Questions about JTM45s

[Elvis2]

Okay, im about to buy a Marshall JTM45 head and 1960AX cab with celestion greenbacks and i have a couple of questions.

Is it possible to remove output tubes and reduce the wattage/volume?
I seem to recall somebody mentioning that this was possible with some Marshall tube amps but im not entirely sure.

I really like loudspeakers with alnico magnets, is it feasable to have say one side of the cab with greenbacks and replace the greenbacks on the other side with either old Jensen alnico speakers or celestion alnico blues? I once had 2 different types of speakers in a 2X12 combo amp and it didnt sound good at all but i was thinking one side greenbacks / one side alnico might be worth it for recording purposes.

A friend of mine has two JTMs from the 1960s and they sound amazing, the one im buying is a recent model but how much actual difference is there between the new ones and the old ones?

[Jonny]

If you have an amp that runs valves in parallel (e.g. 4 EL34 output valves) then yes, you can remove one of each pair, but you'll need to run the speaker output into a cab of twice the amp output's impedance (e.g. 8 ohm amp output into 16 ohm cab). I've done it before but bear in mind that 50 watts isn't that much quieter than 100watts.

[dogface]

What Jonny says is absolutely correct, however it doesn't apply to your amp because JTM45s have only one pair of output valves, so you can't remove one pair (or you'd have none left!).

[hywelg]

Originally Posted by Elvis2

A friend of mine has two JTMs from the 1960s and they sound amazing, the one im buying is a recent model but how much actual difference is there between the new ones and the old ones?

Quite a lot,

This from Mercury Magnetics site will tell you loads

If you want a clone of the orignal go here. Best amp company for value and service. Ask around you'll struggle to find anyone who's less than fully happy with any amp bought from there. I've got two and just about to order a Plexi 50 clone.

[shugz]

JTM45's are slightly different and the '45' part has nothing to do with the output wattage, it's more like 30w to be honest. That said, from a JTM45 it's a heck of a nice 30 watts

To be honest, I'd just invest in a good dummy load/ attenuator if it's too loud for you. That way you can crank it and not damage the ear drums too much. You can also mix and match you speakers too provided you get the ohm-age correct and don't overload them. That said, with a JTM45 and a 4x12" you are not pushing that much through them so a full house of alnico Blues should be fine or do it as you said, 2 Greenbacks, 2 Blues.

With regards to differences of 'new' JTM45's, it's basically a completely different amp BUT I personally think the new ones still sound great and quite close for a mass produced amp. As the link states, you can see how much of a difference there is and there's a bit of a cottage industry in modding new JTM's to make them more like the older ones. Personally, I wouldn't bother as the new JTM's sound very good BUT each to their own and if you fancy a project then there's lots to do in terms of getting a new JTM like the old ones.

Cheers
Hugh