JMP preamp tubes

[sheikyerbouti]

Just scored a 76 JMP and love it. It has some nice sounding GE 12ax7's in it and I'm wondering if I can get a tube which can produce some additional gain.

Seems many folks like Mullards, but I'm not sure if these are the newer ones for ~$18 or NOS at $$$.

I wasn't a huge fan of the JJ's from Eurotubes I put in my Shiva.

[TELECOLLECTOR]

I am, admittedly, no expert - on damn near anything - just ask my wife:aok

However.

I snagged a '79 JMP (2204 50w Master) in all original condition last summer.

The previous owner had just had the amp looked at and the tech re-tubed everything using GT's. So the whole tube set is fresh.

I have quite a number of vintage Fender amps and asked Mike at KCA for some recommendations for them and mentioned I wouldn't mind trying something new in the preamp of the Marshall too.

He suggested I try some NOS RFT 12AX7's.

I received the tube package yesterday and had a few minutes last night to swap the tubes out and plug in.

There is a very noticeable difference to my (slowly fading) ears.

Sweeter, smoother, less sharp perhaps?

I am just trying to get my feet wet regarding NOS (and ANOS) tube's.

I look forward to playing with my Fenders today and swapping in the NOS RCA into a few and seeing differences.

Best of luck with your Marshall - great amps and a real bargain in my opinion..............

[rockon1]

Have them tested for high gain from a reputable dealer. Bob

[rob2001]

Just scored a 76 JMP and love it. It has some nice sounding GE 12ax7's in it and I'm wondering if I can get a tube which can produce some additional gain.

Seems many folks like Mullards, but I'm not sure if these are the newer ones for ~$18 or NOS at $$$.

I wasn't a huge fan of the JJ's from Eurotubes I put in my Shiva.


I'm assuming this is a non master JMP, but to be honest, you won't find much more gain from a different set of tubes. Sure, slight tonal differences but not much more gain IMO.

I had a '77 non master JMP and a dirt pedal out front was the answer. I don't care for attenuators and even cranking that amp didn't bring it up to JCM 800 type gain, which still isn't high gain.

[stump]

Sylvania, Tungsram and RFT are my first choice, besides Mullards, in V1. For new production I find Tungsols work well, just be careful in V2 as they don't seem to handle the voltages in that spot in Marshall's.