I’ve just done this mod to my 2203 and it sounds and feels absolutely superb!! For anyone thinking of doing it (if you know what you’re doing) do it!! Completely reversible, but guarantee you won’t change it back. Amp now sounds bigger, but the low end is tighter and the clarity is great. Doesn’t add a massive load of gain - Just enough IMHO. Great stuff!!
This is absolutely crystal clear. Love your patient and calm approach, walking through the circuit. I learned a lot - thanks! I'm also impressed with the clean way of adding components, without disturbing other existing ones. I do worry about modding my completely stock 1984 JCM 800....But this definitely makes it an option.
Just a note guys - at the 3:12 mark I mention 1987 & 1959 model Marshalls. They have the same PCB, but would require to be converted into 2204/2203 spec for this mod to then be applied...
Thanks so much for this Jason. Made the mods to my 1987x and now it sounds amazing. I removed the two unused jacks on the front panel used one for the depth pot and the other for a DPDT switch to make the 3k3 and .68uF across the 10k cathode resistor and the 220k across the gain pot switchable. In the up position it’s pretty much like a stock 800 with the cold clipper and in the down position you get the JEL mods in input 1 and a pretty convincing Plexi sound in the low input with the master on full. Thanks again!
hello, your modifications are certainly interesting, give us a video with the result of the change of sounds which if relevant, this will be more concrete for the audio of your modification thanks
Stumbled upon your videos couple a days ago; wow, really like how it's done and presented! And very generous too by sharing schematics 👏 I've done a slightly different take on the JEL; shifts upper-mid emphasis a bit lower in frequency and a bit less gain: 4n7 instead of 2n2 from 1st stage, 470k/470p can be left as is or both replaced by 220k (depending on wanting more/less highs), no 220k over gain-pot, 1nF on gain-pot changed to 120pF and a 680k from wiper to ground, 3k6 instead of 2k7 on 2nd cathode and no 0,68uF, 2n2 out from 2nd stage (important), and no 22uF on 3rd cathode. Keep 470pF over 100k on cathode follower. Can be worth trying 390pF as alternative value for 470pF in tone stack; gives a slightly different feel to the highs.
What's funny and to balance it out is like you said, the front end is tightened up going from the 22n to the 2n2. Also to mention, the gain pot has a 1n "bright" cap on it! BUT...the 470p on the 100k cathode Follower is Friedman's "Dark" MOD and darkens it. Likewise, as you said Jason, the 4 ohm tap will make the amp sound more "dark" and again rolling off the top end.
@@cap217cap217 On the early BE-100's, Dave Friedman used to label the amps "DARK" for Dark MOD. What it would do is on a switch add a 500pF Mica capacitor on top of the 100k cathode follower resistor.
How is this JEL100 spec when the 2203ish channel on that amp has a depth control and a switch with two gain levels? This sounds great but maybe it is it's own thing.
I did it to mine. I ended up with a motorboat and a steamwhistle. Took it all out. Probably did something wrong. But as I don't have an oscilloscope to find the problem I'll leave the amp "stock".
Amp tones are fantastic Jason! What is in your signal chain for this recordings. I am new to guitar recording software and hardware, so please if you can, describe it in details. Thank you!
Ahhh. 30 years ago I modded my jmp. 5 years later I unmodded it. 5 years later I modded it again. 5 years later I unmodded it. 5 years later I modded it again. 5 years later I unmodded it and have been happy with using a SD-1 until hearing this. After hearing this I’ll be dipped, I am probably going to try this mod. Is there a 12 step program for people like me?
Great videos thank you! I have a question, I plan to build a "clone" of a 2204 but with some mods. I want it with a power scaling similar to a Origin 20, do you have the squematic of a power scaling I can add to a 2204 ? And I want some simple and switchable mod to add more gain, I don't know if you have some recommendations..
I haven't yet traced out the Origin 20's power scaling, but I can tell you it's a cathode bias amp and the scaling is done via varying the screen voltage, and also the PI supply. Switchable boost, check out my FET boost board, perfect for a 2204. Watch my 1987x part 3 mod clip for details.
I have a question about your preference of the 0.68uF electrolytic over other capacitor types. Can you describe the sound difference you observed over other types? I don’t doubt there is a perceived difference. Is it more musical, less sterile, lower microphonic,? I understand this is an area that some will argue can’t affect the sound but electronic components are not ideal and some of the non ideal characteristics are desirable.
Sounds Gloriuos!...i own a BE100Dlx ( love that Black thing! )...i know you know your way on the Friedman Circuits...do you think i can get close to that circuit/sound with my amp?...not exactly maybe...but close would be great!....love your videos man!...now i want a 2204 to mod it!
Good work, nice playing as well. Nice of you to provide documentation. Any chance you could do a clip of the Low input with the master cranked and preamp volume at low levels for a plexi sound?
there's a massive difference in this mod between leaving the stock 100k nfb resistor and the 47k from the mod. I played with this and ended up with an 82k. A 47k and you just lose alotta life in the sound. i suggest folks test this before committing
Hi Jason, thank you very much for this extremely well explained sharing of information which made me want to get started! I did everything scrupulously but I have a small problem: as soon as the preamp is above 3, the sound, although not saturated, cuts off... and comes back if I drop below 3 When I put the 10k cathode resistor back on V1b as originally (instead of its recommendation: 4.7k + 0.68uf in parallel) the sound returns to normal. I also tried a value of 4.7 k instead of 10k the sound cuts out too... A small idea? 😀 Kisses from FRANCE
@@patwebb6534 Sorry for the late reply. I've gone as far as I can without finding it. I took my amp head to the technician. I'll get it back soon, I'll let you know... 😉
@Headfirst Amplification As I'm looking at the two mods. I see the parts that are the same, but coming off of V1 A in the JEL100 mod you have added a 3k3 resistor instead of replacing existing resistor like you did in the SC20H mod. what is the reason for that? Also on the JEL100 mod you have a 220K ohm resistor in the circuit, which you do not have on the SC20H mod. What is the purpose for that? Sorry for all the questions, but just trying to understand more about the circuits. I like the sound of the JEL100 mod better than the one done to the SC20H and am wondering if it is due to those changed mentioned above.
I didn't replace the'10k resistor because I wanted to make all the mods in my 2203 easily reversible. The 220k resistor over the gain pot? That just reduces the gain at that point in the circuit a little.
That amp sounds killer, I want to build a 800 replica, may be from Ceriatone or something like that, I wonder if some mods like this could be added with a switch so you can have your "stock 800" just with a switch. Is it posibble? may be just a mod that adds a bit more gain to avoid using a pedal. May be just the famous 22uF cap you mantioned. What you think?
@@HeadfirstAmps great, I think I will go for this, question: do I need a single switch for every single piece changed ? Can I use some modes separately or do I need to switch all together in order to work correctly?
Hey headfirst! RIPPING mods and playthrough done here. Burning questions I couldn't find the answer to are : I have a jcm800 2203 *reissue* headfirst I believe it is from 2016 1. Will these JEL mods still work? 2. Will these work IF I do the old trick to remove 2 power tubes because I've been wanting to take the amp from 100 watts down to 50 watts as I don't feel I really need the full 100 at home ? ^ Hope those make sense. Thanks mate and cheers from Niagara falls Canada! 🇨🇦🙏🏻🤟🏻 - Adam
Hello, I am going to need this schematic (mods not required) and this is the clearest Ive seen, i couldnt reach your webpage, I remember you have them there. How could I get that schematic in PDF??
Thanks! Yes, it certainly can as Marshall use the same ST1 board for both the 1959 & the 2203. You'd need make a couple of changes to how V1 is wired up to convert the plexi into a 2203 with cascading gain stages.
i tried this mod but to me its a bit of a one trick pony,it seems i can't control gain with the guitar volume,it's good if you only play all the time full crunch and add a boost for solos.Which is your favorite type of preamp for versatility,or going from quasi clean to 80s rock crunch?
Can this mod be applied to the SC20H studio classic Jcm800 variant? I know you have a video with a mod to it, but am only looking to add more gain, and this amp in this video sounds more like what I am trying to get from my Studio classic. Also on the video for the studio classic mod, what are the settings during the play thru?
@@HeadfirstAmps As I'm looking at the two mods. I see the parts that are the same, but coming off of V1 A in the JEL100 mod you have added a 3k3 resistor instead of replacing existing resistor like you did in the SC20H mod. what is the reason for that? Also on the JEL100 mod you have a 220K ohm resistor in the circuit, which you do not have on the SC20H mod. What is the purpose for that? Sorry for all the questions, but just trying to understand more about the circuits. I like the sound of the JEL100 mod better than the one done to the SC20H and am wondering if it is due to those changed mentioned above.
@@HeadfirstAmps yeah I thought about it but I'm really enjoying the stock. I think I still have one board and 2 sets of transformers for a 50 watt marshall. I want to do this with a custom faceplate from you
I understand this is a mod for Jake E Lee but, the 220k resistor across the Gain pot seems really excessive. I wonder if a 1M across the Gain pot would OK for retaining gain and not causing any blocking distortion? What am I missing? Great video! Just discovered your channel.
Thanks for watching. Yeah, you can absolutely tune this to taste. I've modded with none, 1M and 220k and always do it based on how the amp is sounding. They are not always the same, so this is one spot where you can tune to taste.
If you do nothing else to a stock 2203 except add the 220k//.0047 NFB off the 8ohm tap (to keep the stock 100k resistor vs swapping to a 47k) what happens to the sound?
Thank you for sharing this Jason. Quick question. I’ve got the mod in, but when I add the 3k3 and .68 cap cold clipper it is not working properly. Sounds like bad oscillation high pitch etc.. i have it on alligator clips and if I take it out it works fine. Any ideas?
Thanks for the reply. Ok I tried that as well and still isn’t working, I’m kinda stumped. It’s really broken up sounding like barely any output and fuzzy. Another symptom I’m having is when the gain pot is all the way up it is also cutting out with out the 3k3 and .68 and 220k across the gain pot jel low gain set up. Any help is appreciated. I don’t think this amp has grid stoppers. It’s a 78 jmp 2104
@@HeadfirstAmps would that be one of the blue wires coming off of v1? It’s the same board as in your video, just the caps are the older variety not the red bricks.
There was a 100pf cap soldered to the v1 tube socket, I had removed while troubleshooting the amp. Perhaps that was intended as C2? I believe it was pins 7 to 9.
My amp purple and black wires are connected together in the impedance selector. Do I still put the cap and resistor only in purple wire ? And connect the black in the same lug? My cab is 8 ohm... Thanks!
I tried this on my amp and it’s extremely noisy. My amp hisses and squeals and once you go above 6 on the gain it loses control completely. I was wondering if you heat shrink the leads, and try to separate the caps (bright cap and treble peak) off the preamp volume pot to get rid of this? When I touch or wiggle the cap/resistor on my gain pot the amp goes into full on broken up fuzz or just squeals like I’ve got a gremlin inside of the speaker cab. How do I get this thing working normally ?
Sounds like you’ve got something not wired correctly, or a bad connection, missing ground even. Join my FB DIY Builders group and post some pics there.
@@HeadfirstAmps ok I’ll do that. I’ve gone over the wiring diagram and schematics a few times, and re-soldered the wiring on the pot a couple times now, still no success. I’ll take a few pics and see what I can learn from what went wrong
If you just change the 100k NFB to 47k, what happens with no other changes? I have a super lead that I want to make a little more punch, umph, and way less brightness. I dont want to remove the resistor. How can I lower it to 47k? I see I can just piggyback another 100k to make it 50k. What will happen>
By lowering that 100k to 47k you will increase the NFB, making the amp a little darker and tighter. The other way to do that without having to change any resistor is to move the NFB up one on the impedance switch. I.e from 4 to 8 ohms, or from 8 to 16.
@@HeadfirstAmps My NFB Purple wire is connected to the output jack wire that goes across and connects them. The one towards the board. I assume this is getting the tap off whatever ohm you select. I play 16 ohm cabs and its bright. Bright meaning I am turning presence and treble off, on 0.
@@HeadfirstAmps so if I wanted the negative feedback on a “Depth”knob,would you put the pot wired into the boards negative FB resistor,or wire it into the impedance Jack?...also,if the NFB comes from the 4 ohm tap,does that mean you get more or less NFB if you are using say the 16 ohm setting to match your cab??
@@scottpeters4401 Hi Scott, two things. Variable negative feedback and depth are different, but related. I wire from the impedance selector to depth (with fixed or variable resistor), to NFB resistor (fixed or variable). You can put none, one of or both of these controls on pots. 4 ohm tap gives you less, 16ohm tap more NFB.
I did this mod to my 2203 and I left the 100k negative feedback resistor.... its kinda throwing glass at me and oscillating a little....I'm going to try a 100k resistor in parallel and see if its any better... otherwise I may go back to stock.
@@HeadfirstAmps I placed the 100k in parallel with the stock feedback resistor per the schematic and WOW...... that piece was key. It sounds so much better its unreal.. just goes to show mods are a recipe,, you have to get every detail right or it will be off. Posting this for others who intend to try this for themselves..... its a great mod!
@@HeadfirstAmpsthanks for the reply! I realized that now after watching this video 10 times. I guess I am a little slow in the uptake! I am going to search for a different mod to keep the 1987 circuit but try to tighten it up a bit. I just finished this build and it’s for a friend as a gift. Pretty much stock 1987 with a LarMar PPIMV. I am just getting ready to test voltages. Looks like my next build is gonna have to be this! Thank you so much for all of your insight. You are extremely easy to follow and your teaching here is exactly my learning style. So, thanks again!!!
Could it be possible to put this mod behind the switch so you can switch between Jake E. Lee Mod and original? Sorry I'm not very familiar with electrics. Thank you so much for the videos! Edit: Found the answer below. You're talking about this one? ua-cam.com/video/7ueoF1UPrHQ/v-deo.html
I’ve just done this mod to my 2203 and it sounds and feels absolutely superb!! For anyone thinking of doing it (if you know what you’re doing) do it!! Completely reversible, but guarantee you won’t change it back. Amp now sounds bigger, but the low end is tighter and the clarity is great. Doesn’t add a massive load of gain - Just enough IMHO. Great stuff!!
did you leave the NFB resistor at 100k or did you change it to 47k?
This is absolutely crystal clear. Love your patient and calm approach, walking through the circuit. I learned a lot - thanks! I'm also impressed with the clean way of adding components, without disturbing other existing ones. I do worry about modding my completely stock 1984 JCM 800....But this definitely makes it an option.
This rips mate, best tone I've heard on your channel so far
Wow, tnx man!
These vids are really well done right down to the great playing and sound demos. Thank you very much.
Thank you kindly!
I like your videos and the mods to modern Marshall amplifiers. Defintely improvements compared to other mod videos that I've watched. Cheers!
Cool, thanks!
Just a note guys - at the 3:12 mark I mention 1987 & 1959 model Marshalls. They have the same PCB, but would require to be converted into 2204/2203 spec for this mod to then be applied...
Can this be done to original vintage 1987/1959s?
Any similar sounding mods for 1987 circuit with a LarMar PPIMV already installed?
EXCELLENT CRYSTAL CLEAR VIDEO! 👍
Thanks so much for this Jason. Made the mods to my 1987x and now it sounds amazing. I removed the two unused jacks on the front panel used one for the depth pot and the other for a DPDT switch to make the 3k3 and .68uF across the 10k cathode resistor and the 220k across the gain pot switchable. In the up position it’s pretty much like a stock 800 with the cold clipper and in the down position you get the JEL mods in input 1 and a pretty convincing Plexi sound in the low input with the master on full. Thanks again!
hello, your modifications are certainly interesting, give us a video with the result of the change of sounds which if relevant, this will be more concrete for the audio of your modification thanks
Great content. Looking forward in getting one of your boards. Just reading up stuff to make sure i dont shock myself to death
Ha, yes indeed.
Absolutely outstanding !!!! - Thanks for sharing Jason -
Great videos. Thank you for such great content, explanations and products (first order placed, more to come).
Awesome! Let us know how the build goes.
Thank u for this guide, man. When you make a Splawn Quickrod board, i'll sure buy ate least two for me.
I just tried your Cali 50 Kemper tones and they are sick 80's tones. Thank you for making them
Glad you like them!
Stumbled upon your videos couple a days ago; wow, really like how it's done and presented! And very generous too by sharing schematics 👏
I've done a slightly different take on the JEL; shifts upper-mid emphasis a bit lower in frequency and a bit less gain: 4n7 instead of 2n2 from 1st stage, 470k/470p can be left as is or both replaced by 220k (depending on wanting more/less highs), no 220k over gain-pot, 1nF on gain-pot changed to 120pF and a 680k from wiper to ground, 3k6 instead of 2k7 on 2nd cathode and no 0,68uF, 2n2 out from 2nd stage (important), and no 22uF on 3rd cathode. Keep 470pF over 100k on cathode follower. Can be worth trying 390pF as alternative value for 470pF in tone stack; gives a slightly different feel to the highs.
Good ideas. I like 390pF a lot here or there.
Great !,.....just stumbled on your channel because of someone mentioning it on the Marshall Forum so I just subscribed !
Awesome! Welcome!
Great description of negative feedback in part II of the video. Time to fire up the soldering iron!
Awesome! Thanks for another project. My free time is now consumed lol!!
Let us know how you go with the mod!
Playing is 🔥 today mate. Sounds great as always.
Thanks man!
Sounds very nice!! Another very informative video. Thank you.
Thanks for watching!
Thanks for sharing! I know what I’m doing this evening!!
Ha, awesome. Do it!
@@HeadfirstAmps Well between jobs and life getting in the way, its done: ua-cam.com/video/1DmKWL2XyqQ/v-deo.html
What's funny and to balance it out is like you said, the front end is tightened up going from the 22n to the 2n2. Also to mention, the gain pot has a 1n "bright" cap on it! BUT...the 470p on the 100k cathode Follower is Friedman's "Dark" MOD and darkens it. Likewise, as you said Jason, the 4 ohm tap will make the amp sound more "dark" and again rolling off the top end.
What do you mean "dark" mod? What amp has this? I thought he used a 1000pf here in the be.
@@cap217cap217 On the early BE-100's, Dave Friedman used to label the amps "DARK" for Dark MOD. What it would do is on a switch add a 500pF Mica capacitor on top of the 100k cathode follower resistor.
Wow! Very nice of you! Sounds great!
Glad you like it!
Great playing ! With attitude and passion.
Thanks!
How is this JEL100 spec when the 2203ish channel on that amp has a depth control and a switch with two gain levels? This sounds great but maybe it is it's own thing.
Well, it’s essentially hard wired in the higher gain position and has a fixed depth (like having the depth pot at midday give or take)
Dude that sounds absolute filthy, RNR !!!!!! Superb vid's
That’s it???
That’s what the Friedman Jake E Lee amp is basically?
Great videos man. Hats off
Great Video! Totally enjoyed it.
Glad you enjoyed it!
I think I need to do this to my Ceriatone 2204 ASAP haha
I did it to mine. I ended up with a motorboat and a steamwhistle. Took it all out. Probably did something wrong. But as I don't have an oscilloscope to find the problem I'll leave the amp "stock".
Excellent tutorial!
Thank you! Cheers!
brilliant my man this is invaluable
Amp tones are fantastic Jason! What is in your signal chain for this recordings. I am new to guitar recording software and hardware, so please if you can, describe it in details. Thank you!
I am not really into the high distortion thing, I like the semi clean Hendrix stuff, but I really enjoy your videos, so thanks a lot.
@headfirstamplification this video is amazing! For the 0.68uf and 22uf caps can you substitute mojo dijons or similar for the caps you used?
Sounds amazing.
Uh you’re an amazing amp tech wholly
Ahhh. 30 years ago I modded my jmp. 5 years later I unmodded it. 5 years later I modded it again. 5 years later I unmodded it. 5 years later I modded it again. 5 years later I unmodded it and have been happy with using a SD-1 until hearing this. After hearing this I’ll be dipped, I am probably going to try this mod. Is there a 12 step program for people like me?
Sounds like you already did the first 6 steps. 😂
That sounded Killer. Nice hard Tail. Can JEL mod work w the 34 and 36 mod all in one amp?
still trying to find the parts list and if it is sold on your website please post the link awesome sound
So I've been running a hot mod evo 2 in my 77 2204. Aside from the extra gain stage is there much difference in the low end cut and response?
Great videos thank you!
I have a question, I plan to build a "clone" of a 2204 but with some mods.
I want it with a power scaling similar to a Origin 20, do you have the squematic of a power scaling I can add to a 2204 ?
And I want some simple and switchable mod to add more gain, I don't know if you have some recommendations..
I haven't yet traced out the Origin 20's power scaling, but I can tell you it's a cathode bias amp and the scaling is done via varying the screen voltage, and also the PI supply.
Switchable boost, check out my FET boost board, perfect for a 2204. Watch my 1987x part 3 mod clip for details.
@@HeadfirstAmps That power scaling is something that any technician could make?
Hmmm, no probably not 'any'
I have a question about your preference of the 0.68uF electrolytic over other capacitor types. Can you describe the sound difference you observed over other types? I don’t doubt there is a perceived difference. Is it more musical, less sterile, lower microphonic,? I understand this is an area that some will argue can’t affect the sound but electronic components are not ideal and some of the non ideal characteristics are desirable.
I’d love to have the answer as well
Sounds Gloriuos!...i own a BE100Dlx ( love that Black thing! )...i know you know your way on the Friedman Circuits...do you think i can get close to that circuit/sound with my amp?...not exactly maybe...but close would be great!....love your videos man!...now i want a 2204 to mod it!
Good work, nice playing as well. Nice of you to provide documentation. Any chance you could do a clip of the Low input with the master cranked and preamp volume at low levels for a plexi sound?
Yes sure, I might feature the amp again soon so stay tuned.
Thank you for sharing
My pleasure
Also, the 470pf over the 100k. Does the 500pf off the cathode stay? What is that capacitor right up against the green 470p you added?
Beautiful !❤
Jason, what exactly does the 220k resistor achieve across the gain pot? Thanks
How about the 2205/2210 any tasty mods to boost the less desired
Can you compare this to the Friedman Jake E Lee amp?
Does it sound the same?
This sounds more Marshall from videos I’ve seen on the Jake amp
s-u-p-e-r interesting and very well explained! thanks so much for sharing this, love it!
there's a massive difference in this mod between leaving the stock 100k nfb resistor and the 47k from the mod. I played with this and ended up with an 82k. A 47k and you just lose alotta life in the sound. i suggest folks test this before committing
24:00 why choosing an electrolytic cap instead of a ceramic? and didn't the schematic say to use 400v? I'm new to this kind of stuff and I'm confused.
So If I don't put the 220K resistor in parallel the preamp volume will oscillate? I have to experiment some more but figured I would ask
Maybe, maybe not. It depends..!
Hi Jason, thank you very much for this extremely well explained sharing of information which made me want to get started!
I did everything scrupulously but I have a small problem:
as soon as the preamp is above 3, the sound, although not saturated, cuts off... and comes back if I drop below 3
When I put the 10k cathode resistor back on V1b as originally (instead of its recommendation: 4.7k + 0.68uf in parallel) the sound returns to normal.
I also tried a value of 4.7 k instead of 10k the sound cuts out too...
A small idea? 😀
Kisses from FRANCE
I have the same problem. Did you ever figure out what the issue was?
@@patwebb6534 Sorry for the late reply. I've gone as far as I can without finding it. I took my amp head to the technician. I'll get it back soon, I'll let you know... 😉
@Headfirst Amplification As I'm looking at the two mods. I see the parts that are the same, but coming off of V1 A in the JEL100 mod you have added a 3k3 resistor instead of replacing existing resistor like you did in the SC20H mod. what is the reason for that? Also on the JEL100 mod you have a 220K ohm resistor in the circuit, which you do not have on the SC20H mod. What is the purpose for that? Sorry for all the questions, but just trying to understand more about the circuits. I like the sound of the JEL100 mod better than the one done to the SC20H and am wondering if it is due to those changed mentioned above.
I didn't replace the'10k resistor because I wanted to make all the mods in my 2203 easily reversible. The 220k resistor over the gain pot? That just reduces the gain at that point in the circuit a little.
That amp sounds killer, I want to build a 800 replica, may be from Ceriatone or something like that, I wonder if some mods like this could be added with a switch so you can have your "stock 800" just with a switch. Is it posibble? may be just a mod that adds a bit more gain to avoid using a pedal. May be just the famous 22uF cap you mantioned. What you think?
Yes, all the mods can be made switchable. If you check out Rubber Duck Tech's channel, he did exactly that.
@@HeadfirstAmps great, I think I will go for this, question: do I need a single switch for every single piece changed ? Can I use some modes separately or do I need to switch all together in order to work correctly?
Hey headfirst! RIPPING mods and playthrough done here. Burning questions I couldn't find the answer to are :
I have a jcm800 2203 *reissue* headfirst I believe it is from 2016
1. Will these JEL mods still work?
2. Will these work IF I do the old trick to remove 2 power tubes because I've been wanting to take the amp from 100 watts down to 50 watts as I don't feel I really need the full 100 at home ?
^
Hope those make sense.
Thanks mate and cheers from Niagara falls Canada! 🇨🇦🙏🏻🤟🏻
- Adam
1. Yes absolutely perfect starting point
2. Sure, just remember to move the impedance selector down one notch. E.g. for 16ohm cab, set amp to 8.
Is the low input still usable (sound wise) with this mod? Is it plexi-like?
Oh yeah absolutely. Just like an unmodded JMP or JCM800's low input, only a bit fatter and fuller.
hello, you change the bias resistance to reach 50 Kohms but how much do you set the bias?? 30 ?? 35mA??? Thank you for your reply
continue thank you
Can the cold clipper mod be made as footswitchable (hot to stock) ?
You can footswitch it via a relay, but you do have the issue of the loud pop that occurs when you change the cathode resistor value.
Sounds great mate. I assume i could get this done to my 83 JCM800 4010 combo (2204)?.
Yep, it's a 2204 circuit so absolutely could be done.
@@HeadfirstAmps Great thanks for the quick reply cheers
Hello, I am going to need this schematic (mods not required) and this is the clearest Ive seen, i couldnt reach your webpage, I remember you have them there. How could I get that schematic in PDF??
mhuss.com/MyJCM/JCM800_2204.pdf
Killer tone! It’s says 2204/2203 but can this be done to a 4 hole Superlead? I know the circuits are pretty similar.
Thanks! Yes, it certainly can as Marshall use the same ST1 board for both the 1959 & the 2203. You'd need make a couple of changes to how V1 is wired up to convert the plexi into a 2203 with cascading gain stages.
@@HeadfirstAmps sweet thanks for the info mate! Can’t wait to have my tech do this mod!
Thank you for schooling us Jason! Are these mods doable on the horizontal input 2204?
Absolutely yes!
Only The Early JCM 800's were great then they went muck ? Eddie would buy that from you 💫
i tried this mod but to me its a bit of a one trick pony,it seems i can't control gain with the guitar volume,it's good if you only play all the time full crunch and add a boost for solos.Which is your favorite type of preamp for versatility,or going from quasi clean to 80s rock crunch?
I like this setup. If it's too much gain for you, try removing the 0.68uF bypass cap on the 2nd cathode. Or remove your bright cap.
How similar are these to the sir mods with the exception of adding gain stages? Stuff like the plate snubber look similar to the 36
Quite similar. The Bypass cap over the 10k cathode cold clipper is a bit part of the sound.
Can this mod be applied to the SC20H studio classic Jcm800 variant? I know you have a video with a mod to it, but am only looking to add more gain, and this amp in this video sounds more like what I am trying to get from my Studio classic. Also on the video for the studio classic mod, what are the settings during the play thru?
Sure, just do the circuit mods and leave out the José style zener diodes. I think I mention the amp settings in the video?
@@HeadfirstAmps As I'm looking at the two mods. I see the parts that are the same, but coming off of V1 A in the JEL100 mod you have added a 3k3 resistor instead of replacing existing resistor like you did in the SC20H mod. what is the reason for that? Also on the JEL100 mod you have a 220K ohm resistor in the circuit, which you do not have on the SC20H mod. What is the purpose for that? Sorry for all the questions, but just trying to understand more about the circuits. I like the sound of the JEL100 mod better than the one done to the SC20H and am wondering if it is due to those changed mentioned above.
I'm redoing my plexi after the Cali is fixed. Then I think I'm going to give this a go.
You could implement these mods on the 2204 board you have from us, no sweat.
@@HeadfirstAmps yeah I thought about it but I'm really enjoying the stock. I think I still have one board and 2 sets of transformers for a 50 watt marshall. I want to do this with a custom faceplate from you
@@HeadfirstAmps Im out of 1 watt 220k. would a half watt work here or should I use a 2 watt or just wait until my 220k arrives?
Awesome. More is more!
220k 1/2w would be ok over the gain pot. You'd want 1 watt (or 2w) for the depth circuit.
Id love to have the schematic or link to, for my 1978 jmp 50 mk2, thanks.
Will this MOD also be applicable to the Marshall SC20H Studio Classic JCM 800 Lead Series 20/5-watt Tube Head?
You'd need to convert the 4 hole plexi to a 2203/2204 cascaded preamp setup, and then the 5 or so 'hot rod' mods can be added.
14:45 are you sure you can go up to 470uf on this cap? that is awfully large.
It's not necessary, but you can. 220uF & 330uF are more common.
I understand this is a mod for Jake E Lee but, the 220k resistor across the Gain pot seems really excessive. I wonder if a 1M across the Gain pot would OK for retaining gain and not causing any blocking distortion? What am I missing? Great video! Just discovered your channel.
Thanks for watching. Yeah, you can absolutely tune this to taste. I've modded with none, 1M and 220k and always do it based on how the amp is sounding. They are not always the same, so this is one spot where you can tune to taste.
If you do nothing else to a stock 2203 except add the 220k//.0047 NFB off the 8ohm tap (to keep the stock 100k resistor vs swapping to a 47k) what happens to the sound?
You'll be adding low end thumo/depth
Thank you for sharing this Jason. Quick question. I’ve got the mod in, but when I add the 3k3 and .68 cap cold clipper it is not working properly. Sounds like bad oscillation high pitch etc.. i have it on alligator clips and if I take it out it works fine. Any ideas?
Solder it in with short leads as possible. The oscillation will be coming from your long unshielded alligator leads.
Thanks for the reply. Ok I tried that as well and still isn’t working, I’m kinda stumped. It’s really broken up sounding like barely any output and fuzzy. Another symptom I’m having is when the gain pot is all the way up it is also cutting out with out the 3k3 and .68 and 220k across the gain pot jel low gain set up. Any help is appreciated. I don’t think this amp has grid stoppers. It’s a 78 jmp 2104
@@HeadfirstAmps does this sound like an oscillation problem?
You described it as oscillation, so I agree
I was wondering if c2 is that first red block to the left? Looking to work a sir 34 mod on my JMP 2204. Are you using 1/4 watt resistors or 1/2 watt?
Possibly, you just need to trace the plate wire (blue) to see the coupling cap that is wired to each tried.
I normally use 1w, 1/2 minimum.
@@HeadfirstAmps would that be one of the blue wires coming off of v1? It’s the same board as in your video, just the caps are the older variety not the red bricks.
There was a 100pf cap soldered to the v1 tube socket, I had removed while troubleshooting the amp. Perhaps that was intended as C2? I believe it was pins 7 to 9.
The link doesn't want to open...
My amp purple and black wires are connected together in the impedance selector. Do I still put the cap and resistor only in purple wire ? And connect the black in the same lug? My cab is 8 ohm... Thanks!
Put the cap and resistor exactly where the purple wire that leads back to the PCB was connected to.
I suppose this could be done to a sc20h just the same ?
Yes, I have two other clips that show exactly this.
Does this clean up well with the guitar volume knob if the gain is maxed out?
Not too bad, similar to a 2203
@@HeadfirstAmps wow dude that's practically the perfect amp then
So you kept the 100k nfb. Did you also try with 47k like in jel friedman?
I think I moved the tap to the 8ohm, which would be the same as 4 ohm w/ 47k
I tried this on my amp and it’s extremely noisy. My amp hisses and squeals and once you go above 6 on the gain it loses control completely. I was wondering if you heat shrink the leads, and try to separate the caps (bright cap and treble peak) off the preamp volume pot to get rid of this? When I touch or wiggle the cap/resistor on my gain pot the amp goes into full on broken up fuzz or just squeals like I’ve got a gremlin inside of the speaker cab. How do I get this thing working normally ?
Sounds like you’ve got something not wired correctly, or a bad connection, missing ground even. Join my FB DIY Builders group and post some pics there.
@@HeadfirstAmps ok I’ll do that. I’ve gone over the wiring diagram and schematics a few times, and re-soldered the wiring on the pot a couple times now, still no success. I’ll take a few pics and see what I can learn from what went wrong
@@tysonmitchell1147 Did you ever fix this? What was the issue?
what would it sound like with 6L6 power tubes instead of EL34s???????? really would love to hear some Marshalls modded that way.
Isnt that how zakk wylde runs his jcm800s?
If you just change the 100k NFB to 47k, what happens with no other changes? I have a super lead that I want to make a little more punch, umph, and way less brightness. I dont want to remove the resistor. How can I lower it to 47k? I see I can just piggyback another 100k to make it 50k. What will happen>
By lowering that 100k to 47k you will increase the NFB, making the amp a little darker and tighter. The other way to do that without having to change any resistor is to move the NFB up one on the impedance switch. I.e from 4 to 8 ohms, or from 8 to 16.
@@HeadfirstAmps My NFB Purple wire is connected to the output jack wire that goes across and connects them. The one towards the board. I assume this is getting the tap off whatever ohm you select. I play 16 ohm cabs and its bright. Bright meaning I am turning presence and treble off, on 0.
I think I’m gonna do this on my 2203X.
Are you plugged straight in , No, pedals ? On the high Input ?
No pedals. Never any pedals with my amp demos, always just plugged straight in. Yes, High input.
Well I know what I'll be doing to my Metro clone first \o/
Out've curiosity what was the second mod edd had supposedly?
A 50k mid pot, rather than the stock 25k.
Did it compress like that in real life with real speakers on the single note flurry !?
Sure, if you’re prepared to run it loud.
Mod a 1987x 50watt to a Jose Mod with zener diodes for the next content plss
I've got a 1959SLP coming in for some treatment, let's see where it goes!
So is this mod max gain on channel 2 of the Friedman JEL??....I noticed the Friedman has a gain switch on channel 2...
Yes, max gain mode. You can implement min gain via leaving the 10k 2nd cathode untouched, and not putting the 220k resistor on the gain pot.
@@HeadfirstAmps That’s amazing that a handful of resistors and caps make that much difference....
The 2203/2204 is a classic circuit. An awesome platform to tweak from.
@@HeadfirstAmps so if I wanted the negative feedback on a “Depth”knob,would you put the pot wired into the boards negative FB resistor,or wire it into the impedance Jack?...also,if the NFB comes from the 4 ohm tap,does that mean you get more or less NFB if you are using say the 16 ohm setting to match your cab??
@@scottpeters4401 Hi Scott, two things. Variable negative feedback and depth are different, but related. I wire from the impedance selector to depth (with fixed or variable resistor), to NFB resistor (fixed or variable). You can put none, one of or both of these controls on pots. 4 ohm tap gives you less, 16ohm tap more NFB.
This work with the Studio Classic?
Yes
Any issues trying this on a SC20?
Perfect candidate.
Can I implement these mods on an sc20?
Yes you can, in fact I have two videos showing this and the SIR #34 mod for SC20's
I did this mod to my 2203 and I left the 100k negative feedback resistor.... its kinda throwing glass at me and oscillating a little....I'm going to try a 100k resistor in parallel and see if its any better... otherwise I may go back to stock.
Have you got the 470pF in over the 100k cathode resistor (v2b)
@@HeadfirstAmps Yes, its in... its a silver mica 470pf
Increase the NFB as you suggest. Also, make sure you have that 220k resistor across the gain pot.
@@HeadfirstAmps will do.... thanks again Jason
@@HeadfirstAmps I placed the 100k in parallel with the stock feedback resistor per the schematic and WOW...... that piece was key. It sounds so much better its unreal.. just goes to show mods are a recipe,, you have to get every detail right or it will be off. Posting this for others who intend to try this for themselves..... its a great mod!
Killer
Thanks man!
Does this work with a 50 watt 1987 circuit?
Never mind I missed the part where you said 1987x. Should be the same as my clone I built
You have to rewire the front end as a 2204
@@HeadfirstAmpsthanks for the reply! I realized that now after watching this video 10 times. I guess I am a little slow in the uptake!
I am going to search for a different mod to keep the 1987 circuit but try to tighten it up a bit. I just finished this build and it’s for a friend as a gift. Pretty much stock 1987 with a LarMar PPIMV. I am just getting ready to test voltages.
Looks like my next build is gonna have to be this! Thank you so much for all of your insight. You are extremely easy to follow and your teaching here is exactly my learning style. So, thanks again!!!
@@tfrost33elkhunter
So I received this gift yesterday, and it’s AMAZING! 🤘🏻🤘🏻🤘🏻
Could it be possible to put this mod behind the switch so you can switch between Jake E. Lee Mod and original? Sorry I'm not very familiar with electrics. Thank you so much for the videos!
Edit: Found the answer below. You're talking about this one?
ua-cam.com/video/7ueoF1UPrHQ/v-deo.html
Hi , I've done the mod and asked you a question on Marshal Amp Forum , if you ever get a chance , could you take a look please ? Regards!
Sure, I just had a look. I need more, detailed pics of the entire amp to help you man.
@@HeadfirstAmps Ok , thank you , I will open it up tomorrow and post some pictures , really appreciate it ! Lou
You can email me direct as well mate, no problem. Headfirst.amplification@gmail.com
@@HeadfirstAmps Sounds good , I'll email you direct ! Again , thanks !
@@HeadfirstAmps Good day, I've sent you the pictures so just wanna make sure they didn't end up in your spam mail
Damn bro get down