Jtm 45 Gathering

Niilopi

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Hellö,

I sold my vintage -76 JMP 100W 2203 cause it was modded and kind of raped in a way that it wouldnt have any value left. Ive been looking at JTM´s anyway for some time because JMP was always too rocknroll for me as im more of a bluesy player.

I started lookin around and doing research. JTM reissue was about the only option for me for 1300-1500euro pricerange and any good boutiques werent available anywhere used atm. So i found this cool handbuilt chassis on ebay. This seller has more stuff for sale so check out : http://www.ebay.co.uk/usr/retrotronicst

Its made with NOS components as close as possible to the original JTM:

2mm aluminium chassis
3mm paxoline board with NOS vintage split top turrets
NOS original Phillips Mullard Mustard capacitors
NOS Morganite/Piher/Beyschlag resistors
F & T filter capacitors
Cliff jacks vintage style
British made Castelco power and stby switches
Magnetics components choke
Belton Micalex tube
Littelfuse US fuse holders
Alpha pots, set-screw knobs

Its missing the OT, PT, Tubes and a box.

Transformers:

So i did my research and ended up looking at Metro/Marstan/Merren/Classic Tone for the right transformers to make this baby sing. At the end it really came down to the price and tone. Ive heard a lot of good from all of these manufacturers and the prices vary very much from 140dollars to 365dollars for OT+PT. The cheapest one Classic Tone and most expensive Merren. I tried contacting Marstan for an order but they didnt answer me so i turned to Classic Tones which is a bargain of a price also! I got Classic Tones shipped to europe for 230 dollars/ 200euro. One huge aspect on choosing classic tones was availability! They were ready to ship once the other ones would take 2-3weeks to manufacture.

Box:

For boxes in europe i found two pretty cheap solutions. Mostly they will cost you around 350euro + shipping for a good box. However i found a few pretty good choises:

-Modulus Amplifications in UK makes JTM boxes for 165pounds + shipping, +20bucks for custom colour tolex
-Tube-town.net sells a JTM box for 230euro + shipping

Tubes:

Im still looking for the right tubes to get the sounds to the top. KT66 will be my valve choise.

Price:

The prices for re-issues used are around 1000euro. The new one from thomann costs 1400-1500euro. Good boutiques can be found for 1500euro used but are not often available as in my case.

My project costs: includes shipping:
By far:
730e The chassis with all components except OT, PT and tubes.
200e Classic Tone OT and PT
Expecting:
210e Box
150e Tubes

So im looking at 1290euro for a full spec JTM 45 with close as possible original spec components! I think thats a good choise for a re-issue even if it doesnt carry the real Marshall name and resale value. Im looking for a players amp.

Let me know what u think and im looking for suggestions for choosing the right tubes.
 
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Niilopi

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Heres some pics of my JTM 45 chassis
 

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neikeel

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Looks excellent, be interested to see what you think of the transformers, do you know what/how an original vintage JTM45 plays with NOS Mullards and GEC KT66s?
 

Niilopi

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No i gotta say i dont have much experience on different tubes. Ive been looking at valve art kt66. It could be a possibility to order atleast one NOS mullard for v1 as thats the most essential stage for sound right? How would one identify the right nos tube from ebay europe? Is it the yellow label ones that are killer?


Looks excellent, be interested to see what you think of the transformers, do you know what/how an original vintage JTM45 plays with NOS Mullards and GEC KT66s?
 

neikeel

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The VA and Gold Lion KT66s actually sound pretty good. The only question mark is over their longevity. It will be worth buying ones with a guarantee (pre burned in etc). As far as preamp valves are concerned I suggest you get the amp running with some new ones and then take a look at ebay for sellers who give test data (so familiarise yourself with new test numbers) and who will take back if faulty (only real way to test for noise/microphonics is in the amp) or buy a few cheaply and sort them yourself. BVA Brimars, Mullards and Mazda are all ones to look out for, you will also find Tungsram, Telefunken and old Tesla at good prices if you pick and choose.
 

ampmadscientist

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Well, 66 is a good tube- it costs 2X as much as EL34.
And the bias must be changed to run 66.

That's probably why you don't see more amps w/ 66....
even though has a better blues / R&B tone.

Cheaper choice is just run 6L6 / 5881 and change bias.
 

Niilopi

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Getting an idea about the tubes trying to use my local tube shop:

Kt66
Valve art

Gz34
TAD 5AR4 premium selected (mullard replica)

Ecc83
V1 & v2
7025 S TAD premium selected Mullard style. For v1 5751 or 12ax7.
V3 ?? 12ax7 vs 12at7
 
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ampmadscientist

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Getting an idea about the tubes trying to use my local tube shop:

Kt66
Valve art

Gz34
TAD 5AR4 premium selected (mullard replica)

Ecc83
V1 & v2
7025 S TAD premium selected Mullard style. For v1 5751 or 12ax7.
V3 ?? 12ax7 vs 12at7

If you put a different rectifier tube in, this will change the B+ voltage and the amp needs to be re-biased.

5Y3, GZ34 5AR4/ 5U4 will all work, but will change the B+ over (about) a 90V range, at 100ma current draw.
 

Niilopi

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the amp hasnt had any tubes in yet so ill have to bias the whole thing anyway
 

SmokestackElRopo

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Good luck in your quest! I use Valve Art KT66 and NOS preamps from Martystrat54 in my RI JTM45. I have not failed a tube yet, and get what to me is great tone. Pair it up with some Eminenece or Celestion AlNiCo speakers and it should break the world. My personal recommendations only. I did have to rebias the amp when I switched to ktz from the 5881z. If you're a gambler with lottsa money go for nos GEC KTz.
 

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