Did the Jake E Lee mod to my Marshall JMP…

  • Thread starter Thread starter RedPlated
  • Start date Start date
psychodave said:
Yeah, it sounds cool. I'm curious if 10 volt diodes/transistors would really fill out the bottom end.
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I'm going to experiment with different values. I was thinking 12v. I have some I really like. The bottom is pretty big and punchy as is in the room. I really need to get that mic pre for the iPhone that LPFreak recommended.
 
psychodave said:
Yeah, it sounds cool. I'm curious if 10 volt diodes/transistors would really fill out the bottom end.
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This style of clipping circuit is different than the pre ts clipping style where the signal runs in series, I haven’t played with it for a couple years but I remember changing the compliance resistor value (normally 10k) had a greater effect than the diodes.

Amp sounds great J 🤘
 
RedPlated said:
I used 20v zeners. I will try MPSA06’s also. I have a decent variety of diodes down to 6v or so.

Here is the same amp with the SAT switch added. Gain is now a push-pull to engage the SAT circuit. No extra holes anywhere, total stock look.

I started clip with SAT off. Gain at 6-7. Then bump gain to 8-9 to show how it fills out the lower frequencies.

Further in the video, I engage the SAT and lower gain control back to 6-7. You’ll hear the volume drop and adjustment to MV. This is at totally reasonable volume. MV is around 1 on dial.

Les Paul again with Suhr Aldrich.

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I know you dont want to hear this because we are already discussing what to do on my other amp and I am new to working on stuff but I have a 1980 JMP that I want to do these exact things to, with SAT. So....... I guess Ill be asking lots of questions to get this done.

Also, your logo is smaller than mine. Mine is the larger Marshall logo, whats the difference?
 
I like the sound I’m hearing on these type mods on JCM/JMP. Raw, little more gain and aggression. Tighter, more responsive to subtleties in playing. This JEL mod sounds a lot like the SIR #36 mod to me.
 
Cap217 said:
He said that the depth pot if replacing the 220k//.0047 would be a 1meg linear but everything I have read says use audio. Why is that?

@ 18 minutes in
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I use audio taper for depth. Always have. Linear work too, but I just prefer audio taper.
 
You don't necessarily need to "mod" an amp to get those tones.
Jake played Marshall channel switchers with a bunch of rack gear on Bark tour.
 
Samhain said:
You don't necessarily need to "mod" an amp to get those tones.
Jake played Marshall channel switchers with a bunch of rack gear on Bark tour.
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I saw that tour and Ultimate Sin. On Ultimate Sin show we saw, he was using a single channel Marshall and one of those Boss pedalcase pedalboards with some Boss pedals.

Saw him with Wicked Alliance and he had 5 5150 stacks and they were all cranked...medium size club. Yeah he was loud!
 
RedPlated said:
I’ve had this 1980 JMP for years. All stock except for a Metro loop in the factory speaker jack holes. I saw Jason from Headfirst had posted a video with schematics for the JEL mod. Credit to him for the specs.

I decided the mod sounded like a great plan for this amp. And it’s fully reversible. I also changed the input to a ground-shielded coax cable. The stock hot shield kills treble and adds flubby bass.

I’m extremely impressed by this mod. The amp sounds like a great Marshall should. Just enough gain and good frequencies.

I made a clip last night at bedroom volume. Gain is around 6-7 on the dial. It fills out more at higher gain levels due to the bright cap still in place. I like it here for more cut.

Les Paul with Suhr Aldrich into a Cameron 4x12 with G12H30 anniversaries.



I added a VFE Standout to the front end and switched over to a different Les Paul with Throbak SLE-101+ and got this:

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Sounds beautiful, doesn't need a boost for my taste. :D
 
psychodave said:
From my own experience, change the gain pots impedance changes the tone as well as feel. The lower the pot, the more mids and funky feel. Fortin actually uses/used another pot instead of a fixed resistor for his “feel” knob… which solely changed the gain pots impedance.

I’m asking these questions since I really like this mod and am considering trying it out on master volume 2204 amp clone I own.
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It changes the pot's impedance but also simply dumps some signal to ground, reducing gain. Ceriatone uses that 82K on a push/pull. Fortin uses a 68K hardwired in the Meshuggah and sometimes a pot in his earlier mods. The higher the resistor's value, the less signal gets shunted. Also... the next stage's input grid resistor value matters when you add this "feel" control/resistor. They do play off one another. And for best results, it's important to tune the two values. When you mod something here, you sometimes need to adjust something there.
 
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