuit has something special or unusual that causes the cathode voltage to go higher than the maximum rated cathode to filament voltage, that could cause problems.

Please post a complete circuit diagram.

 

[mashaffer]

I don't think there is anything special. I plan to elevate heaters a bit. PS and interstage decoupling not worked out yet but the basic circuit shown below.

I could use an AU7 in that spot but unlike the other possitions the simulation indicates somewhat flatter response through the tone control circuits.

Another thing I am not sure of is how much of a disadvantage there is in both channels sharing a single bottle at the input stage. I could try using an AX7 follower to drive the infrasonic filter or adding another bottle and using paralleled AX7 sections in the input stage.

 

[6A3sUMMER]

The 6N1P grid is at +150V. With the cathode 25k Ohms to ground, there will be 6mA and the bias will be 1.5V, so the cathode will be at about +151.5V. The 6N1P maximum Cathode to Filament rating is + / - 100V. You will have to elevate the filament of the 6N1P.

 

[mashaffer]

Thank you. I was planning to put heaters at about 80V.