Dual Cathode Resistors - Quad Power Amp

[Dr Tony Balls]

Is there anything wrong with using two cathode resistors (and caps) in the power section of an amp? Specifically this is for a 4xEL84 amp, and each pair would get their own resistor like so:



Reasons for this would are 1) ability to use two smaller 5W resistors instead for one big 10W, and 2) you could have simple half power operation by just disconnecting the ground on one pair.

[cdemike]

No issues. Lots of amps use separate cathode resistors (e.g., Vox AC100). If the cathodes are fully bypassed as shown, there shouldn’t be a discernible sound difference aside from possible variation in the output tubes’ operating point because of differences in the actual values of the resistors due to tolerance or available resistor values.

[Dr Tony Balls]

Thanks. I figured as much but couldnt think if I had ever seen it before.