Wednesday, 1 May 2013

The kit

This is the post I saw which sold the idea to me!

Kit 1 will be the most spectacular and most complete kit. It's for a replica of the extremely rare 2×12" 18 Watt JMP Lead & Bass combo, type no. 1973.

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The perf boards are fabricated by none other than Ray Domzalski in the USA, made fibreglass that won't absorb moisture and become conductive like the original brown "Tufnol" boards (phenolic paper) that will cause all sorts of noise and reliability issues. Ray uses really nice looking authentic '60s style tinned brass turrets with the two stories and the slotted tops.
I'll include the screws, nuts, lock washers and standoffs that I mounted before making the shots below.

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I only have enough knobs left for one kit. These are original Marshall knobs, not the rubbish that some will say "looks close enough." All the carbon film resistors are there, as are the electrolytic, ceramic and silver mica caps, but I only have three of the four required .01µF Mustard caps. I put two .0082µF and one .012µF Mustards in the ziploc baggy. It's up to you if you want to be a little creative with the values or go and look for the last .01µF cap elsewhere.

I have no power resistors left in my attic, you'll have to get one of each of the following: 100r/3W, 125r/5W, 1.5k/2W, 2.2k/2W, 8.2k/2W.

Enough EZ81 rectifiers and pairs of EL84 power tubes, but you're going to have to get the three 12AX7 preamp tubes yourself.

Plenty of shielded cable. I will snip up the roll I photographed put more than enough length in each kit. Nearly all the regular wire is gone though, you're going to have to order some yourself.

If you want to do it right and put that little wedge of cheese on the floor, finished in hammered paint, Marshall has a nice looking vintage foot switch for you: PEDL-10034

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The transformers are from S2. His first, last and only European order. The output transformers are absolutely the best sounding ones I have ever had in my shop.

The Power Transformers are made for the 220–240V 50Hz area come with two things that are important to me, but most tend to cut costs on these details. First, a frame for added rigidity. You want that when using an aluminium chassis. The big washers that most builders use (and even boutiques, mind you) don't do it for me and don't look like a professional job to me. The other thing is an end bell *snicker* to protect the core, reduce electrostatic radiation en provide electrostatic shielding.

The output transformers are the best there ever were, period. I worked with Heyboer and Hammond before, had a Mercury Magnetics restore a blown Tweed Deluxe OT kicking around the shop for a while and had plans to let a company on this side of the pond create one based on this, but then these came along. To my ears, most transformers used for 18 Watters pass too much highs, causing a very nasty and fizzy sound. The irons that you'll get with this kit tame these nasty highs while still keeping the musical highs, giving you all the tone and charm that makes these amps so beloved.

But there's a whole lot more to these irons than just the shaped highs, here's an old review on the Trinity Amps forum from when S2 was still in business:
s2 Output Transformer in my Trinity 18
4, 8 and 16 Ohm secondaries so you can connect everything to it that you want.

I don't have screws, nuts and lock washers for the OT, and the PT comes without lock washers.

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Here are some snapshots of the chassis, I mounted all the pots, jacks, switches, tube sockets and everything else just to see what I still have and what I don't. Everything turned out to be there ! Even the screws and rings to mount the top back panel of the cab to the chassis.

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The cab I had intended for this amp is an absolute marble, made like a mid '60s 2×12" combo with vintage Marshall style black-on-green levant tolex, Bluesbreaker grillcloth and VOX-style vents. This will really set your amp apart from the rest ! This cab is brand new. It arrived, I unpacked it to check it, installed the speakers to save space and put it in the attic. Only to unpack it a week ago for fresh photographs.
All speakers in the combos are proper English made Celestion G12H Greenbacks. They are from the Heritage Series and sport the heavy magnets, by far the best sounding speaker for these type of amps. To me, the G12M with the lighter magnet is too weak to be in an open cab (especially when it's a 1×12" cab) they just don't build up the pressure. The G12H speakers I used for these amps sound absolutely brilliant !

You have to drill the holes for mounting the chassis to the cab and get the screws to do this, drill the holes for back panel to the chassis and get a bit of wire and a plug to connect the speakers to the amp. I can send you a PDF with a drill-template for the current production 6" Marshall logo or you could get a block-logo reissue on eBay if you like.

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