JTM45/100 dual OT kit?

HEAVIER THAN HELL · Post by **HEAVIER THAN HELL** » Sun Dec 16, 2007 4:49 pm

hi, introductions first since I'm fairly new round here. My name's Ian, 32, Marshalls have always been the last word in amps for me. Currently playing a '76 Superbass that I've modded to '67 plexi specs with a pre-PI master volume. If anyone here is on the Plexi Palace BBS, I'm called Velatones on that board, or Ian Anderson on the LPF or HTH on the BKP forum.

I'm interested in a dual OT JTM45/100 but there doesn't appear to be a kit available for one. Anyone got some specs for this?

What PT and OT will currently get me closest to that tone?

Anyone got info on how the two OTs are hooked up and if that amp can run on a single cab (i.e. does it need a seperate load for each OT).

Thanks in advance, lots of questions I know.

Billy Batz · Post by **Billy Batz** » Sun Dec 16, 2007 6:26 pm

There arent 'kits' for any of the earlier amps here but theres more then enough parts to get it done. You would start witht he bare bones kit and work from there. The only thing is right now the early aluminum chassis' arent in stock and theres no ETA for that but some of us are waiting diligently. The BB kit comes with steel chassis.

From what I know the Dual OT JTMs were paralleled so they function as one OT and you dont need 2 loads. At least some of them anyway. I think (I may be wrong) that the 2 OTs were just 2 RS tranies. I dont know of any power trany that clones the huge beasts that were in those amps but the JTM100 trany here will work.

You can email or PM member Brian Wallace of Marstran Tranys and Wallace amps. He does dual OT JTM100 clones and he may be able to help you.

wdelaney72 · Post by **wdelaney72** » Sun Dec 16, 2007 8:21 pm

I've get Brian's iron in my JTM 45/100 build. I opted for the single OT, though.

white room · Post by **white room** » Mon Dec 17, 2007 8:42 am

Ian,

Welcome aboard!

I re-built my SLP R/I to JTM100 specs using George's JTM100 OT and it really does deliver the goods.

HEAVIER THAN HELL · Post by **HEAVIER THAN HELL** » Mon Dec 17, 2007 2:36 pm

Thanks for the replies guys. I was planning on using Marstran iron anyway, so I'll pick Brian's brain while I'm at it.

Ceriatone do a JTM45/100 alu chassis (apparently) so I'll have to order from them.

The rest I'll get here since the boards look fantastic. I should be able to salvage some old pots and Mustard caps I've got here from various amps I've got over the years that were knackered and only good to strip for parts.

Billy Batz · Post by **Billy Batz** » Mon Dec 17, 2007 4:58 pm

I was thinking of getting the Ceriatone chassis but George said he hasnt forgot so Ill wait a bit longer.

NY Chief · Post by **NY Chief** » Mon Dec 17, 2007 5:19 pm

Doesn't the RI 45/100 use a separate OT for each speaker jack?

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http://reviews.harmony-central.com/revi ... +Head/10/1

The amp uses two separate 50W transformers in its output stage and so it has two sets of speaker jacks - one for each output transformer. It is not stereo, but dual mono.

Billy Batz · Post by **Billy Batz** » Mon Dec 17, 2007 5:49 pm

Yeah I knew that one did but I dont think originals did. At least some originals. I remmeber talking to BrianW about this years ago.

white room · Post by **white room** » Tue Dec 18, 2007 8:43 am

I have always wonderd how many dual OT heads Marshall made before the switch to singles.

Wasn't it just a handful of the first 100 watters that used the dual format before Marshall switched to a single OT?

HEAVIER THAN HELL · Post by **HEAVIER THAN HELL** » Tue Dec 18, 2007 12:46 pm

white room wrote:I have always wonderd how many dual OT heads Marshall made before the switch to singles.

Wasn't it just a handful of the first 100 watters that used the dual format before Marshall switched to a single OT?

As far as I've read, they were made for The Who and The Small Faces and only a handful were produced. Seems they keep cropping up now and again though, so there were probably more made than we think (or lots of lash-ups around).

From my perspective, it's a sound that I'm not going to get a chance to gig with unless I make one myself. I'm expecting it to be very much just a louder JTM45 whereas the single OT 45/100 does seem to have a slightly different tone to a JTM45.

Billy Batz · Post by **Billy Batz** » Tue Dec 18, 2007 1:30 pm

Thats what I thought too. They did a single one as a prototype. Then they did the Magic Bus amp and one or two more before they used 'production' tranys.

BTW if anyone still has the pics of the magic bus amp please PM me. Theyve been around but I never save them.

HEAVIER THAN HELL · Post by **HEAVIER THAN HELL** » Tue Dec 18, 2007 5:23 pm

Billy Batz wrote:Thats what I thought too. They did a single one as a prototype. Then they did the Magic Bus amp and one or two more before they used 'production' tranys.

BTW if anyone still has the pics of the magic bus amp please PM me. Theyve been around but I never save them.

^ +1, I'd like to see any pix of dual OT JTM45/100s for sure, but any single OT JTM45/100s will be of equal interest.