Suggestions to upgrade my amp?

[Nico 666]

Hi everyone!
Here is my problem.
I've got a Marshall JTM 610 I've been playin for ten years.
It always served me well but I've been feeling like modding it for a while.
It is a two channels combo with 4*12AX7s and 2*EL34s and 3 Eminence 10" speakers.
As I have now another amp to cover the clean sounds, I'm thinking to make it a crunch/lead amp only.
So I need to make the channel 1 break up earlier to obtain a "BluesBreaker" sound.
As for the channel 2, I'm pretty happy with it now except that it is a tad too harsh for me, even with my Les Paul (SD '59 neck and JB bridge). So, I need to smoothen it a little.
Any suggestion welcome, whether it concerns the tubes or the speakers.
I don't really know where to go.
Thanks
Nick

[Curly]

Re: Suggestions to upgrade my amp?

Nico,
I'm not a Marshall expert, and not familiar with that circuit, but in general, the first position preamp tube (V1) determines the overall gain of the first channel, and the second determines gain for the 2nd channel.

Changing your V1 will have the most effect. Depending on your budget, a lot of Marshall players say they like JJ's for current production tubes, and Mullards for NOS. (The JJs usually have a higher gain that's closer to the old tubes than some other current 12AX7s). Another current production tube to consider is the new GT 12AX7M "Mullard" reproduction.

Besides the advice of others here, I'd recommend a post over on the Expert forums. Myles can give you tube by tube recommendations.

Include information regarding the tubes you have now, as well as the model of speaker.

[aleclee]

Re: Suggestions to upgrade my amp?

Upgrading the preamp tubes might help a bit with the harshness. I've had good results with the GT 12AX7Ms. Though they're pricey for a preamp tube ($26 list), one of these in your first preamp tube position might smooth things out a bit.

As for earlier breakup, the only things I can think of are less efficient speakers or an attenuator. That way, the amp is working harder at a given volume level.

[Benjy_26]

Re: Suggestions to upgrade my amp?

Softer power amp tubes might give you more breakup into your sound. My current pick for production EL34's are the ElectroHarmonix. EH makes an excellent power tube for the money that sounds very much like the NOS tubes I've tried. Their EL34' beat the snot out of the Siemens tubes I had in my Convertible 60 and their 6L6 blackplate copies sounded very close to the RCA's I had in my Bassman, if a tough brighter. Try them out if you can.

[Nico 666]

Re: Suggestions to upgrade my amp?

Thanks all you folks!
I have a way to go now!