Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: crashtm1 on November 07, 2015, 07:14:38 am
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I've got a Hammond PT 272HX
It's running 4-6V6 and 4-ax7
Looking at the amp draw, what number do I use?
5vct @ 3A
Or 6.3vct @ 8A ???
Considering 4-6L6.
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I've got a Hammond PT 272HX
It's running 4-6V6 and 4-ax7
Looking at the amp draw, what number do I use?
5vct @ 3A
Or 6.3vct @ 8A ???
Considering 4-6L6.
I'm not sure what the question means??? But, the 6V6s and 12AX7s must be connected to the 6.3V winding. (BTW, the drawing shows that it's rated for 6A, not 8A.) The 5V winding would only be used for a 5V rectifier tube such as 5U4, 5Y3, 5AR4/GZ34, etc.
That 6V @ 6A winding will easily/safely run four 6L6s and four 12AX7s.
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Each 6L6 filament draws 900 mA (0.9A) @ 6.3 VAC, so 4 of them draw 3.6A
Each 12AX7 draws 300 mA @ 6.3 VAC, so four of them draw 1.2A.
So total filament draw will be 4.8A. Therefore, the PT has enough current to power the filaments.
the 5VAC @ 3A winding is for a tube rectifier such as a 5U4GB.
However, the transformer high voltage current rating for 4 x 6L6 amp such as a Fender Twin Reverb is spec'd at 300 mA.
The 272HX is rated for 230 mA, so I'd consider it underpowered for 4 x 6L6's.
The high voltage will be lower (300-0-300) than customarily used for 6L6 amps.
The HV current is adequate for 2 x 6L6's or 2 x EL34's.