Can We Discuss Major Pigs?

[The Ballzz]

I have recently stumbled upon some discussions about Marshall Majors and a few references to the model referred to as "The Pig" and am left with some confusions. While there are schematics available for the slightly more normal, two channel versions, but only one available schematic (and redrawn for that matter) for the three knob "Pig." These amps seem quite unique in multiple aspects. From what my limited knowledge can glean, it appears that the bass and treble pots control what appears to be a separate triode each, much like it was an electronic crossover with one pot controlling the actual volume of only the bass frequencies and the other pot controlling just the treble frequencies. I could be mistaken about this, and would sincerely appreciate any info and guidance.

Also, many folks talk about these amps having a cathodyne phase inverter, but I'm not cetrtain that I'm seeing any phase inverter, especially on the Pig?

Marshall 200 a.k.a. The Pig_zpskwfv8sep.giforiginal_zpsy3zkyz1x copy.jpg

1967u copy.jpg

Thanks Folks,
Gene

[sluckey]

Major phase inverters...

[pdf64]

The Sound City 50Plus MkIV took that tone control idea a step further, adding a mid control.
I don’t regard them as being active tone controls, but I’ve been overruled on the matter by the super brains on MEF
http://soundcitysite.com/Sound_City_LB_ ... ematic.pdf

[Stevem]

I have never liked the feel of amps like these with this method of tone shaping.
I would sooner run a SS based graphic EQ stomp box in front of the amp, or in a effects loop if I felt I needed such!

I do however like the very stiff power supply of the Pig for Bass guitar!

[Reeltarded]

Majors make decibels and Pigs get slaughtered. There is a reason that design was abandoned in a burning pile.

I have a Major for sale that I haven't listed. It needs the caps reformed and a set of output tubes. Early placard 6550 model. (export) It looks like NASA laced it. Half the weight of the amp are tricks to keep it from essploding. They only sound like Marahalls because there is a logo.

[Reeltarded]

Gut shawts

36D4D34D-BF81-4F45-892C-D2E6C30E0CA3.jpeg

DDC1AE96-51D7-40B7-934B-1A0384BAA672.jpeg

9EE7E846-4226-48C2-9A55-F89ECE2B0610.jpeg

The bias board is as big as a small tweed amp lol

[Roe]

Mick ronson used a pig with bowie. the sound is rather unique, for better or worse.

majors were used by blackmore and John Frusciante and to a lesser extent SRV.

[Stevem]

In regards to the NASA mention, you mean built by the lowest bidder? Lol!

I do love these round screen resistors that they used in these amps!

[Dr Tony Balls]

I built a shrunken version of one years ago as I was more interested in the preamp sounds than the power. 2xKT66 instead of 4xKT88 and called it the Piglet.

[The Ballzz]

I built a shrunken version of one years ago as I was more interested in the preamp sounds than the power. 2xKT66 instead of 4xKT88 and called it the Piglet.

Very Cool! Please share more info. How many watts-ish? How did it sound? Willingness to share a schematic? I'm especially curious as to the voltages at the PI and preamp nodes?

This was exactly the kind of reply I was hoping to elicit from this fabulous brain trust!

Enquiring Minds & All That,
Gene

[Reeltarded]

Mick ronson used a pig with bowie. the sound is rather unique, for better or worse.

majors were used by blackmore and John Frusciante and to a lesser extent SRV.

Mick Ronson's sound reminds me of a cranked Silverface Twin with the tone controls set pretty low.

Blackmore is my reason for having these things. Joe Perry mixed one with two other amps for a couple tours in the 2000s.

What happened to that one I sold your friend?

[Reeltarded]

In regards to the NASA mention, you mean built by the lowest bidder? Lol!

I do love these round screen resistors that they used in these amps!

The insulation is ridiculous.

Those pier resistors are awesome!

Genalex designed these things. I wonder if any hi-fi guys want to blow up their 35w $80,000.00 monitors.. hmm

[Dr Tony Balls]

I built a shrunken version of one years ago as I was more interested in the preamp sounds than the power. 2xKT66 instead of 4xKT88 and called it the Piglet.

Very Cool! Please share more info. How many watts-ish? How did it sound? Willingness to share a schematic? I'm especially curious as to the voltages at the PI and preamp nodes?

This was exactly the kind of reply I was hoping to elicit from this fabulous brain trust!

Enquiring Minds & All That,
Gene

Watts-ish: 45-50
Sound: great...a bit limited but a novel and interesting concept where you basically have one really bright preamp and one really dark one and you blend em.
Schematic: below. its quite similar to the 'vintagekiki' one posted in the OP. I did a lot of research and comparison with photos and the rare Pig PA schematic floating around.
Voltages: dont have them but I wasnt trying to match anything specific. I used pretty standard 50W Marshall iron so the plates were ~450VDC

[Reeltarded]

The Pig had tremendous voltage. Over 700 and the poor screens melted.

Majors don't have a lot less. UL supply is end of the line. Melted screens ahead. Modern tubes need not apply. (that is why about one of ten still operates with original transformers) The 6550 exports are still extant in much larger numbers.

Screens at 650?

Dawk said the flyback potential is about what it takes to create life from stitched together convicts. Have you ever seen one of his rebuilt transformers? Not cheap. He was a nut.

[martin manning]

The 200W Pig schematic at the top of this thread shows 750V on the plates and 550V on the screens, and it is conventional p-p (not UL). If the OT primary impedance is made high enough to keep the plates from over dissipating, then the screens will be at great risk. Looks like a very bad idea to me. I'd cut the screen voltage in half.

For UL, a look at the KT88 data sheet says 560V on the plates with 40% screen taps and 4k5 Zaa for two tubes and 100W output. If the anode voltage is increased, Zaa has to go up to keep the plate dissipation down, and the DL fraction has to go up to keep the screens out of trouble.