Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: SILVERGUN on June 20, 2013, 07:55:56 am
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When using a 12.6 VCT xfmr to run the filaments in my power tubes, is this a correct wiring scheme to keep the phasing correct?
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Is that even an OK application?
In a 12VCT xfmr that is rated at 3amps, would each 6.3v tap each carry 3 amps as well?
Would it make more sense to just do this?
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"In a 12VCT xfmr that is rated at 3amps, would each 6.3v tap each carry 3 amps as well?"
Yes.
You could try the "one each side" scheme. It runs counter to the idea that the tubes reject hum due to their push-pull configuration. I myself would think it would cause hum, and one way might cause a lot more hum than the other.
I am sort of mentally dealing with this now as I am pondering converting a Conn organ chassis to a princeton or a deluxe...fairly vanilla. The PT has a 12.6 volt CT transformer. But that whole issue was answered for me because the power tubes turned out be 12V6, not 6V6...I did not notice that when I bought the organ......so that's that. Run the 12AX7's off 12 volts, run the outputs off 12 volts.
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Why don't connect the CT to ground and the filament of the Power Tubes simply in series ?
The Power Tubes grid are pushed by signals higher than those present in the preamp section
this is the reason why you have no humm problems having the Power Tubes filament in series
K
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Both diagrams above are bothering me because there is no ground reference. It appears that either diagram will light the filaments, but a ground reference is considered necessary for hum rejection. See: http://www.valvewizard.co.uk/heater.html (http://www.valvewizard.co.uk/heater.html)
This is a long-winded way of saying that I agree with kagliostro.
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... is this a correct wiring scheme to keep the phasing correct?
"Filament phasing" in my opinion is complete B.S. I say that cause I've tried both ways and it has made no difference in any amp I've built.