What if.... (Marshall JTM 45 question)

[C-Martin]

...i changed to tubes (5881) of my amp to EL34's? Would it work or would it break everything or would it not sound good at all... i ask this cuz i recently tried a 1959 and 1987x Marshall and i think i like the sound of those more than mine. I also then to like 6L6's too but i think id prefer EL34's.. i dont know crap about amp electronix exept the very basics so im just wondering if people have tried this and if its possible and would the results be good. Ive heared the 5881 are often swaped for better quality sounding tubes and this is something ive been pondering for a long time

 

[Mephis]

Re: What if.... (Marshall JTM 45 question)

You'd get more mids and lose some bass.

 

[the guy who invented fire]

Re: What if.... (Marshall JTM 45 question)

You'd get more mids and lose some bass.

It's not just that simple...

for starters you would have to have the power tube sockets rewired for EL34's and have the bias set.

The thing is that a JTM-45 and a 1987 are not night and day amp but the differences between them make for a pretty large tonal change...if all you changed were the power tubes it woudl still sound mostly like a JTM-45 but w/o some of the glassiness that comes with a JTM-45 on clean settings and the breakup character would be quite different. If you wanted to get a little closer to the 1987 you could swap the power tubes for EL34 and put in a SS plug in rectifier...it still isn't gonna be a 1987 but it would be closer.

All that said if you want the crunch tone of a 1987 or a 1959 sell the JTM-45 and get the 1987...you could mod it to be a lot closer but it's on a PCB (I assume it is a reissue) and would simply be a lot more work and trouble that it would be worth...

 

[Stratman]

Re: What if.... (Marshall JTM 45 question)

I agree with the guy who claims to have invented fire.

Changing power tubes is not a simple, plug and replace.

The circuit, current draw, etc has to jive in order to work.

 

[Scott_F]

Re: What if.... (Marshall JTM 45 question)

Well, I'm not sure but if the amp was wired right when it was built, it could accept EL34's. It's just a matter of wiring the grounds correctly on pins 1 and 8. It should not take a tech that long to do it and then bias it up. It will take a different bias resistor. Total work time 30-60 minutes on a hand-wired amp. Might be a bit longer if the sockets are attached directly to some cheesey circuit board.

 

[kevlar3000]

Re: What if.... (Marshall JTM 45 question)

It may be that you like the response of a non tube rectified amp. Ted Weber makes a very cool product called a copper cap, it plugs in to the rectifier tube socket. It will tighten things up, definately give a quicker jump on the note and make the amp louder. I have it in two of my tube rectified amps, I was curious, tried em out and really liked what they did for those amps. He also makes a version that does simulate the sag of a tube rectifier... Very cool gadget, www.webervst.com

There are lots of flavors of 6l6 that might be worth looking into, lot of the newer stuff I have heard is stiff with brittle highs. Shuguang makes a great sounding 6l6, TAD is one name they are branded under. The small bottles have a really smooth top and round bass. Beyond that, vintage may be a way to go, if you shoot terry_kilgore2003@yahoo.com a note, he could set you up with a batch of great sounding tubes. You tell him what you are shooting for and he will get you the goods, best prices on the net.

Finally, it is very poss that you have an amp with the bias set too cold, that will suck the tone out of just about every amp...

 

[Lake Placid Blues]

Re: What if.... (Marshall JTM 45 question)

Marshalls are usually wired from the factory, such that you can go to EL34 or 6L6, without re-wiring the sockets.

Another option is to go to KT66. KT66's are still a 6L6 family tube, but sound big and Marshally. KT66's are the original JTM45 tube, and a proven up-grade to the re-issue amps. This may be less of problem from a setting the bias standpoint.

 

[Gr8Scott]

Re: What if.... (Marshall JTM 45 question)

+1 to KT66's. Definitely the way to go with a JTM45. Gives the best of both worlds. Beautiful cleans and really sweet distortion. Ask me how I know? :banana:

 

[stevie_bees]

Re: What if.... (Marshall JTM 45 question)

+1 to KT66's. Definitely the way to go with a JTM45. Gives the best of both worlds. Beautiful cleans and really sweet distortion. Ask me how I know? :banana:

No

 

[Scott_F]

Re: What if.... (Marshall JTM 45 question)

Weber copper caps are supposed to simulate real tube rectifiers in terms of ramp up and similar voltages. I've used one once and went back to tubes mostly for aesthetics reasons. Some companies make solid state rectifier plugs that actually increase the B+ voltage levels.

 

[C-Martin]

Re: What if.... (Marshall JTM 45 question)

+1 to KT66's. Definitely the way to go with a JTM45. Gives the best of both worlds. Beautiful cleans and really sweet distortion. Ask me how I know? :banana:

im guessing you have a JTM-45 you upgraded with KT66? and from what im reading its to much of a hasle to switch to el34's... AND i would lose part of the JTM sound that i like... maybe better 6l6 or kt66 would make it sound better tho.. i do kinda like its "glassiness" like one of you said, its kinda the sound im trying to get more of out of my new les paul

 

[Gr8Scott]

Re: What if.... (Marshall JTM 45 question)

The KT66's don't break up as early as the plexi does, but when it finally goes, it's really sweet. I think Angus Young uses KT66's for his signature sound and I can replicate that almost to perfection with my JTM45 with KT66's using a humbucker equipped guitar or a strat with a boost pedal. Its loud but it rules tone wise IMHO.

 

[Lake Placid Blues]

Re: What if.... (Marshall JTM 45 question)

Marshall is using KT66's in the new Vintage Modern (2266) amps. I thought the youtube clips sounded pretty good.