Building Marshall Slash Head, but 50w el34, curren

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slash
Junior tube assistant
Posts: 1
(1/31/04 11:07 pm)
  Building Marshall Slash Head, but 50w el34, current rating?
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Hi chaps, great forum

I have been searching around for specs on usinf el34s

I have a 350 - 0 - 350 power transformer rated at 160ma, with 4.5A on heaters

Will this power 2 x el34 at 50w? Will it go into meltdown? I noticed the hoffman marshall 50w replacement power tranny is only 150ma, but the 50w hoffman power trany is rated at 250?
I basically need to know if this power tranny will be ok even if im running at full power?

My output tranny is rated at 50w @ 3400

My choke is 15h @ 100ma is this ok for 50 watt el34 amp?

I am trying to copy the slash amp but at 50w, i have the marshall 2555 schematic which i think is the same as the slash model and i will be changing to run with 2 x el34s, any thoughts on this.

Im not sure what i can do about the bias supply as there is no tap for this, though on the power tranny there is a 5v tap which will not be used?

I have been reading that at lower voltages the el34s will use more current, so will this tranny after converting to dc run at the right sort of voltage.

Thanx in advance

Ps. Please post any links to similar projects, 50 marshall, slash marshall pages etc


 
pzung
Junior tube assistant
Posts: 4
(2/1/04 2:55 pm)
  Re: Building Marshall Slash Head, but 50w el34, current rati
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 you can make a freestanding power supply for the bias with a small 25volt 450ma transformer wired as a voltage doubler with the parts in reverse for negative output .
from ground run one IN4007 diode to one output from the transformer .
from same ground run one 100mfd-35V capacitor to the other output .
from the output with the diode run another diode to the bias . from the output with the capacitor run another capacitor to the bias .
the end of that second capacitor and the end of the second diode meet at the bias . all the plus signs point towards the transformer . this should give you -70volts . oh yeah wire the primaries to the same places that the primaries of the power transformer connect ... on off switch and fuse .
 
 
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