New project - Metro JTM45 combo or head?

[johan]

Hi (from Sweden)

I’m a beginner when it comes to building amps. I’ve built many pedals, my soldering skills are good and I can get help from a friend in case something happens.

I’m collecting parts to build a JTM45 / Bluesbreaker amp. I have trannies and choke coming from Marstran this week. I will get most of my other parts from Metro. Maybe the Sozo vintage premium caps from the Sozo-site.

This will be a project that will go on for quite some time as I’m kind of busy at the moment (moving to a house this fall + baby girl). I will take this slow and do it the right way. I will update this thread if I have some questions and not litter this forum with new threads every other day.

I will try to get all the parts before I start building. I will use the Metro JTM45 guide.

What I have – Marstran RS OT, Marstran 1202-55 and Marstran RS 20H Choke. I will probably need some help, or verification that I get the wiring correct before I fire it up.

My first question is regarding the parts and construction – Is it possible to do this as a Bluesbreaker 2x12 combo using the transformers above and the Metro chassi? I’m thinking of the transformer placement, horizontal/vertical, space for tubes and speakers and such. Have anyone done this? Anything in particular to think about before I get all the parts?

I’m more of a combo guy. Don’t ask me why

Since I’m in Sweden I will get the cab in Europe to save some $$$. How about a Mojo 2x12 Bluesbreaker cab. Will that do?

Speakers – I know the Scumnicos are great speakers! I used a pair for a 18W 2061 amp. Unfortunately I sold them…They cost a fortune but hopefully I can get them again. If not, how about Celestion Blues/Golds or Weber Silver Bells? I want Alnico speakers.

That’s it for now.

Cheers

johan

[bristol]

I built a stock Metro JTM 45 with the typical upgrades - sozo, CC resistors, PEC pots, Mullard preamp glass, and some electrolytic cap upgrades. I mounted it with no problem into a Mojo bluesbreaker cabinet. You will need a piece of sheet metal to shield the bottom of the chassis since the Mojo BB cabinet does not have one. George included one in my kit. The only thing to watch out for is that the Mojo cab is not exactly like a real BB in that with the Mojo, you have to mount the chassis to the upper rear panel. I think in a real BB, there is a frame which holds the chassis in the cabinet so that you can pull off the upper rear cabinet panel without taking the chassis with it, which would be much more convenient for things like biasing. I guess you can mod the Mojo cab to hold the chassis without the rear panel if you want to.

I am not sure if your iron will fit in George's JTM 45 chassis, but I suspect they will.

I used a Scumnico paired with a Scumback.

Amp sounds great.