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First amp build questions
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Old 13th May 2004, 01:23 PM   #1
edsmith is offline edsmith  Australia
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Question First amp build questions

im building a slightly modded marshall 1987 plexi for my first builld. I really like plexi amps but i really like that smooth tone from old fender amps also. I noticed the Fender 'Super Amp' 5E4-A schematic is very similar to the 1987, but they have different tubes.

super amp has:

2 12AY7s

1 12AX7s

and for the power tubes

2 6V6

while the marshall has 3 12AX7s and the 2 EL34s.

super amp schem:

plexi schem:

Would I be able to take the plexi tubes out and whack in the super amps ones without something bad happening?

thanks guys,
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Old 13th May 2004, 05:31 PM   #2
Sch3mat1c is offline Sch3mat1c  United States
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Without looking at the schematics, I can tell you you'll have to rebias and rewire the sockets to use EL34s in place of 6V6s. Since you're doing a new build you could just chop the EL34 output circuit and paste it onto the driver circuit you want. Although being a guitar amp I wouldn't be suprised if you could get away with it anyway, making sure all the grids are connected that is.

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Old 13th May 2004, 08:06 PM   #3
drembo is offline drembo  United States
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Default plexi vs tweed super

The plexi with 6V6 output tubes is still going to sound pretty much like the plexi. The plexi has much more gain coming out of the preamp, the tone controls are completely different, and I think the plate voltages on the output tubes of the plexi circuit are going to exceed the maximum values for a 6V6 tube.
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