First Amp Mod - JCM800

Inspector #20

Inspector #20

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This one is owned by Rat's Nest Studios. They want me to clean up some of the solder joints and add a Lynch Mod Unit to it. I plan on shielding some of the coax cables that are bare and run really close to powered connections.

Amp 1.jpg

Board.jpg

Top Soldering.jpg

Morin Phone Redacted.jpg

I suppose it's no wonder that Mike is selling real estate these days...

Here's the rundown on the LynchMod:

"Created in collaboration with George Lynch, the Lynch Mod is a custom modified version of the Hot Mod V2. Want to supercharge your classic Marshall amp with more gain without applying a permanent modification? Then read more below and welcome to the Lynch Mod!

George tried the original Hot Mod V2 (HMV2) in his Marshall and enjoyed it, so we decided to collaborate and do a custom-voiced version specifically for him. So instead of the HMV2’s two-position Hot Switch for two pre-set gain stages, we’ve added a gain knob that goes from unity gain all the way to scorching hot on the Lynch Mod. And just like the original HMV2, all the clarity and low-noise characteristics have been retained. We also added a Deep switch to help provide a bass boost when desired or when using a guitar that might otherwise be a little thin. With the Deep switch off, low end is tightened and it serves as a slight bass cut for clarity.

The Lynch Mod adds an adjustable 100% pure tube gain stage on top of the cathode follower V2 position, keeping note definition and articulation while further increasing sustain. As with all previous runs of Lynch Mod units, each is meticulously built and wired by hand, point-to-point, and tuned using high-grade materials. Equipped with a single JJ ECC81 (12AT7) in the first position and JJ ECC83 (12AX7) in the second, the Lynch Mod adds a gain stage to your Marshall that’s been tuned and approved by the ears of the maestro George Lynch himself..."



Here's an image of the Lynch Mod device:

lynchmod.jpg
 
syscokid said:
I wouldn't be able to resist the urge to pull all the resistors with paint on them... Then test & document each one for actual resistance values... Then replace them with brand new ones. Then do the same thing with the caps, too!

What's with that humongous sized cap on the Presence pot?

View attachment 76201
Click to expand...

No one is really sure!!!!

He added a gain stage and FX loop, but he went to great pains to try and "hide" all the values.
 
Robert Herndon said:
The amp works fine and is quiet, it just doesn't have any real pizzazz.....
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Well, it is a 100 watt amp. The amp's power section needs to be driven for the good stuff to come out. I know that the volume will be insane, but does it ever get used like this?
 
Robert Herndon said:
The amp works fine and is quiet, it just doesn't have any real pizzazz.....
Click to expand...

Real question here, from a lover of JCM-800s: Why would anyone mod an amp in that condition that doesn't have "it" instead of buying an amp that already does what they want it to do? I mean, if it's just gain or some other quality in the saturation there are plenty of amps out there that have it in spades vs. an 800, including a number of modern Marshalls.

syscokid said:
Well, it is a 100 watt amp. The amp's power section needs to be driven for the good stuff to come out. I know that the volume will be insane, but does it ever get used like this?
Click to expand...

For sure. The magic in an 800 is with it working the power section hard. When I gigged one I used the 2205 because I could actually get it up loud enough to where it sounded good. A 100-watter would have blown everyone off the stage by the time the power section started giving up the goods.
 
That amp looks like a dump run. Lucky when I lived in LA my guitar teacher turned me on to Billy Zoom for my guitar amps
the thing about Billy's work you can't tell it was modified looking at it but the sound fantastic. not a hack like that Jose.

www.premierguitar.com

Builder Profile: Billy Zoom Music

The legendary X guitarist dishes about the trials of balancing a busy touring schedule with the demands of his amp business, and shares his latest designs for Gretsch, the Black Crowes, and Brian Setzer.
www.premierguitar.com www.premierguitar.com
 
gball said:
Real question here, from a lover of JCM-800s: Why would anyone mod an amp in that condition that doesn't have "it" instead of buying an amp that already does what they want it to do? I mean, if it's just gain or some other quality in the saturation there are plenty of amps out there that have it in spades vs. an 800, including a number of modern Marshalls.



For sure. The magic in an 800 is with it working the power section hard. When I gigged one I used the 2205 because I could actually get it up loud enough to where it sounded good. A 100-watter would have blown everyone off the stage by the time the power section started giving up the goods.
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Not sure...
 
67plexi said:
That amp looks like a dump run. Lucky when I lived in LA my guitar teacher turned me on to Billy Zoom for my guitar amps
the thing about Billy's work you can't tell it was modified looking at it but the sound fantastic. not a hack like that Jose.

www.premierguitar.com

Builder Profile: Billy Zoom Music

The legendary X guitarist dishes about the trials of balancing a busy touring schedule with the demands of his amp business, and shares his latest designs for Gretsch, the Black Crowes, and Brian Setzer.
www.premierguitar.com www.premierguitar.com
Click to expand...

Not everyone has your budget...

@syscokid's work is impeccable. Some of the cleanest work I've ever seen...
 
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67plexi said:
That amp looks like a dump run. Lucky when I lived in LA my guitar teacher turned me on to Billy Zoom for my guitar amps
the thing about Billy's work you can't tell it was modified looking at it but the sound fantastic. not a hack like that Jose.

www.premierguitar.com

Builder Profile: Billy Zoom Music

The legendary X guitarist dishes about the trials of balancing a busy touring schedule with the demands of his amp business, and shares his latest designs for Gretsch, the Black Crowes, and Brian Setzer.
www.premierguitar.com www.premierguitar.com
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It does look hacked up...I hate to say it but.
I think I could make it sound better without adding any extra tubes.
 
Robert Herndon said:
Not really.
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You would be amazed what happens when you bypass the tone controls...
take a tip from Alexander.
You know, as simple as his ideas are he seems to get better results than anybody who adds gain stages.

I'm becoming convinced that adding more and more gain stages is doing nothing to improve the sound...
But it does seem to add a lot of noise and a lot of mud.
I'm thinking the Randall Smith approach is one I like to avoid.
 
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I think I would start by maybe doing as Sysco suggested in documenting the changes that have been done to it, but then I'd probably put it back to a stock 800. It appears to have the original transformers, which is a good thing. I'd best not comment on added tubes positioning. Correct Piher type resistors are easily obtained & not too expensive. Year of manufacture would dictate what type caps "should" be in there, Philips KT-347 series (radial leaded) mustards, Chicklets etc etc, if you wanted to go that route (I'm not a fan of orange drops in Marshalls, even the 715P series that they appear to be). If you are going to add the (hot mod) Lynch Mod, putting the circuit back to stock would be advisable, at least to start with.
A reasonable amount of extra gain can be had from the 2203/2204 type pre-amp circuit without resorting to adding tubes or bypassing (or lifting the ground on) the tone stack. The trick to doing this well is to go for small gains spread through the various stages of the pre-amp circuitry, rather than going for a large gain in one area.
It'll be interesting to see the outcome of your endeavour. Cheers
 
ivan H said:
I think I would start by maybe doing as Sysco suggested in documenting the changes that have been done to it, but then I'd probably put it back to a stock 800. It appears to have the original transformers, which is a good thing. I'd best not comment on added tubes positioning. Correct Piher type resistors are easily obtained & not too expensive. Year of manufacture would dictate what type caps "should" be in there, Philips KT-347 series (radial leaded) mustards, Chicklets etc etc, if you wanted to go that route (I'm not a fan of orange drops in Marshalls, even the 715P series that they appear to be). If you are going to add the (hot mod) Lynch Mod, putting the circuit back to stock would be advisable, at least to start with.
A reasonable amount of extra gain can be had from the 2203/2204 type pre-amp circuit without resorting to adding tubes or bypassing (or lifting the ground on) the tone stack. The trick to doing this well is to go for small gains spread through the various stages of the pre-amp circuitry, rather than going for a large gain in one area.
It'll be interesting to see the outcome of your endeavour. Cheers
Click to expand...

I'm going to do as you have suggested and study it and try and figure out what changes have been made and document them before going forward.

I do know for a fact that an FX loop has been added, and maybe the oddly placed, extra tube is for that purpose???
 
Is it possible to replace the PCB with a turret board??? Is installing a Metro-style FX loop easily done with a turret board???
 
Robert Herndon said:
Is it possible to replace the PCB with a turret board??? Is installing a Metro-style FX loop easily done with a turret board???
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Yes, and yes, but.....

It's going to take a lot of planning and a lot of tedious work. And... Would you replicate the Morin mods, or try to return it to stock?
 
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