Late 67 JTM45/100 EL34.

[Homebelly]

Just came by to get my daily fill of Dumble love and see that some one has added a corner for us marshall lovers.

Very cool.

I've built a couple of these now, a JTM45 and i've had my hands inside a 1987RI to do a board change.

Right now i am gathering parts for what is sometimes called a Version 5a.
This was the last of the aluminium chassis super leads before the steel chassis JTM100 "Black flags"

I've posted parts porn, i also have a layout of how to connect the dual rectifiers if any one might find that interesting..

Chassis and front pannel made by Steve Mac over on the metro forum.
Iron is Mastran.
I'm using mostly NOS parts where possible.

At this point the boards are mocked up and i haven't started soldering them yet, so everything looks a little rough.

Cheers for looking.

[img:500:375]http://farm9.staticflickr.com/8352/8356378791_0e1172726d.jpg[/img]
DSC01364 by Homebelly, on Flickr

[img:500:375]http://farm9.staticflickr.com/8214/8334879485_2382e869ec.jpg[/img]
DSC03150 by Homebelly, on Flickr

[img:500:375]http://farm9.staticflickr.com/8497/8334875567_d23827d49e.jpg[/img]
DSC03151 by Homebelly, on Flickr

[img:500:375]http://farm9.staticflickr.com/8360/8335561466_d20eee1bea.jpg[/img]
DSC03149 by Homebelly, on Flickr

[img:500:375]http://farm9.staticflickr.com/8219/8335573948_3c1fcbfa50.jpg[/img]
DSC03146 by Homebelly, on Flickr

[img:500:375]http://farm9.staticflickr.com/8492/8334512109_a0829d5431.jpg[/img]
DSC03148 by Homebelly, on Flickr

[Reeltarded]

And there we go with the most intense parts count until they made the silver amps.

Looks fantastic! Hurry up let's tube this thing and make a noise!

[Roe]

looks fantastic. be careful with grounding and forming of caps as this circuit often has problems with ghosting.

[Roe]

btw, here's my overview over the early 100w circuit: http://folk.ntnu.no/roef/JTM100.html

[Homebelly]

looks fantastic. be careful with grounding and forming of caps as this circuit often has problems with ghosting.

I'm about to start reading up on how to form the caps.
I have notes explaining a method that larry posted on the metro forum.
When i get closer to the finish, but before i wire everything up, i'll look into it to get more familiar with the method.

I'm still waiting on the back pannel.
I'm going to be adding a LAR-MAR PPIMV to this build and and i plan on keeping the two speaker outs so i will need to drill the chassis.
I don't want to do anymore until i have the pannel.

I am also starting a new job that requires me to go on a training program. I will be away for 6 weeks...

I'll update this thread as i make progress.

[Homebelly]

btw, here's my overview over the early 100w circuit: http://folk.ntnu.no/roef/JTM100.html

I actually have this and it has been very useful.
A great resource, cheers for taking the time to put it together.

[JazzGuitarGimp]

Hi Homebelly,

It sounds like you know quite a bit about the history and lineage of the Marshall lines. I have heard that Hendrix' favorite amp was a 100W using a quad of KT66's. From what I have heard, Marshall designed and marketed this amp with the KT's - in other words, it wasn't just an EL34-based amp that Jimi's tech re-tubed and re-biased. I imagine Jimi used this amp in the late 60's, which seems to be in about the same era as your build. Are you familiar with the KT amp, and if so, how close is your build to it - in both the power amp and preamp sections?

Many thanks,
Lou

[ToneMerc]

Just came by to get my daily fill of Dumble love and see that some one has added a corner for us marshall lovers.

Very cool.

I've built a couple of these now, a JTM45 and i've had my hands inside a 1987RI to do a board change.

Right now i am gathering parts for what is sometimes called a Version 5a.
This was the last of the aluminium chassis super leads before the steel chassis JTM100 "Black flags"

I've posted parts porn, i also have a layout of how to connect the dual rectifiers if any one might find that interesting..

Chassis and front pannel made by Steve Mac over on the metro forum.
Iron is Mastran.
I'm using mostly NOS parts where possible.

At this point the boards are mocked up and i haven't started soldering them yet, so everything looks a little rough.

Cheers for looking.

Very cool, the block end chassis is just icing on the cake too. Maybe one day I'll finish mine.

TM

[Reeltarded]

Try the CF master before you take a dump on your NFB with the PPIMV.

[Roe]

looks fantastic. be careful with grounding and forming of caps as this circuit often has problems with ghosting.

I'm about to start reading up on how to form the caps.
I have notes explaining a method that larry posted on the metro forum.
When i get closer to the finish, but before i wire everything up, i'll look into it to get more familiar with the method. ...
I'll update this thread as i make progress.

its best to form the caps before you solder them to the power board with the dual rectifiers. just use a 100k resistor like Larry recommends

[Structo]

Wow, cool amp.

Block ends?

This one should sound great!

[ToneMerc]

Block ends?

See the solid aluminum blocks at the chassis end for reinforcement, just as the originals.

TM

[NickC]

Block ends?

See the solid aluminum blocks at the chassis end for reinforcement, just as the originals.

TM

That's solid? Wow. At first glance I thought it was folded. Amazing!

[Homebelly]

Block ends?

See the solid aluminum blocks at the chassis end for reinforcement, just as the originals.

TM

That's solid? Wow. At first glance I thought it was folded. Amazing!

The chassis its self is folded. Then there are two solid blocks of carved aluminium at either end held in place by screws to hold it all together.

All of the early JTM45's and later JTM45/100 super amps had this style chassis. I believe the JTM45's went to folded and welded steel earlier, but that all of the amps were using a folded and welded steel chassis by early 1968.

I might have this all wrong, Roe is the guy to give a definitive answer. Personally, i'm not really that much of a cork sniffer to care.

I bought this as a "Kit" off of an other member on the metro board.
I was looking to build a KT66 JTM45/100 and some one was selling this amp as a project with about half the parts. I already had the phier's and a couple of other parts so i went for it. The idea being to try and build as close to period correct as i can. It has taken me just over a year to get to this point and i am probably about 6 months out from finishing it.