Author Topic: Any JTM45 users round here? (Read 29472 times)

Twinfan · « **Reply #45 on:** September 17, 2007, 06:28:53 PM »

OK, here's the full "money shot" for HTH and anyone else who's interested:

By the way, an MI Audio Crunch Box with this amp SCREAMS :twisted:

horsehead · « **Reply #46 on:** September 17, 2007, 06:49:30 PM »

twin which package did you get please

Twinfan · « **Reply #47 on:** September 17, 2007, 07:46:58 PM »

It's a Marshall JTM-45 clone, built to Martin's specs. It's based on a Ceriatone kit with a couple of minor changes that Martin prefers to have. Nothing drastic as far as I can gather, and nothing that would alter the tone to any noticeable degree. It has Ceriatone transformers, JJ ECC83s and GZ34 valves, plus Shuguang KT-66s.

The cabinet was built by Martin and covered in my choice of regular black tolex, metal corners, stainless steel mesh over the venting holes and a silver handle. I also requested the white panels and the chiecken head knobs. Everything is customisable for a price.

He basically builds you what you want, although he's going to be introducing some standard models in the near future based on the 18w Marshall design.

38thBeatle · « **Reply #48 on:** September 17, 2007, 08:29:07 PM »

That does look terrific and I have been reading the thread and it sounds as if you are pretty pleased with it-great choice.

Will · « **Reply #49 on:** September 17, 2007, 08:45:20 PM »

you big meany!

I want one of ceriatone's line!
a decent enough bank balance doesn't help, but I think a feline guitar shall be first :lol:

HTH AMPS · « **Reply #50 on:** September 17, 2007, 10:58:40 PM »

Smart guy, he's only used carbon comp resistors on V1 and V3 plates (i.e. where there is a large voltage across them). This is where you get the 'magic' that people associate with CC resistors.

I would have also used them for the plate load on V2a (the 100k on the valve base) and also for 100k cathode resistor on V2b but that's just my preference.

I remember tweaking my AC20 and I really couldn't believe how much the amp opened up when I used CC resistors in place of the CF ones I'd previously used.

Overall I'd say it's a nice neat build. I always use multiple star grounding over the bus-bar that he's used (and Marshall always used in plexis), but again that's just a personal thing. I'm just used to keeping grounds together for each node on the HT rail from when I've built high-gain valve amps where it's more critical.

I don't think you can grumble at all with that amp - it's built equal to the Marshall HW series amps I've seen and better than many vintage valve amps I've serviced (Sound City and Simms Watts spring to mind).

:twisted:

Twinfan · « **Reply #51 on:** September 17, 2007, 11:04:17 PM »

Cheers HTH. As you say, he's used carbon comps in the key places for tone and not elsewhere (to keep background noise down). As you say, lots of things are personal preference and he has done his take on the JTM-45 circuit. It sounds good to me.

Can't wait to crank it at my next gig through my V30/G12H 4x12 :twisted:

fps_dean · « **Reply #52 on:** September 18, 2007, 12:47:23 AM »

I rock a 1969 Marshall Major.

I will be rocking a Roccaforte DRRS or possibly a Splawn quickrod sooner or later....

Anything that's like an older Marshall, including older Marshalls gets a thumbs up in my book!

horsehead · « **Reply #53 on:** September 18, 2007, 07:46:58 PM »

Twin, your a scoundrel & a git...I ended up speaking to Martin today

I hope you know that a wife maybe after you & not in a good way

Twinfan · « **Reply #54 on:** September 18, 2007, 10:36:59 PM »

Ha ha :lol:

WHat have you ordered/asked about???

Brow · « **Reply #55 on:** September 18, 2007, 11:11:56 PM »

Did you order this amp in a kit from the USA and he built it for you and boxed it up etc? Or did he build it from scratch?

I ask because I don't see a JTM45 style amp on his website apart from yours :D

Twinfan · « **Reply #56 on:** September 18, 2007, 11:21:20 PM »

He'd actually ordered some bits of the JTM-45 kit from Ceriatone in Malaysia (basically the chassis, transformers and circuit board), with a few component tweaks that he wanted. The rest of the amp parts he either had in stock or sourced locally (other caps, valve bases, fuse holders etc) . He wanted to try building a JTM-45 for his own experience (there was no order for one) and this amp was his first attempt.

When I first met him he'd built the amp with 6L6s, gold panels, standard Marshall knobs and no cabinet. He'd used it in rehearsal and decided it wasn't really his thing and he preferred his 36w. I tried it, liked it, asked him to switch it to KT66s, white panels, chicken head knobs and to build a simple cab for it to my spec.

He now really likes the amp and may build himself another. And I got the great sounding prototype :D

horsehead · « **Reply #57 on:** September 19, 2007, 06:18:48 AM »

Basically the exact same as yours mate with some cosmetic changes, he was knowledgable, funny & really helped me understand which is the best way to go with the amps i.e. I flirted with the idea of 36w but came back to the JTM45

she's gonna kill me!

Twinfan · « **Reply #58 on:** September 19, 2007, 09:33:07 AM »

Nice one matey. Sounds good!

The 36w is a great lower powered Plexi, but they just don't do cleans or light crunch. It's gain all the way. Great in a rock band, not quite so good if you want a bit more flexibility.

I just dying to crank my '45 up!

horsehead · « **Reply #59 on:** September 19, 2007, 10:11:39 AM »

so are we! :P