# MARSHALL MAJOR 100 watt amp build



## collector (Feb 12, 2017)

hello again , being a huge marshall fan and a lover of the kt-88 tube , I was wondering if anyone has anyone had the quest to build a 100watt version of the 200w major . I am in the process of aquiring parts to buuld this beast with merron custom wound trannys , tesla kt88 tubes , all iska resistors and mustard caps , F&T filtering . nos pre tubes , housed in a jcm 800 chassis going to be 600 volts plus plate voltage , looking for a real schematic for the build , as there are many online that are wrong , im looking for the accurate one


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## bolero (Oct 11, 2006)

sounds like a cool project!!

Merren transformers too...wow. I'm sure it will sound amazing


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## Louis (Apr 26, 2008)

Wanted to build a mini Major a few years ago
a friend of mine has one , two KT88's is aroind
70 watts with ultra linear transformer,
think I still have his gut pictures but not sure.

He nails Blackmore like you wouldn't believe!

His name is Max and here he is playing,


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## sambonee (Dec 20, 2007)

Sweet playing. He needs to try a v- Pick (doesn't everyone). Pardon the shameless plug.


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## collector (Feb 12, 2017)

these are the newly made merren audio transformers for my mini major build c/w new kt88's and a custom badge made . the build is going to be done by steve moratto of moratto amps in ajax ontario , killer marshall plexi builder .


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## Granny Gremlin (Jun 3, 2016)

collector said:


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> these are the newly made merren audio transformers for my mini major build c/w new kt88's and a custom badge made . the build is going to be done by steve moratto of moratto amps in ajax ontario , killer marshall plexi builder .


I use a quad of those same NOS military grade ( thicker glass) Teslslovak KT-88s in my Sunn 1200s. They're pretty tasty. Very beefy; more so than the stock GE 6550s that were in there when I got it. A bit looser vs controlled but not to a bad degree, just in terms of comparison.

Cool project; will be watching.



Louis said:


> two KT88's is aroind
> 70 watts with ultra linear transformer.


The spec sheet for the KT-88 says Pout can be 100 watts in fixed bias ultralinear mode (50 in cathode bias) - see pg 4 here: http://www.r-type.org/pdfs/kt88.pdf. Sunn called it 60 ( but that was because the spec for the 2x15 JBLs was 25 To 30 each and they didn't want people to think the speaker was under- rated).

From my experience with a quad in my Sunn ( also ultralinear) it is definitely closer to 200 vs the 120 rating, based off running other amps into the same cab.


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## collector (Feb 12, 2017)

i

im only running 2 kt88's ultra linear 650 volts on the plates possibly a little more , not shure what steve will build ,and how he will set it up to run at high voltage ,but I want it as high as possible to get that major tone .


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## Granny Gremlin (Jun 3, 2016)

collector said:


> im only running 2 kt88's ultra linear 650 volts on the plates possibly a little more , not shure what steve will build ,and how he will set it up to run at high voltage ,but I want it as high as possible to get that major tone .


According to that spec sheet above, 100 watts can be had from a pair with 560V on the plates, so 650 should easily get you there. Note; higher plate voltage <> better tone. My Sunn runs em at 500V according to the schem (but likely higher IRL). The max rating is 800, so it's safe.


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## collector (Feb 12, 2017)




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## JC103 (Oct 6, 2007)

Where did you source the transformers? They look like Heyboers!


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## collector (Feb 12, 2017)

JC103 said:


> Where did you source the transformers? They look like Heyboers!




chriss merren of merren audio wound me a both trannys for the major build , his pwr tranny has taps for 460/560 volts , so im trying out another tranny from hammond 1st that supposed to have 600 v plus , I have to measure it once its going


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