Suggestion for Jose mod on JMP

  • Thread starter Thread starter musicman93x
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zz666 said:
It’s his Marshall (with EQ pedal) and Charvel. He got the 5150’s for the tour
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Well while I am sure he used his 69 JMP with the charvel loaded with a JB on Jerusalem Slim I am not sure even if he used the same on Exposed.
I read in another forum he stated it, so I trust him. The whole down tuning and boosting an old JMP should get there. We know for certain it was a 69 plexi face, so its closer probably to a very first 70s Marshall with higher voltage and a 0.68 on V2. However we don't know if they were 820 or 2.7k at V1.

The 5150 was used live but I believe not for the record. I know that Steve also had an Soldano SLO 100 as all of the who is who in the industry had one.

But when I listen to Steve's guitar I still hear that ratty high end like on a cranked Super Lead that turns right about into fuzz territory.
 
Chubbs said:
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…
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That would be best. But I know for sure Ill be tempted to leave the amp open with the soldering iron next to it while playing.
I am gonna do 3-5 changes every time while putting the amp back together to my guitar room. Otherwise Id kill myself. I know Id be that stupid. :/
 
My advice is to start with the extra gain stage in front, and put the new master volume post tone stack like a 2203. Get that going, and then consider rewiring with the diodes for a pre tone stack Jose master. Pre tone stack masters require more skill and experience to get a result, as the amp becomes very prone to noise and signal bleed….unless you know what you’re doing.
 
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musicman93x said:
Thank you for this information about the filter caps! I didn't even notice.
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The HW’s I modded were from 2022 and 2023. I don’t know if they did that with the filter in earlier years. I’d be curious to know how far back that goes. Let us know how yours is wired and what year it is.
 
RedPlated said:
The HW’s I modded were from 2022 and 2023. I don’t know if they did that with the filter in earlier years. I’d be curious to know how far back that goes. Let us know how yours is wired and what year it is.
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Ill post some guts very soon.
 
Techdeth said:
I still believe it . I been told differently. I don’t hear a Marshall at i but I get people still say that
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Also he started the Vince tour with his Marshall’s til Ed saw them and said they’re too valuable to tour with and then gave him the 5150’s
 
zz666 said:
Also he started the Vince tour with his Marshall’s til Ed saw them and said they’re too valuable to tour with and then gave him the 5150’s
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It sounds exactly like a 5150. I don’t hear Marshall at all . But it’s whatever. But I love that tone and it’s very easy to get 5150 . A tad of boost and it’s there
 
Re: Steve Stevens Massenburg EQ?


• by StevensAGoGo > Mon Mar 16, 2015 8:49 am

From SS…
Hey Guys,


I've never owned a Massenburg EQ, and a low impedance piece of gear like that would not work well for a guitar amp. Keep in mind that the Marshall 100 watt used for Exposed and Jerusalem Slim, had no master volume back then. Basically it was just..turn everything but presence up to 10 and there ya go. Players just don't play that loud anymore, except in a recording studio sometimes. Occasionally I would use a Boss EQ in line, but mostly for solos. Much of that guitar sound is great studio rooms....great consoles....analog tape. As i still own that amp, and occasionally plug it in....there is no magic genie to it. It's a really nice old Marshall, that's all. Please remember, played bass as well on both those records....that creates another layer of what makes the guitar so tight and punchy. I think part of what sounds g@od about Exposed is the whole step down tuning on the whole record.


Thanks, Steve
 
zz666 said:
Re: Steve Stevens Massenburg EQ?


• by StevensAGoGo > Mon Mar 16, 2015 8:49 am

From SS…
Hey Guys,


I've never owned a Massenburg EQ, and a low impedance piece of gear like that would not work well for a guitar amp. Keep in mind that the Marshall 100 watt used for Exposed and Jerusalem Slim, had no master volume back then. Basically it was just..turn everything but presence up to 10 and there ya go. Players just don't play that loud anymore, except in a recording studio sometimes. Occasionally I would use a Boss EQ in line, but mostly for solos. Much of that guitar sound is great studio rooms....great consoles....analog tape. As i still own that amp, and occasionally plug it in....there is no magic genie to it. It's a really nice old Marshall, that's all. Please remember, played bass as well on both those records....that creates another layer of what makes the guitar so tight and punchy. I think part of what sounds g@od about Exposed is the whole step down tuning on the whole record.


Thanks, Steve
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And just like that, the discussion is done. What a gem of info here.
 
Hello guys. Just as promised here are some pics before, the big ass PT
20230806_162918.jpg


here is the original wiring.. no bright cap from stock 😞
20230806_163622.jpg


and after some first changes:
20230806_175813.jpg


I just worked on v1: i changed the original v1a and v1b bypass caps to old phillips chicklets 😉

The voltage divider was changed from 68k/68k to 68k/100k . This is what you also see in the Friedman JJ and SS. Which makes those amps thicker. The old BE100 still has 68k/68k. I just went with the suggestion of Jason Tong in his 1959 jose stealth mod video.
I will play around and see if I can make it on a switchable because I am temped to try this switch even on my Friedman SS 😀. I will never sell this amp anyway so what the heck.

Then the 100k plate resistor was bumped up to 320k with a 220k in series. This adds also good bit of gain.

Also the first coupling cap was changed from 22nf to 2.2nf. As opposed to Jason Tongs video in my amp these two coupling caps were just switched! He said in the Marshall 1959 HW he got both were 22nf.. well not in mine.

After that I will change the wiring from parallel to series in order to cascade v1a and v1b. Adding some plate snubbers here and there and the pre tone stack master with some shielded wire.

The diodes will have to wait a few weeks until I can source the right ones for this job.
 
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RedPlated said:
The HW’s I modded were from 2022 and 2023. I don’t know if they did that with the filter in earlier years. I’d be curious to know how far back that goes. Let us know how yours is wired and what year it is.
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This is how the electrolytic caps are wired. Currently the amp uses tube amp doctor caps.. i hate anything else then ARS or FT Radials. The amp also ghosts a bit. With the g or d string on around the 8th to 10th fret.
20230806_163634.jpg
20230806_163627.jpg
 
Yep. Same as the ones I had here. Your PI filter is only wired on one side. Just connect the yellow terminal to the red one and you’ll double the filtering. Will help with the ghosting.

I prefer ARS as well but I don’t hear anything wrong with the TAD’s. I wouldn’t go as far as to replace them.

You_Doodle_2023-08-06T21_05_13Z.jpeg
 
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Thank you @RedPlated. Does this also do something else with the sound?
I pretty much like the fuzzyines with the amp on 10 when the highs kick into fuzz overdrive. I makes it sound so wild and late 60s style.
Does it disapear or just help with the ghosting?

I don't see a way to put this small connection on a switch to compare 50uf vs 100uf on the PI as there are 500V running through.
Has anyone done that before?
 
musicman93x said:
Then the 100k plate resistor was bumped up to 320k with a 220k in series. This adds also good bit of gain.
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540k plate load is very high. Like higher than I've seen anybody use (and I've tried it all). It will drop your plate voltage too much and can cause some issues if it goes below 160v on V1a. The amp will be super fizzy and loose (not in a good way). But maybe you want that kind of thing. You can do what you want, but personally... I wouldn't go higher than 320K. Especially if you run 820R cathode on either the first two stages.

musicman93x said:
Also the first coupling cap was changed from 22nf to 2.2nf.
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Another potential issue. Many get this wrong. Well, "wrong" is subjective. But you might consider experimenting with which of the first two coupling caps is 22nf and which is 2.2nf. The order is important but will also depend on a few other things in the circuit and how much bass you want to let through to each stage.

musicman93x said:
After that I will change the wiring from parallel to series in order to cascade v1a and v1b. Adding some plate snubbers here and there and the pre tone stack master with some shielded wire.

The diodes will have to wait a few weeks until I can source the right ones for this job.
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What voltage zeners do you plan on using?
 
Making the PI cap 100uF will make the dynamics a bit less spongy. Firmer feel to the low strings etc… It’s not going to be a totally different amp, but it’ll make a difference. It should help the ghosting.

How I would do it is flip the chassis upside down and alligator clip across those terminals. Then take the alligator clip on and off to hear and feel the difference. Make sure to turn off and unplug the amp before you move the clips. And….these amps hold voltage on the filter caps for a long time. They discharge slowly. Draining the caps is a good idea before moving the clips. Otherwise you risk the shock of 450+ volts dc.

Only do the above if you are experienced and know the dangers of amps and high voltage.
 
Interesting that they used 560pF for both the Treble cap and peaker cap. @musicman93x if after you've done your mods you have room to tweek there. It may be perfect as is but I tend to fatigue on too much mids...it sounds great at first but then it starts to sound a little honky or squawky. Maybe its due to old ears and the ringing. But sometimes 560pF is perfect.

Cool info about SS. His tone on those records is great. My favorite kind of sound.
 
SpiderWars said:
Interesting that they used 560pF for both the Treble cap and peaker cap. @musicman93x if after you've done your mods you have room to tweek there. It may be perfect as is but I tend to fatigue on too much mids...it sounds great at first but then it starts to sound a little honky or squawky. Maybe its due to old ears and the ringing. But sometimes 560pF is perfect.

Cool info about SS. His tone on those records is great. My favorite kind of sound.
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Ill probably leave the 560pf treble caps. In fact I also changed both the 500pf in Suhr SL68 to 560pf and didnt notice too much.

560pf was in most marshalls in 1969 as well as the red dogbone 47pf PI fizz caps.
 
Hey @FourT6and2 I am not really sure on which diodes I will use.. I am aiming for a more subtle diode clipping as I like the rawness of marshalls and its enough compression for what I play. Also I don't like to much of a voltage drop. This would need to incorporate a second master imo.

Maybe Ill try the same zeeners like in the Jose stealth mod video first and adjust from there:
 
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