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Hoffman Amps Forum image Author Topic: Marshall Major phase inverter  (Read 3859 times)

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Offline navdave

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Marshall Major phase inverter
« on: July 13, 2010, 10:58:30 pm »
Does the 1M resistor after the tone stack connect between the 100k and 2.7k junction of the cathodyne PI then to the .047uf cap feeding the buffer or directly to the .047uf cap?

Offline PRR

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Re: Marshall Major phase inverter
« Reply #1 on: July 14, 2010, 12:44:26 am »
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Offline PRR

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Re: Marshall Major phase inverter
« Reply #2 on: July 14, 2010, 12:48:49 am »
> ....or directly to the .047uf cap?

Then there would be no DC path for the cathodyne grid leakage. And hardly any drive for the lower side of the short-tail pair.

Yes, it does appear to be mis-drawn.

Offline navdave

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Re: Marshall Major phase inverter
« Reply #3 on: July 14, 2010, 01:10:14 am »
That's what I thought it was a normal cathodyne setup followed with the buffer/drive stage.
Thanks for the clarification PRR.


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Offline Ritchie200

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Re: Marshall Major phase inverter
« Reply #4 on: July 15, 2010, 04:22:29 am »
Navdave,

There are several mistakes on the power supply on that schemo too.  I would also make some suggestions on screen resistors and other items for long(er) life.  This amp morphed several times before its production ended with many things not referenced on any schematics.  Are you researching for giggles or building a clone?

Jim
« Last Edit: July 15, 2010, 04:29:03 am by Ritchie200 »

My religion? I'm a Cathode Follower!
Can we have everything louder than everything else?

 


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