I'm having a JTM 45 clone made locally...

Falloffthebonetone

Falloffthebonetone

New member
And I'm wondering what makes them tick. I got a jtm45 transformer from mojotone and now I'm researching the amp. My local studio has one handwired by the same guy and it's one of the nicest sounding amps I've ever heard. Currently it seems Bjorn Thorsrud is borrowing it in Vegas for some stuff. I know that the original ones used 6l6gc/5881 power tubes and I THINK that is what the one at the studio was using, but then I heard that production largely switched to KT66 tubes for the JTM45s. I was wondering if there were any substantial difference between the two before the construction takes off. Thought I'd get some outside thoughts and opinions. He says it'll take a few weeks.
 
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Re: I'm having a JTM 45 clone made locally...

I believe TheGuyWhoInventedFire had a JTM45 built going for ultimate tone. I'd be curious what he used. (And curious to have one built for myself too if this works out for you!)
 
Re: I'm having a JTM 45 clone made locally...

PFDarkside said:
I believe TheGuyWhoInventedFire had a JTM45 built going for ultimate tone. I'd be curious what he used. (And curious to have one built for myself too if this works out for you!)
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I'll definitely let you know. Guy's name is Livari. You live near Orange County CA?
 
Re: I'm having a JTM 45 clone made locally...

I built a JTM45 about 10 years ago. It is just a great amp to play because it is very touch sensitive. They don't get down and dirty early like the 50 watt plexi. It's a fairly clean amp most of the way up. It gets more sustain and more liquid rather than real gritty and grindy. I have tried it with 6L6s and Kt-66s. The kT-66s sound bigger. They are huge sounding. Overdriven with KT-66s in, its got that early Cream type of tone going on. Actually, I like it with EL34s more, but that is a personal preference probably.

What makes em tick? A large part of it is the rectifier tube. The rectifier tube does the affect the tone and the head room of the amp. One wouldn't think it would, since its in the power supply and not the signal chain, but it does. The better sounding 45s seem to have NOS Mullards or NOS American 5AR4s in the rectifier slot. Tubes, bias setting, and especially speakers, make noticeable differences to the tone on these amps. I like it with G12M greenbacks, but it sounds good with Vintage 30s as well-just a different flavor of good. I haven't tried it with Celestion Alnicos.
 
Re: I'm having a JTM 45 clone made locally...

I have a hand-wired JTM45 boutique head. Uses KT-66. Haven't tried anything else in it. It's my #1 amp. Good for everything. Can do Fender clean and everything fully dimed really flabs out (in a good way) with afterburner jet kind of break up, with the right guitar and cabinet. My KT-66 bottles are "Golden Dragon", which if I understand correctly is from the company that is doing both the Gold Lion RI and the ValveArt KT-66s using the old Genelec tooling. All other tubes are NOS stuff; e.g. original Tung-Sol in P1, rectifier is GE/Westinghouse branded, not sure the actual maker. Have tried a JJ RI but the NOS GE sounded better. I'm very happy with this amp. I use others, but this easily could be the desert island head.

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Re: I'm having a JTM 45 clone made locally...

I only have one of the Marshall reissues but it is such a great amp. I usually have it set clean-ish and hit the front with some sort of drive. Sweet, full cleans and raunchy drive tones are the order of the day!
 
Re: I'm having a JTM 45 clone made locally...

Thanks for the replies guys, seems kt66 is where I'm leaning. I totally get what everyone is talking about: the fluid compression and overdrive, the "good way" it flabs out. It really is an articulate "goldilocks" amp. Cleans and distortion aren't harsh, easy enough to keep clean or overdrive when you need it, not earsplittingly loud to bother the neighbors or family but loud enough to play satisfyingly in a band. Clean, fat Fender style lows and highs with extra silkiness in the delivery of each note. The one in question I liked soundly more than a Mojave plexi clone and an Orange Rocker 30 that happened to be in the studio too. Thought it had to be the one.
 
Re: I'm having a JTM 45 clone made locally...

its a classic design based on the fender tweed bassman amp (very different than any bf circuit). the glorious midrange focus is much of the magic of the amp, full but not overly tight bottom and strong but warm top end button it up in beautiful fashion. simple and direct. for the right player with the right guitar, its a delight. i prefer kt66 power tubes over others but a well build jtm45 should have a power tranny that can handle el34's or 6l6gc just fine as well. for me the biggest difference between a tweed bassman and jtm45 is the speakers. a 5f6 though a pair of g12m sounds and feels similar to a early marshall, not the same but similar
 
Re: I'm having a JTM 45 clone made locally...

beaubrummels said:
I have a hand-wired JTM45 boutique head. Uses KT-66. Haven't tried anything else in it. It's my #1 amp. Good for everything. Can do Fender clean and everything fully dimed really flabs out (in a good way) with afterburner jet kind of break up, with the right guitar and cabinet. My KT-66 bottles are "Golden Dragon", which if I understand correctly is from the company that is doing both the Gold Lion RI and the ValveArt KT-66s using the old Genelec tooling. All other tubes are NOS stuff; e.g. original Tung-Sol in P1, rectifier is GE/Westinghouse branded, not sure the actual maker. Have tried a JJ RI but the NOS GE sounded better. I'm very happy with this amp. I use others, but this easily could be the desert island head.
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brian wallace is a great guy....he built my jtm 45/100

 
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