Which 2x12 for JTM45/JMP50?

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young flower
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Which 2x12 for JTM45/JMP50?

Post by young flower » Tue Apr 24, 2012 8:26 am

Hi

I recently bought a JTM45 (my first tube amp ever) - but probably want to switch to a Metro JMP50 in the near future.
Now, I still need a box and want to get a 2x12 (because 4x12 is too big for my flat and for transport).

My questions are now:

-Should the back of the box better be closed or open?
-Which impedance should it have (4,8,16 Ohms) - does it even play a role for the sound?
-any other important things to pay attention to when choosing a box for a plexi-type amp?

Thanks in advance!

YF

young flower
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Re: Which 2x12 for JTM45/JMP50?

Post by young flower » Wed Apr 25, 2012 9:43 pm

Nobody?

Another question: Which 2x12/which speakers can get bright nice clean sound with a JTM45 as well as good distortion?

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Re: Which 2x12 for JTM45/JMP50?

Post by Jef » Fri Apr 27, 2012 1:42 pm

I think it may be that your questions are a matter of personal preference, more than anything. For instance, 'open or closed' depends on the speakers you're using, the size of the cab, your room, and where the amp is in the room. And then it's simply a matter of taste.

You might get more answers asking, "Who uses a 2x12 with a JTM45?" and then asking questions of the people that respond.

BTW, in many cases 8 and 16 ohm versions of the "same" speaker do not sound the same. You can see this on the Eminence website, where they're listed separately and the T-S specs are quite different for some models.

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Re: Which 2x12 for JTM45/JMP50?

Post by johniss0001 » Fri Apr 27, 2012 10:18 pm

This is a subjective one. At the moment I have a jtm45 bluesbreaker combo running kt66 into an open backed 2x12 with 2 G12M reissues and that amp sounds really really good after my upgrades as it was a stock marshall RI. 2 G12Ms have a total of 50 watts RMS output and a jtm 45 is actually around the 50 watt mark at breakup i don't use pedals with this amp not yet but i would be careful as you are close to the edge of what they could handle.

Open backed cabs are not as punchy, this amp is quite punchy but not as punchy as it would be if it was a closed back cabinet if i am making sense. Open backed cabinets are more suited to alnico speakers I would love to try celestion golds in this amp to see how it sounds.

Closed back cabs are my favourite to be honest as i play bass with a jtm45 as well i don't have to worry about loss of low end and again that punch but i would not use G12M unless they were 55Hz for bass guitar.

As a rule of thumb generally i use speakers with double the power of the amp so you have more headroom and if you want to use pedals you don't have to worry as much about blowing speakers.

If you can find them i suggest the goodmans audiom speakers they are punchy and have a really nice bite and they wipe the floor with celestions to be honest and they have the same frequency range as a G12 65 also they came out before the 65 and can be used with bass guitar if you so wish.
John Ross

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Re: Which 2x12 for JTM45/JMP50?

Post by neikeel » Sat Apr 28, 2012 6:45 am

You quite like the psychadelic, trippy rock with lots of fuzz and some effects and delay sounds.

A JTM45 is more like a 30-35watt amp with tube rectifier and in standard guise running KT66s. A solid state rectifier may give a smidge more.
A JMP 50 in good nick will put out 50w RMS before clipping and probably 70w or so when cranked or kicked with a front end boost pedal.
So in a Bluesbreaker combo the stock G12M greenbacks will be fine. If you were to run a JMP50 and are not into thrash metal you could get by with G12Hs which are 30w speakers. They are more sensitive than G12Ms so you will have more clean headroom and will be a lot louder.
I run a pair of G12M 20w in one 18watt combo and a Scumback 55H30 in the other, a pair of G12Hs in my JMP50 combo and a pair of original alnic blues in my AC30. I have a JTM45 combo that I will be throwing together shortly and will be using a pair of Alnico Golds in that. They are all open back. That gives a good all round spread of sound and has the benefit of being able to point it at the wall in a small room to allow you to get loud in enough for the amp to be cooking but not being too loud.
Nowadays being too loud is the issue. I love my 4x12s and whenever I can justify it I gig with one but the combos are getting more use. A good compromise if you like the sound (and projection in a room) of a closed back 4x12 then a closed back 2x12 maybe for you.
Note that you can get convertible cabs with three piece backs so you can remove the centre panel to convert to an open back if you want (I believe you are in Austria so TAD in Germany do sell new versions of these but their speakers are expensive c/w UK prices.
Neil

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Re: Which 2x12 for JTM45/JMP50?

Post by johniss0001 » Sat Apr 28, 2012 7:06 am

well put neil that's the best way to describe it
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Re: Which 2x12 for JTM45/JMP50?

Post by young flower » Sat Apr 28, 2012 1:35 pm

Yes - my question was phrased somewhat ambiguously - sorry for that.
Thanks for all the advice guys!
Well Neil - You really have been a great advisor: Thank you very much. I hope I can pay you back for that in the future!

YF

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Re: Which 2x12 for JTM45/JMP50?

Post by johniss0001 » Sat Apr 28, 2012 1:43 pm

everything is subjective you just have to go and try a couple of boxes for yourself but a good one is a removable section on a closed back cab so you can compare whether you like it closed or open backed.

Personally i am not an openbacked person cause i play bass as well through my gear, i have a fantastic 2x12 i got from neil years ago and that is a closed back cab i had loaded with celestion powercells for a while, and i had loaded with goodmans and for guitar it was pretty punchy and with bass it was nice and smooth with a 50 watt valve amp.
John Ross

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