Amp comparison, audio clips!

[Carbia]

Actually, the tube runs better with 100k than 220k, not about the sound, about the tube function. Maybe the sound is better with 470k (I haven't tried). But I've tried 100k instead of 220k and I didn't notice any sound change and the tube lasts more.

[joey]

Actually, the tube runs better with 100k than 220k, not about the sound, about the tube function. Maybe the sound is better with 470k (I haven't tried). But I've tried 100k instead of 220k and I didn't notice any sound change and the tube lasts more.

Only power valves its coupled to for the reason one page back. Any value is fine so long as it doesn't breech the maximum rg1 value stated on the data sheet for the bias supply arrangement. (Fixed or cathode)

[Carbia]

I read that on the Tone-Lizard website:

At point #1 we see the bias-feed resistors. Usually these are 220K for EL34 output tubes, and 150K for 6550 output tubes. I lower both resistors, regardless of tube type, to 100K. This keeps the tubes on a 'shorter leash', and does promote long life. The theory behind this move is that the chance for the output tubes to draw grid current at high volumes is reduced.

[joey]

I read that on the Tone-Lizard website:

At point #1 we see the bias-feed resistors. Usually these are 220K for EL34 output tubes, and 150K for 6550 output tubes. I lower both resistors, regardless of tube type, to 100K. This keeps the tubes on a 'shorter leash', and does promote long life. The theory behind this move is that the chance for the output tubes to draw grid current at high volumes is reduced.

Yeah, This the same mechanism mentioned earlier, although the tone lizard explanation as to why is a little misled, and the terminology is a little wonky - there is no such thing as a bias feed resistor, they are just grid loads, like every other grid load in the amp, only tied to a negative voltage.

For EL34 Rlg1 is quoted a safe max of 500k to 700k depending on operation class and bias configuration. This indicates that their grids are not as leaky as some valves like a 6l6 for example.

[Carbia]

Ok, thank you for the explanation!