Nitro Bias and Tubes/Power (50w/100w) Question

311splawndude said:
Correct.
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Thank you. I'll look at removing them.

Just seeking clarification, when taking the 2 outter tubes out, I have to drop the OHMS in half. Is it that the ohms double up when removing 2 tubes? My cabinet is 16ohms (2x8ohms speakers in series)
 
Bash_Man said:
Thank you. I'll look at removing them.

Just seeking clarification, when taking the 2 outter tubes out, I have to drop the OHMS in half. Is it that the ohms double up when removing 2 tubes? My cabinet is 16ohms (2x8ohms speakers in series)
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Yes, if you want to do that long term then set amp to half power, remove outer 2 tubes, drop the ohms in half, and rebias the amp at that set up.

So if you are normally at 100 watts in full power and matched to a 16 ohm cab, you will now be mismatched at 8 ohms but it won't hurt anything.

If it was a 16 ohm amp load into an 8 ohm cabinet I would be more worried but it wouldn't bother me - at least with my Splawn or my Mesa.

The explanation is be beyond my ability but it has to do with the primary and secondary windings in the output transformer and how they handle loads and such. There are some cool diagrams of this out on the web if you want to geek out on it but I have no electrical engineering background so most of it is pretty foreign to me.
 
311splawndude said:
Yes, if you want to do that long term then set amp to half power, remove outer 2 tubes, drop the ohms in half, and rebias the amp at that set up.

So if you are normally at 100 watts in full power and matched to a 16 ohm cab, you will now be mismatched at 8 ohms but it won't hurt anything.

If it was a 16 ohm amp load into an 8 ohm cabinet I would be more worried but it wouldn't bother me - at least with my Splawn or my Mesa.

The explanation is be beyond my ability but it has to do with the primary and secondary windings in the output transformer and how they handle loads and such. There are some cool diagrams of this out on the web if you want to geek out on it but I have no electrical engineering background so most of it is pretty foreign to me.
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Thanks splawndude.. appriciate the your time responding.
 
so here's another question.. if I wanted to leave things as they are in 50watts mode and not remove any tubes from the outer sockets. can I just put in 2 of the older EL34s that I took out of those sockets? of course leave the amp in 50watts mode.

thanks
 
I think technically you can do that with no problem. The 'heaters' for those two tubes will be active. I guess that tells me that at least 2 pins from each tube would be actively passing current. So although that shouldn't affect the tone or anything else, it would unnecessarily wear down those 2 tubes over time. So I guess the question is, if you planned on staying in 50w mode most of the time, why would you leave them in?
 
311splawndude said:
I think technically you can do that with no problem. The 'heaters' for those two tubes will be active. I guess that tells me that at least 2 pins from each tube would be actively passing current. So although that shouldn't affect the tone or anything else, it would unnecessarily wear down those 2 tubes over time. So I guess the question is, if you planned on staying in 50w mode most of the time, why would you leave them in?
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Just in case I forget that I had removed 2 tubes and put the OHMS dial back in the cabinet matching setting.. or someone else plugs my amp into a cabinet and changes the OHMS dial to match their cab. also avoid dirt from going into the sockets.
 
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