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Think this console pull...

I built the EFB circuit from the Maggy 9302 thread, and realized its meant for both channels, 4 tubes... I have a mono amp, so only 2 tubes,,, so I'm guessing the caps and resistors may need to be adjusted, correct? Thought I better ask before burning it or the amp up!!
 

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knockbill said:
I built the EFB circuit from the Maggy 9302 thread, and realized its meant for both channels, 4 tubes... I have a mono amp, so only 2 tubes,,, so I'm guessing the caps and resistors may need to be adjusted, correct? Thought I better ask before burning it or the amp up!!
Click to expand...

Well, I tried it and it works fine,,, I can only get 360VDC B+, so its not optimal on this amp... gotta search for info on using it for 6L6s, now!!
Thanks to Dave for the circuit...
 
I don't believe its critical whether its running 2 tubes or 4. The regulator provides a fixed voltage mostly unrelated to the tube load.
 
gadget73 said:
I don't believe its critical whether its running 2 tubes or 4. The regulator provides a fixed voltage mostly unrelated to the tube load.
Click to expand...
Thanks,, seems its OK as is... Was it the same EFB that you used in your Bogen 100? Was thinking of trying in my Challenger/Bogen, running 6L6s now...
 
As I understand it, there are basically 2 versions. One is for cathode bias setups, the other is for fixed bias. The Bogen MO-100a is the fixed bias rig, the Magnavox 9300 runs the cathode version. Dave was kind enough to post the schematics for both so you can see how it works.

There is another one that implements a screen voltage regulator, but I haven't ever looked into that version.
 
Thanks, I'll see if I can find the other schematic, maybe for the Dynaco kits...
I was told they wouldn't be effective on 6L6 family, tho...
 
I believe he posted schematics of the one with the screen regulator in either his re-work of the Fisher 400, or maybe his SA-100 clone project.
 
I'll look and see,,, I just wanted to see if I could get it to work in a 6BQ5 amp, which it did... I took it back out... Was reading his original write up about developing it for the Dynaco amps on Tronola site... Seems it will work OK for 6V6s,,, I may try it in a Maggy 185 I recapped, but is mainly stock... not sure where to set it, tho...
 
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