NAD: ‘83 JCM 800 2204, Metalhead modded by Elan Memran.

Mad Axe said:
A lot of people don’t talk about it but he used that amp on this record too. The mix is much more raw than any of the Fear Factory albums and it’s probably closer to what the amp sounded like in real life.

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That’s cool, I didn’t realize that!
 
Soundstorm said:


Just the amp and a couple FF riffs here. Boosting the front end with a Dirty Tree. I read that Dino used some type of Boss to boost during the album, plus he backed off the gain and quad tracked.
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Mad Axe said:
I was on the fence about posting this but since we are talking Metalheads, here is a clip of mine from an album I’m in the middle of recording. It’s just raw drums and guitar, no EQ or processing yet. The guitar is a ‘72 SG Custom with a Bareknuckle Aftermath going straight into the Marshall.

https://on.soundcloud.com/1YC7ywReHWBP6LiW8
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Man those are sick clips! :m17::rock:
 
One of my favorite mods. I owned two of them and cloned one into an 89 JCM800 with a few tweaks and its an awesome amp. They go from clean to mean with little volume drop because of where the circuit is placed after the stock gain stages before the cathode follower. I even constructed the same pull pot he used which are impossible to find so I used a 5K and made it 1 meg by switching out the disc from a regular vintage pot of the same. After this pic I added a three stage gain boost on the two added stages and a two way sat switch. I found mine too bass heavy with the 20uf cathode caps on the added two gain stages so I dropped those to 10uf after comparisons in mine. I did not care for the bass boost in the one I owned that had it and neither had his gate. Killer amp. They are bone stock JCM 800 with the pot disengaged as no other components are swapped at all. Only difference is now shielded leads. You have to keep the preamp knob low on these mods to keep it tight with the circuit engaged.
 

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glip22 said:
One of my favorite mods. I owned two of them and cloned one into an 89 JCM800 with a few tweaks and its an awesome amp. They go from clean to mean with little volume drop because of where the circuit is placed after the stock gain stages before the cathode follower. I even constructed the same pull pot he used which are impossible to find so I used a 5K and made it 1 meg by switching out the disc from a regular vintage pot of the same. After this pic I added a three stage gain boost on the two added stages and a two way sat switch. I found mine too bass heavy with the 20uf cathode caps on the added two gain stages so I dropped those to 10uf after comparisons in mine. I did not care for the bass boost in the one I owned that had it and neither had his gate. Killer amp. They are bone stock JCM 800 with the pot disengaged as no other components are swapped aside from ad circuit. Only difference is now shielded leads. You have to keep the preamp knob low on these mods to keep it tight with the circuit engaged.
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Yeah I would like to tighten up the low end on mine without having to resort to a pedal to do that, as of now it’s a must with a baritone guitar. I’m not really an amp tech but I’m pretty good with electronics and a soldering iron. So lowering the value of those two caps doesn’t affect the stock 800 tone? Did it tighten up the amp pretty well?
 
glip22 said:
One of my favorite mods. I owned two of them and cloned one into an 89 JCM800 with a few tweaks and its an awesome amp. They go from clean to mean with little volume drop because of where the circuit is placed after the stock gain stages before the cathode follower. I even constructed the same pull pot he used which are impossible to find so I used a 5K and made it 1 meg by switching out the disc from a regular vintage pot of the same. After this pic I added a three stage gain boost on the two added stages. I found mine too bass heavy with the 20uf cathode caps on the added two gain stages so I dropped those to 10uf after comparisons in mine. I did not care for the bass boost in the one I owned that had it and neither had his gate. Killer amp. They are bone stock JCM 800 with the pot disengaged as no other components are swapped aside from ad circuit. Only difference is now shielded leads. You have to keep the preamp knob low on these mods to keep it tight with the circuit engaged.
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Soundstorm said:
Yeah I would like to tighten up the low end on mine without having to resort to a pedal to do that, as of now it’s a must with a baritone guitar. I’m not really an amp tech but I’m pretty good with electronics and a soldering iron. So lowering the value of those two caps doesn’t affect the stock 800 tone? Did it tighten up the amp pretty well?
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Lowering the value of those caps does not affect the stock tone one bit. The added circuitry is only in the circuit with the pot pulled. With the pot in all added circuitry is completely bypassed. Mine has a huge tight bass with my bass pot at 11:00.
 
glip22 said:
Lowering the value of those caps does not affect the stock tone one bit. The added circuitry is only in the circuit with the pot pulled. With the pot in all added circuitry is completely bypassed. Mine has a huge tight bass with my bass pot at 11:00.
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So I'd just look for the two 20uF caps on the extension board and replace those? I know reports vary a bit on the low end response of these so I'm guessing he changed the circuit up a bit over the years
 
Oh and I had a really microphonic tube in the added gain stage that I put in right when I got the amp (Chinese 12AX7B, I'm done with you). That's where the fizz I couldn't dial out was coming from. Sounds and feels much better now.
 
glip22 said:
One of my favorite mods. I owned two of them and cloned one into an 89 JCM800 with a few tweaks and its an awesome amp. They go from clean to mean with little volume drop because of where the circuit is placed after the stock gain stages before the cathode follower. I even constructed the same pull pot he used which are impossible to find so I used a 5K and made it 1 meg by switching out the disc from a regular vintage pot of the same. After this pic I added a three stage gain boost on the two added stages and a two way sat switch. I found mine too bass heavy with the 20uf cathode caps on the added two gain stages so I dropped those to 10uf after comparisons in mine. I did not care for the bass boost in the one I owned that had it and neither had his gate. Killer amp. They are bone stock JCM 800 with the pot disengaged as no other components are swapped at all. Only difference is now shielded leads. You have to keep the preamp knob low on these mods to keep it tight with the circuit engaged.
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Do you have any schematics of these mods that can be shared?
 
Shask said:
Do you have any schematics of these mods that can be shared?
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Its been awhile since I did it. I only cloned it and did it as I went so no schematic or layout. I am an awesome copycat lol plus I know enough to be dangerous. Been soldering and tinkering for 25 years
 
Soundstorm said:
So I'd just look for the two 20uF caps on the extension board and replace those? I know reports vary a bit on the low end response of these so I'm guessing he changed the circuit up a bit over the years
Soundstorm said:
So I'd just look for the two 20uF caps on the extension board and replace those? I know reports vary a bit on the low end response of these so I'm guessing he changed the circuit up a bit over the years
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If you look at my pic you can see the two yellow cathode caps. on the added tube.. I think he used a 1.2K cathode resistors across each one. You can see the color codes.
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I have a modded JMP Superlead and it’s pretty awesome sounding. It’s a little trickier to dial in than my 2203 but it kicks ass.

When the mod is engaged the volume 1 and 2 affect the sound, and there’s 2 knobs in the bottom inputs. The pulled knob works the the gain and I believe the other might work one of the preamp tubes.

The volume is nuts. 0 to earth shattering at a fraction of a turn.

Someone scratched in marks where to dial in the tones and it’s pretty on the money.
 
glip22 said:
One of my favorite mods. I owned two of them and cloned one into an 89 JCM800 with a few tweaks and its an awesome amp. They go from clean to mean with little volume drop because of where the circuit is placed after the stock gain stages before the cathode follower. I even constructed the same pull pot he used which are impossible to find so I used a 5K and made it 1 meg by switching out the disc from a regular vintage pot of the same. After this pic I added a three stage gain boost on the two added stages and a two way sat switch. I found mine too bass heavy with the 20uf cathode caps on the added two gain stages so I dropped those to 10uf after comparisons in mine. I did not care for the bass boost in the one I owned that had it and neither had his gate. Killer amp. They are bone stock JCM 800 with the pot disengaged as no other components are swapped at all. Only difference is now shielded leads. You have to keep the preamp knob low on these mods to keep it tight with the circuit engaged.
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Do you remember the coupling cap values? I've been searching for them everywhere. Is the film cap a 10n and the ceramic 2.2n or something close?
 
stinkfeet said:
Do you remember the coupling cap values? I've been searching for them everywhere. Is the film cap a 10n and the ceramic 2.2n or something close?
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All coupling caps are stock amp acceptthe two coming off of the added pretube.The 2 Yellow couplers are 10uf. They were 22uf. The blue cap I think is 1.1 or so
 
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