• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Secondary voltage for heaters

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pengboon

Member
Joined 2005
The local audio store adviced me to get a little higher windings, i.e. 7.0V for 6.3V filaments to account for diode drop when DC rectifying. It sounds reasonable to me, but why is it I always see schematics stating 6.3V regardless of DC or AC? Am I missing something or...?

thx! :)
 
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Sherman

Member
Joined 2004
The schematics are correct, 6.3V whether AC or DC. Are you planning on rectifying the voltage to the heaters? Except in the case of a phono stage it really isn't necessary.

If you are planning on DC heaters what type of rectifier are you going to use? If you are using SS diodes or a SS bridge your rectified voltage from 6.3VAC will be higher than 6.3V. Remember the 6.3VAC is RMS. Peak to peak it is higher. Rectifying that voltage using solid state bridge rectification will result in 6.3 x 1.4 volts DC.
 
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Dominique_free

Member
Joined 2005
With AC, you must know the total current and use it as nominal current for the transformer.

With DC, it depend also of the topology you want to use, and you have to calculate it. As a rule, higher output voltage from the transformer mean at it would be easier to get a clean DC but with more power dissipation on the alimentation.
 
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