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AmpKiller66 24th April 2009 04:19 AM

Marshall 18W clone (sort of)
Hello, I have the power and output transformers from an old organ that used 4 EL84s in the power section, along with numerous 12AX7s. I was wondering if it would be possible to make a clone of a Marshall 18W with these transformers, except with 4 EL84s instead of 2 in order to compensate for the impedance mismatch (and to bump up the output power). The voltages from the power transformer are roughly what you'd get from a Marshalll power transformer, but would the existing preamp circuitry and phase inverter be able to drive the additional EL84 per side?

AmpKiller66 24th April 2009 04:27 AM

Here's a link to the schematic: Marshall 18W

leadbelly 24th April 2009 04:27 AM

Build this:

AmpKiller66 24th April 2009 04:30 AM

Thanks! I'll look into it, and I'll probably try both, but for the sake of the original question, could you drive 4 EL84s with the preamp of a Marshall 18W?

leadbelly 24th April 2009 04:35 AM

The circuit I linked is essentially the 18W circuit with 4 EL84's:

AmpKiller66 24th April 2009 04:38 AM

That it is:) It's been a long day...

mashaffer 24th April 2009 11:28 PM has an entire section on 36watters. Very helpful guys there that were in invaluable in helping me build an 18watt variation for my grandson.

AmpKiller66 25th April 2009 01:01 AM

I just registered at thanks for the advice.

mashaffer 25th April 2009 01:44 AM

No charge. ;)

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