JTM45 in combo cabinet

[Joe Popp]

I am thinking about trying to fit a JTM45 in 18 watt Combo Cabinet. Is there any reason why this wouldn't work. The dimensions seem to say that it would. I am looking for a small amp and I think a JTM45 crammed in here would serve me just fine. Need something small and portable.

Here is the cabinet:
http://www.mojotone.com/amp-parts/Marsh ... bo-Cabinet

[neikeel]

It will fit ok.

I put a JTM45 head into a 2x12 18watter combo cab.

Not sure what speaker you have in mind but I would go for either a Celestion G12-65 (lead cone) a Celestion Gold or of course a Scumback 65watt. I think these combos benefit from a Weber beam blocker too to spread the sound out a little.

[vrswiss]

I am in the process of doing this now. The stock 18w 9" depth wont let you run KT66's from my calculations. If you take into consideration the depth of the back panel and recessed baffle and thickness there may not be enough room for the KT66's to clear the speaker/baffle. 5881's would probably work though. Another downside to the actual Mojo 18w cab is the back panel isn't 1/2 like the 2x12 BB cab is. Since the JTM is heavier and is going to be suppoted by the back panel the 1/2 is a must in my opinion.

I chose to have JD Newell make my cabinet because he will tweek it anyway you want to match the amp. Mine will be 10" deep instead of 9" so I can run KT66's, 1/2" back panel and 3/4" baffle. He also shifted the speaker cutout slightly lower in the baffle for me to help the tubes clear the speaker frame. I should have the cabinet in another week so I'll put up pictures of my results/fit. I kinda wish I would have had him make it a little deeper even maybe a little taller for piece of mind.

As for a speaker I have a 50w 16 0hm weber silver bell and/or bluedog to try. These two speakers sounded great in the 2x12 cab I was playing this with. Once I know which sounds better I'll probably buy another but 75w version this time around to ensure it will last. JTM45 cranked could exceed 50w I guess. The amp does have a lar/mar on it though and I usually don't get it past half volume so I would guess it the 50w speaker would be fine really.

By the way, anyone have any bluesbreaker reissue cloth to sell? Its out of stock everywhere so I am just having him put salt and pepper on it for now. Maybe if she works out and stays I''l spring for some E.C Collins pin stripe I doubt it though at $250 for a piece to fit it. Thats crazy!

[Joe Popp]

Thanks neikeel and vrswiss! Measuring my small box cabinet, there seems to be 7 3/4" of actual space so I think I may be able to fit it. vrs swiss: you do make an excellent point about the tubes clearing the speaker frame and the thin back panel. I really miss my JCM800 so I am thinking about putting that in there instead of the JTM45. The EL34s are shorter so that might help matters out.

If you guys have any pictures, that would be great.

Thanks as always metroamp brothers!

[vrswiss]

This will be the first Marshall cab I bought from JD Newell but by the computer drawings/specs he sent me it will be top notch. Plus, he was very helpful in coming up with the specs on what we should modify on the standard 18w cab to fit the big amp. I have seen a 2x10 Fender super reverb cab he made which was excellent quality workmanship and materials . $299 with a 20 day wait for the BB cab. Plus, you can get it any color or available Marshall grill combination without the upcharge like mojo hits you with. Unfortunatley there is a worldwide shortage of the reissue BB cloth right now though. Tell him I sent ya!

[Bluesbreaker]

I had this same dilemma. I will not be carting my Plexi full stack around to rehearsal, gigs, or friends houses to jam. I have a custom built Jeff Swanson, Marshall Style I 2x12 combo that houses my Metro Amp JTM45. This, too, is rather heavy and bulky for carting around.

I contacted Swanson Cabinets, again, and discussed with Jeff the building of 1x12 cab, in the Marshall Style I features. He said he will build it to perfectly house a Metro Amp JTM 45 chassis. It was under $400, your choice of tolex (I chose red), white piping and baskeweave cloth. The chassis fits it like a glove. Oh, I purchased a Scumback speaker, too. Looks great and sounds, well, like the typical fantasic Metro Amp JTM 45.

[Joe Popp]

I had this same dilemma. I will not be carting my Plexi full stack around to rehearsal, gigs, or friends houses to jam. I have a custom built Jeff Swanson, Marshall Style I 2x12 combo that houses my Metro Amp JTM45. This, too, is rather heavy and bulky for carting around.

I contacted Swanson Cabinets, again, and discussed with Jeff the building of 1x12 cab, in the Marshall Style I features. He said he will build it to perfectly house a Metro Amp JTM 45 chassis. It was under $400, your choice of tolex (I chose red), white piping and baskeweave cloth. The chassis fits it like a glove. Oh, I purchased a Scumback speaker, too. Looks great and sounds, well, like the typical fantasic Metro Amp JTM 45.

Bluesbreaker and Vrswiss: I would love to see pics of these cabinets. Also any approximate dimensions would be awesome. Thanks!

[vrswiss]

Alright, here she is. Sounds and fits great. Glad I went 10" deep instead of 9" because there is about 1" between the top of the KT66 retainers and the edge of the speaker frame. Its stock 1974x dimensions except its 10" deep and has a 1/2" back panel. This cabinet cost me $333 shipped from JD Newell. Really isn't that heavy so its gonna get used a lot more now than it was before. Still got the old 68 4x12 though If anyone orders one from JD Newell tell him Jason Butler sent ya. Maybe he will cut me a deal on my next cabinet if I sent him some work . I could use a 2x10 for my super reverb. Hahaha.

[Joe Popp]

Thanks for the detailed pics vrswiss! Much appreciated...

I contacted Jeff Swanson and he is making me a really small cabinet for my JTM45. It will be 20 x 20 x 11. I wanted it as small as I could get. It will look like a Borg Cube! I will put pictures up here.

[mwm523]

Wow vrswiss, that looks great! I've been seriously considering doing something like that for my JTM45... I haven't been using it much lately, I've been using my Allen Accomplice since it's much easier to grab and go with a 1x12 combo, and it takes up much lees room on the small stages I typically get squeezed onto. But I miss using the JTM... I'm thinking my JTM in a cab like this with a Scumnico 65W would sound heavenly...

[vrswiss]

Wow vrswiss, that looks great! I've been seriously considering doing something like that for my JTM45... I haven't been using it much lately, I've been using my Allen Accomplice since it's much easier to grab and go with a 1x12 combo, and it takes up much lees room on the small stages I typically get squeezed onto. But I miss using the JTM... I'm thinking my JTM in a cab like this with a Scumnico 65W would sound heavenly...

I've got a 65w Scumnico on the way . So far I'm digging it, plenty loud and sounds good with the ceramic blue dog. Can't wait to try the sumnico. Gonna try it out officially at rehearsal this week.

Joe, you gotta post up pictures of the cube when she's all done. Its gonna sound mean for a little amp.

[Joe Popp]

Wow vrswiss, that looks great! I've been seriously considering doing something like that for my JTM45... I haven't been using it much lately, I've been using my Allen Accomplice since it's much easier to grab and go with a 1x12 combo, and it takes up much lees room on the small stages I typically get squeezed onto. But I miss using the JTM... I'm thinking my JTM in a cab like this with a Scumnico 65W would sound heavenly...

I've got a 65w Scumnico on the way . So far I'm digging it, plenty loud and sounds good with the ceramic blue dog. Can't wait to try the sumnico. Gonna try it out officially at rehearsal this week.

Joe, you gotta post up pictures of the cube when she's all done. Its gonna sound mean for a little amp.

My goal is to be able to fit everything for a gig into the back of a cab. I am also designing a new pedal board as well.

I will post up picture for sure. Please give a full tone report on that Scumnico as that is what I am thinking about putting in the "cube".

[vrswiss]

Scumnico has been installed and I am very pleased. By far the best speaker I have heard this amp through. Glad I decided to drop the coin for it as its only made me like this little combo setup that much more. No regrets at all for selling my 2x12 cab:D

[MattJ]

Hey everyone, newbie here with my first posting.

This is something I've actually been thinking about. I've got a few questions and was hoping to get some advise on this. I have a 1x12 Jeff Swanson cabinet for my 18 watt amp and I've become real interested in the Metro JTM45. The 18w is not bad, but it's just not me, I'd like something a little more aggressive. The Swanson cabinet I have is a custom order that's all mahogany. I'm planning on finishing it myself in a faded cherry color. Looking at it, there is some room where the chassis bolts to cabinet where I could do some sanding to make more space. It's a great cabinet and I'd hate to have it just sitting around so I'd like to try to place the JTM45 in it. Some of the things I am needing to know before I do anything are:
- What is the height of the completed JTM45 chassis from the bottom to the top of the tube when it has KT66s vs. EL34s? Just from reading this thread it looks like the EL34s would be smaller but I'm curious if anyone has measured it with KT66s.
- How close can the top of the power tubes be to the speaker baffle board before heat becomes a real worry? I certainly don't want my amp to be a fire hazzard!!
- Will there be a noticeable size difference if I upgrade to the Mercury Magnetics transformers over the standard one?
- How is the Scumnico 65w in terms of size? Right now I have the Celestion G12H 30, but I just don't think it can handle the full drive of the JTM45. The Scumnico seems to be a popular choice for the 45.

Thanks for your suggestions on this, I'll be looking on the board for some more info and let you know how it goes.
- Matt J.

[Joe Popp]

Welcome to the forum Matt J.!

The height of a JTM45 with KT66 tubes is right at 7.25" with a braided style retainer (see pic below). I am not sure what a safe distance is but I had it in a small box plexi cabinet that was 9" high. There are other factors with a combo like the front valance and speaker may interfere with things. Currently Jeff Swanson is building me a really small cab as I said above. It is 20" x 20" and 11" deep just so there are no problems.

Specs for the Scumnico from the Scumback site:
12-1/8" diameter, 6-7/8" deep with bell cover installed, 5-7/8" without bell cover.

I have built amps with Mercury Magnetics and without. They are very high quality and I believe that the OT makes a big difference over a low quality OT. My current JTM45 has Marstrans in it and I love those as well. I have heard nothing but good things about the transformers available from Metroamp but have never tried them myself.