Interestingly, there is a video of EVH playing at a private party with 3 EVH half stacks behind him. Look closer and none of them are plugged in, but there is this JCM 900 on the floor that is plugged in and providing the sound!
you really should consider offering a retrofit board for a dsl/tsl jcm2000 head. There are tons of these amps out in the wild and marshall screwed up the PCB's on them so many need replacement. i have one that is hanging by a thread
I actually did a whole rebuild of my DSL that way. Replaced the pcb with two turret boards. One for the psu and one a for 2203 style circuit with a switchable gainboost. I designed a custom metal plate that replaces the old one and is a drop in replacement, no additional drilling required. So the whole amp could be returned to stock, if desired. Sadly the amp has a problematic 50 cycle hum caused by the magnetic field of the powerfransormer. I'm pretty sure the powertransformer is damaged, because the amp had been dropped in the past.
@@UncleBensRice well i am considering gutting the amp and retrofitting a Headfirst Cali board into it. This would require some drilling into the chassis in various spots to locate sockets and such. Would need a new faceplate as well. Looking at the internals of this amp does not exude confidence, lots of thin ribbon cables and such
I’ve got a jcm2000 sitting on a shelf that will one day be gutted for one of my boards. A Cali would fit it well without drilling out the faceplate. You’d need to put some new sheet metal in the top of the chassis for tube sockets though.
@@HeadfirstAmps That's exactly what I did. I removed the metal sheet on the top and every pcb board except for the small main pcb. I designed and lasercut a new metal sheet with eight holes for the tube sockets. That metal sheet screws right into the six old holes on the main chassis. No additional drilling required. I kept the faceplate stock. Small alpha pots and cliff/neutrik jacks will fit into the old holes. I can send pictures if you're interested.
I used a jcm 900 / 4500 on the road for 3 years it sounded great and was verry dependable with regular service I have several marshalls fromm 68 plxi's to jcm2000 100 w they all have something to offer I don't mod my amps I buy what I want to hear for a specific sound molded amps are difficult to fix on the road from my experience !
Hey Jason it's Lou ! Hope all is well ! Playing my JMP as always but someone is offering me a mint JCM'900 SLX and I was wondering if you sell some boards that would fit well with those amps ? Thanks
I just bought a marshall jcm900 mkiii 2100 and would like an advice from you or anyone here. What is , or makes a good EQ quality to put inside of the amp ? Thank you
Very cool and adventurous rebuild of a JCM900! I really appreciate the walkthrough at the end of the voltages in the amp. I have written down all the measurement nodes and voltages you checked to study. I am learning a lot from you and am grateful for your contributions to the guitar amp community. The amp now sounds terrific!!
Another awesome vid Jason! What coax do you use? Its hard to see. I just ordered some RG-174/U Coax as its all that seems to be easily available in short lengths here in UK, but not sure its going to be thick enough?
Hi, Jason. Thank you for detailing the plate voltages. Do you recall what the loaded heater voltage was? I have seen a couple of 900s recently with (to me) higher than expected voltage
I love stuff like this, learning what parts that make amps that the 'general populous' say are 'dog-crap' turn into a VERY versatile beast of an amp! I'd always heard that the JCM 900 was 'junk' compared to the JCM 800, but had my doubts about that. I could hear thier tonal differences, but always thought that you could 'customize' them if you knew what the initial problems were in the first place. I later learned that's what was meant when the term 'modded' was used. I can solder and wire guitar electronics, but would have to be WAY, WAY BETTER at it than I am currently before I'd feel confident to do what this guy & others like him are doing here! Thanks for putting this up Brotha! It inspires me, if I'd ever get my hands on a JCM 900 & decide to 'mod' the thing myself. And, if I'd screw it up, I'd just find someone who could do the mods and have it done.
Only reason I got this amp was for the “clean” channel. Shame the dirt channel don’t got the balls of the 800. Not saying the dirty channel bad. It’s just not an 800. And the rebuild sounds great.
Hi Jason, As always, sounding killer! My 2100 SL/X is untouched and sounds killer (all valve except for the loop, has 4 xax7's, no reverb). What model 900 was this? Dual reverb? I think the problem with the 900 is there are some good and not so good ones. But not a lot of advice regarding the different versions, and needs to be clarified.
Hey Chris, thanks. This was a 4100, the SL/X is all tube and I understand was a bit of a response to the reaction to the solid state preamp of the 4100.
@@HeadfirstAmps I've never tried the DR,, but pretty sure when I was 18, one of my mates got one and it sucked. SL/X/Mk4 is a funny circuit, starts off with a follower pair, which really is all that constitutes the extra AX7. Bit of circuit reading, worked out could put my Soldano Hotmod into P3 (not P2, as per "normal" Marshall, including the Mk3, which was all valve). It roars!
The SL/X is not bad but falls apart on the low strings when you get the gain up. It always seemed the MKIII’s and DR’s just had a sterile quality to them compared to a 2203/4. Makes a lot of sense to me that they’re not just a simple mod from glory.
I can't believe marshall is trying to get $2699 out of a JCM900 now days. I bought mine for $400 and sold it for $450. It's not a $2700 amp I'm sorry lol.
Nice rebuild. What capacitors (electrolytic) brand do you using on the PCB boards? Makes some difference put the first grid stopper resistor closest to the tube pin?
Putting diodes in front of the amp isn't "solid-stating" the preamp too? What about the Jubilee, isn't that solid state too? Why the 900 getting all the hate?
This is what the customer wanted. He wanted it gutted. I guess there is a difference too between using diodes for clipping and compression vs. using transistors for gain stages...
@@HeadfirstAmps I apologize if I sounded harsh, I’m a little drunk now, but it was a legit question of mine. I understand the difference between diodes and transistors, I just don’t know which amp uses what. Guess is google time…
I've got a '91 4100 with the diode bridge on ch B cut out and a 100k resistor in its place (google cathbard mod). This has made my 4100 much more of a beast on ch B. I would really like a push/pull pot to toggle in/out the fixed eq on ch B. I also own a Ceriatone Yeti - they very much sound like cousins with the 100k resistor mod.
@@wjbecker4 also, a jj ecc832 (half high gain, half low gain) tube in v1, which is the cathode follower and tone stack, really make this amp sound 'classic marshall'. cheers!
Now it doesn't sound like a JCM 900. If you were selling it the only way I'd give you anything is if you changed it back. I like the sound of my JCM 900.
