Authentic JTM 45/100 build diary. Clips added.

[VintageCharlie]

Here's a couple of pics of my final parts "inventarization" of all stuff that will go into the amp and with some alternatives for some positions (like preamp filter cap)/mods i was considering, though i now mostly lean towards an almost stock 45/100, with the exception of the Larry style star grounding. I can put up some higher resolution pics which would be a visual "parts list" for people just about to begin the parts-chase, as there is everything needed, and a bit more, in these pics - these should give a good orientation.
The resistors are at about 2% tolerance and most of them were actually spot-on - that's amazing about the Pihers... Pots are also very close to nominal spec, as are the mustards - at about 3%. The micas are accurate with a +/- 2pF range (i guess the accuracy of my meter is a lot lower than that) and that's the case with all of the RS micas - fantastic precision for 60's...
I will also determine the mustard cap orientation, just for the case it might decrease the chance of some noise.
Also both boards are finally ready.
Will sit down with the tech who will put this together at the end of the week and talk everything through. So i hope it might be ready by next week or maybe mid august at the latest.

[Xplorer]

Fantastic ! how much for the Karlis amplification kit ?

[Xplorer]

i was looking for four RS 1k 5w wirewound resistors, but i can't find any. do you have some left ? or someone ?
there was a store where they had such resistors, for 17 pence only each ! but not anymore, too bad.

what tubes will you use ?
what critical choices will you do with the values for this build ?

[Xplorer]

btw, you might like these :

http://cgi.ebay.com/Marshall-JTM45-Red- ... 43a8b6633b" onclick="window.open(this.href);return false;

[VintageCharlie]

Yes, i have seen these - you can get them from turretboards.com, i think and from many other places - they are the same type George used to sell in amber, just with the red plastic dome. instead. I think i will stick with a square one for the build.
No, sorry, no RS white dog bone wire wounds to spare. I had some 1k 5w's with the later square logo, but i traded and sold them. I might put in some others first though, as the screen grids pop quite easily if something goes wrong, afaik - i wouldn't be great to fry one of these right away...
Sorry, also, no source for them - i got them with 2 lucky finds to make up a complete nos quad - these ones are a REALLY tough find, especially the 1k, and even more so with the arced RS logo (500r, 470r seems to be aeasier to find). From the new ones i like the Dale wire wounds, the blac ones, as in the pic - i'd put these in if i went with modern ones - they have fantastic specs too.

[VintageCharlie]

As for tubes - TAD KT66, which are the same as Valve Art, just selected for higher standards, afaik. Reissue Mullard 12ax7 for preamp. I can go with NOS tubes later, if i happen to become rich and/or feel like there is something missing tone-wise.

For specs - stock 45/100 specs, 56k, 250pF tone-stack. A 100pF bright cap (or maybe none). 27k negative feedback resistor with 16ohm tap (also the stock setup afaik). 490v tap on the PT (supposedly 560v might fry modern tubes pretty much instantly). I think that covers the main stuff. I decided to go with stock specs and to change them later on if i feel the need.

As for the price of the "kit" - you'd have to come here and beat me to get it, but i won't give up easily!!

[Xplorer]

someone said recently that the gold lions can handle 560 v i think, in a discussion about the vintage modern amp. but i don't know how good they're, compared to the gec kt66.
i think i'll go NOS for the preamp tubes, and moderns for the power tubes.
you must be happy to endly satisfy your dream ! after all this time and efforts !

i don't understand why modern builders can't simply open an old gec kt66, analyse it, and simply replicating it ! using the same metal compositions, etc ... why producing supposedly kt66 when it's never the real deal ? same story with the univibes and effects, always some reissue, with some craps that supposedly improve the device, but in the end it's nothing as good as he original ... i'd like them to do the same, it's not like if these tubes would recquire old components that don't exist anymore ...
if they can build tubes, they can build kt66 !!! why not ??

[S.Marshall]

Where did you get the headbox Karlis? Nice parts selection.

[VintageCharlie]

The headbox is from way back when George was still selling these - it's the mojo 45/100 with the flat lip. I'm really mad at myself that i didn't get the stuff for a 12 000 series, when George was still selling the chassis and head cabs. BUT i have found a guy in UK who seems to build really great head-cabs. If you're in US, then Swanson is probably the best bet for an authentic cab right now.
Someone said that Mojo can still make the type of cabs they did for George - with flat lip, etc. (maybe even the narrow vent and/or the vox vents?).

[S.Marshall]

I wish I would have grabbed one when George had them. I have talked to Mojo and they said they could make one.

I'm planning a run of 12000 series chassis. I started a thread asking what people want me to do first. So far it's been all 69's which surprised me. Toss in your vote if you need a sweet 12 series.

http://forum.metroamp.com/viewtopic.php?f=7&t=36409" onclick="window.open(this.href);return false;

[Xplorer]

please karlis, who's this guy in england, who's building accurate jtm45/100 head cabs ?

[Roe]

I need 4 headcabs myself for 66-68 amps

[VintageCharlie]

hey guys, i will dig through my mails and find his address and let you know.

[VintageCharlie]

Sorry for keeping you waiting on the info about the head cabs! The man's name is Steve and his eBay account name is: sm10joyce. He's in UK, so this would be most interesting to guys from EU.
I asked him and he said it would be ok with him that i give his info.
I haven't bought a head cab from him yet, but i plan to do so. He was very helpful and informative and sent me pics of his work, which looks top notch and authentic too, if that's what you're after. He can also use the original Marshall tolex that is not the overly black mojo-stuff. (He said he lives 10 miles from the Marshall factory )
Give him your specs, as he told me that Marshall had several suppliers for the head-cabs and they varied quite a bit in various eras, even in the same production years.

Hope this helps.

[Xplorer]

very cool, thank you !
hope your build is going well.