Sunn Model T reissue biasing question

[Especially Craig]

If I were to pull the 2 outer 6L6 power tubes on my Sunn Model T reissue, I plan to set the impedance tap to 8 ohm into a 16 ohm speaker load. Do I need to change the bias readings as well for ? The bias test points and adjustments ask for 60mVDC and balance at 0. Will this remain the same? My guess is that it would, since I don't need to adjust these settings when choosing between the "arena" and "club" power settings. I'd love your input. Thank you.

[Isaac]

I'm not familiar with the circuitry on that particular amp, but in general, no, the bias wouldn't be affected. You are correct about the impedance changes.

Do you know that pulling half of the power tubes reduces the power output by only about 3dB? That's not a big change. At a show last year, my bass amp fell over and one of the power tubes broke. I pulled its mate and played the show on half power for that night. The next night I added two tubes back in. There was very little difference. The second night, the sound seemed slightly fuller. In other words, a small difference in tone, but no significant difference in volume.

[Especially Craig]

Thanks a ton, Isaac. Great information. I imagine I'll leave things as they are. If I remember correctly, the reissue was very very similar to the Fender "Red Knob." I really love this amp, though I know Sunn purists look at it sideways. It sure makes me pick up my guitar and play. Thanks again!!

[Walt-Dogg]

Why would you want to do that? You can just switch the flip switch on the back from "arena" to "club" for 25 watts output instead of 100. Which is a much more noticeable difference than 50 watts and 100 watts dB-wise.

[Isaac]

OTOH, if he were to pull the tubes, it'd be 50w and 12.5w.

[Walt-Dogg]

True. But not all amps work properly after pulling a pair of power tubes.

[Isaac]

Especially those with only one pair!