Suggestion for Jose mod on JMP

M

musicman93x

New member
Hey guys I am going to build a Jose modded JMP from a new Marshall 1959HW.

It is my first Jose mod and I am not sure which one Id like to do. The parallel or split cathode style mod.

Ive seen a lot of instructions from Jason Tong from Headfirst amplification and have to say that he is really a top dude for information about these amps.

Current amps that I have and am happy with are a Friedman SS100, BE100, Suhr SL68. What I miss on both Friedmans is the fuzzy smeary top end when driving the master hard like it does on a old school NMV JMP. Hell even a JCM800 does it nice.

Anyway I got all the parts I needed except for the switchable diodes to start. These parts are:

Coax
Shielded Coax
Heat Shrink
500pf, 1000pf, 3300pf ceramic caps
0.68uf polyester or electrolytic caps
2200pf, 4700pf polyester caps
500M Linear Pot / Push Pull with DPDT
1M Audio Taper Pot (depth)
500pf Silver Mica
ECC83/12AX7 Tube Socket
100k, 220k, 330k, 2.7k, 820 resistors

I got most of the parts from valvestorm and mouser.

What I dont know is the power filtering scheme on these amps.. alll 50uf? Or is it also nice to go lower like 16uf on the preamp and screens?

Ill try to maintain a stock looking amp from the front but get some switchable options on the back panel for the depth circuit capacitor, NFB, and V1a/b resistor and cap values and Fat cap.

It will get the pre tone stack master. The depth circuit will utilize a 6way double pole rotary switch on the back using .0022uf to .0068uf caps each in polyester and ceramic to try different dielectrics. I heard ceramic in the depth curcuit is the way to go.

If anyone has some tips to try out I would be very happy to incorporate. Its not my first mod..I am handy with a soldering iron and know the risks and how to drain the caps before operating inside.
 
Wished I had more to order from Valvestorm last week.

Bought a potentiometer from them for $1.75.
$9 to ship to me.
I'm in NY, it came from PA.
 
The whole Motley Crue type of Marshall sound is all parallel inputs blended together. I’ve always liked that sound over the EVH split cathode type of tone myself.
 
dcburn said:
Wished I had more to order from Valvestorm last week.

Bought a potentiometer from them for $1.75.
$9 to ship to me.
I'm in NY, it came from PA.
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I get your point. I live in Germany and shipping was around 40$ for me. I always end up missing something and try to collect big orders.
unfortunately sourcing the right parts got harder after covid. I hope this is going to relieve soon.
 
Racerxrated said:
Lots of great minds here on the forum to help you.....Jose mods can sound killer. Good luck.
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Thank you! Yeah especially like those Motley Crue sounds as well as Steve Stevens on Exposed.
He claimed it was a stock 69 plexi super lead with everything on 10.
I also like Steve Vais modded JMP featured by Pete Thorn.
 
musicman93x said:
I get your point. I live in Germany and shipping was around 40$ for me. I always end up missing something and try to collect big orders.
unfortunately sourcing the right parts got harder after covid. I hope this is going to relieve soon.
Click to expand...
Man what a baby I am!
Youre a bit further than me and here I am whining about shipping... :LOL:
 
musicman93x said:
Thank you! Yeah especially like those Motley Crue sounds as well as Steve Stevens on Exposed.
He claimed it was a stock 69 plexi super lead with everything on 10.
I also like Steve Vais modded JMP featured by Pete Thorn.
Click to expand...
Exposed sounds like a 5150 . I’ve got that tone using 5150 . I don’t hear Marshall in m any way . And he had 5150s then and on that tour
 
glpg80 said:
The whole Motley Crue type of Marshall sound is all parallel inputs blended together. I’ve always liked that sound over the EVH split cathode type of tone myself.
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help me understand these statements. lately Ive been watching and reading on amplifier builds to improve my understanding of what the hell you guys are talking about... I am trying slowly to comprehend why things sound the way they do. thanks
 
I agree with GLPG, I always preferred the parallel in terms of the Jose stuff.
I’d start with the three tube setup, you might find that to be sufficient.

In my opinion it’s best to work in steps so you learn what your hearing. For example do the depth mod, fire it up and listen. Change one plate resistor and listen. So on and so on.

Then I’d do the SIR 36 mod…
 
The new 1959 HW’s are outstanding platforms. I’ve modded a couple for guys recently. I liked them so much that I bought one for myself. The lay down PT is absolutely massive. A lot of iron.

One thing to note on the HW - they leave half of the PI filter cap disconnected. So you’re only getting 50uF instead of 100uF filtering. I’d recommend connecting the second side of the cap.

I prefer 50uF all the way through.
 
Kelly said:
You're not gonna get the JMP sound from a newer 1959. Need those old transformers.
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I respectfully disagree :)

While they make a big difference, the main things to look at are the filtering scheme, type of resistors (carbon comp vs. film)
and values of the resistors as the old ones you will see they drift up easily around 20% if they were carbon.

Then the type of caps (polyester, polypropylene ,electrolytic) have different transients/reactions on certain frequencies.
I will just use the regular (ero/vishay, mallory 150). No cork sniffing here :)
Even the silver mica treble caps you see in old JMPs were going from 470pf to 560pf.

I played a few old ones and compared them and I have to say it really comes down to the guitar and your hands.
Low-output PAF-style single cut guitar and you are in classic rock heaven.. hell even with a 1959 SLP pcb board amp.
 
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Thank you for this information about the filter caps! I didn't even notice.
RedPlated said:
The new 1959 HW’s are outstanding platforms. I’ve modded a couple for guys recently. I liked them so much that I bought one for myself. The lay down PT is absolutely massive. A lot of iron.

One thing to note on the HW - they leave half of the PI filter cap disconnected. So you’re only getting 50uF instead of 100uF filtering. I’d recommend connecting the second side of the cap.

I prefer 50uF all the way through.
Click to expand...
 
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