Those tone comparison clips are excellent. They really show the difference. Yeah the early circuit is brighter with more harmonics. And more crunchy. It's definitely better sounding. Good video!
Those horizontal input 800’s a great example of cost cutting gone wrong. Like Fender in the CBS era. But!! As you’ve pointed out, once fettled a little, absolute monsters. When I saw Zak with Pride and Glory you’ll notice all he seemed to use was horizontal in put 800’s (no doubt they were modded, probably Lee Jackson) Definitely something about them. Don’t get rid of it mate 😉
It's called the hot shield. Supposedly it decreases noise, I've also heard that it gives a cocked wah type sound not sure about that, but I've also read that on later models they just used the 100pf cap to cut parasitic interference. Idk how true any of this is, but yeah the hot shield I've read a lot about . I actually liked the later 86 sound it sounded clearer, with more headroom and the high end wasn't so raspy. I actually did a search in TH-cam looking to see if I could find a higher voltage 2204, but with a 20k preamp dropping resistor going towards the preamp. My idea was to try to keep the power section cleaner for more headroom, but drop it back down for the preamp. Nice amp and tones you have there, nice work also ☺️
Another great vid and incredibly informative! I bought a 100w one of these new when I was 17 (and yes I ran an SD-1 with it too). It was a great reliable amp but the amp gain always sounded a bit flat and listening to this vid just took me straight back there. I ran a Soldano Hot Mod for a bit which was cool (if not a bit noisy), and then I got a Soldano SP77 and had the amp modded to bypass the preamp - that combination absolutely kicked ass. The early 80's version mod really brought it to life and I can now understand why people chase after the JCM800's now.
Actually the horizontal input 100w 800’s are different again, they have less filter caps in than the earlier amps and are the most aggressive sounding 800’s of all. I think the metal players chase those versions. Check out Euge Valovirtas channel. He explains and demos the difference.
@@vintagesound8112in which way "more aggressive"? I have one and I confirm it drives me mad for how stiff, harsh and bright it is. Euge Valovirta's 800 are modded.
Great information and comparison. I never owned a jcm but when I come across one of these it’s good to have this info. I’m stuck with 3 JMP amps for now 😄
Im not sure if it is due to lower voltage in the phase invertor (allowing less muddy low mids or something) or reworking the shielded inputs for less parasitic capacitance bleeding the highs, but there's a dramatic difference in clarity with the early 80s recepie. It's pretty astounding, actually
Great video! Thank you so much for breaking this down in such detail. Much more than I could absorb but I get the idea. I doubt I would ever be ambitious enough to take on that mod but I'm knocked out that you are an amazing tech, know how to get great tone and you are a good player too! I have 3 early 80's vertical input 2204 amps and I will probably take them to my grave. Nothing beats the sound. Please tell me what speakers are you using and how were you recording the audio from the speakers?
Late 80s sounds like ass, dark, and like a blanket over it!! Easy enough to fix, which you did! :) I have a late-80s coming in this week, so will be fixing the B+ issue among other things.
My 2204 is a vertical input from '85. It probably my best sounding Marshall. And I have two 70's Jmp's. It's a difference playing at home or in a band. There is a reason Marshall did what they did.
I first heard about the shielded cable going to earth from Gerard Weber, he claimed it stops high freq oscillation, for a laugh I tried it on the input of my amp and it sounded duller. I have seen it implemented in Trainwreck amps on the wiper of the tone controls return stage and it has an 820 ohm in the valve socket and the cable is mounted to the other side of the 820 ohm. That works fine.
This is one of the few 1986 models I’ve seen where the cloth hasn’t turned fawn brown. My first 800 was an 86 with that feature and I’ve had a soft spot for 86 models in particular ever since.
I have a 1986 2204s classic limited edition small box, totally stock .and it sounds like the vertical input model .nowhere near as dark as this horizontal one sounds. The last thing I would want is to make it sound any brighter.
That is absolutely astonishing how different it sounded before and after. I've always heard the stories of how the horizontal inputs sounded bad but this really showed off in comparison the real difference. My 2204 is from '81 so for all intents and purposes it's a JCM800 version of the old Rose Morris era 70's amp with different cosmetics. Why do you think Marshall made changes for the worse tone-wise? I get the cost-saving measures of the all-on-the-board, but why change the circuit to sound "less good"?
The 2203 changes were definitely to same money, as they stripped out the 1/2 the filter caps. For the 2204's....hard to say why, but the higher voltages through the pre amp definitely make them very "strident".
@@HeadfirstAmps Very interesting. I guess cost-cutting took precedence over tone. To me, the early JCM 800's were the last of the great, classic Marshalls.
The shield connected to the plate is a way to incorporate the cable capacitance as negative feedback at high frequencies. I have heard about this being done in amps but haven't come across it before either. I think they said Mesa used to occasionally do this when hand wired? It is a way to drastically reduce gain at high frequencies. I don't recommend it.
Great video, I wonder if the 800 schematic in Headfirst web page (The one you can download in gif I think) has the correct voltages I should aim? I am about to build another 800 and I want to be sure to follow the ultimate JCM800 schematic. Id appreciate your help !
The anomaly of the reversed shield ground of input to V1 grid and anode existed I a few of the year 1983/1984 model 2204’s I encountered. Shock hazard but stock believe it or not. I have never encountered it though in a horizontal input so this may have been a poor decision of an individual mod following Marshall’s anomaly. David Hopkins
I liked the video and the initial comparison, but you said you were going to run the same clips through at the end. Instead you changed guitars and played very different notes. I don't have the comparison so I am not completely convinced. It is a nice technical presentation of the schematic differences in the two amps. And you showed the voltage changes.
You are saying the comparison was edited into the beginning of the video. That is an amazing difference. I'm curious are the transformers the same? 1202-324 pt, 784-139 ot, 1471-263 choke.
So glad I did the work to put it to 80's spec, and that 'hot shield' coax clearly was impacting the tone. I learnt that this era of amp needs to be thoroughly checked over, as most will have been modded to some degree.
I have my 2203 (86') I got it as that was my dream amp. It sound so muddy! One of my worst amps. This video probably save me some cash to replace it for youngest model! Could you let me know if i can base on your video modding my 2203? I see it's not different on diagrams, hence my question. Thanks a lot!
There is also another difference, late model J1 Has high input goes to V1a and early 80’s model J1 high go to V1b. Is there’s any difference in gain structure and sound going before or after the cold clipper load of J2 low?
Hi, I found this video after watching your 83 2204 repair video. I have an 81 2204 which is killer but I don’t get the amount of gain you are getting in this vid only if I set the preamp on 10. I tried the settings in your 83 2204 video but the tone get is like ice pick central and nowhere near as much gain. Could you tell me what settings you had on the amp for this one? Great video by the way and very interesting. Cheers from England
I think the title in this video is misleading... The stock JCM 800 was messed up and wired wrong before he got it. That's why it sounded so dull. The differences between the Horizontal and vertical inputs isn't that big. It's a bit confusing and I hope there will a added a disclaimer to the video in the future. 🙂
I have a 4104 from 89 ... at r29 it has an 8.2k drop resistor. can i replace it with a 20k drop resistor and connect each part of c21 to each end of this 20k new drop resistor? Thanks for Your channel...the JEL mod it's amazing
Agreed the amp sounds great, but didn’t the 2204 and 2203 have vastly different B+ voltages, 368VDC and 470VDC? Thus the JCM-800 wired as your one is and a JCM-800 with a 368VDC B+ would sound different?
What cracks me up is the internet is flooded with “the latest greatest Marshall amp sims and modellers” and everyone says they are just as good as the real amp. Every time I’ve heard and played a modeller, never ever sounded like a real Marshall. And honestly I think they will never recreate a Marshall digitally no matter how fancy computers get.
Agree! The real problem with modellers surfaces when you try to amplify them through a cab…falls short. The are fine into studio monitors, recording or whatever but fall flat if you try and use them as backline. Tube amps are instruments!
finally i made the mod of my 2204 and reconfigured the filtering ... now when I activate my zeroloss metroloop the sound becomes similar to out of phase and makes a very strange metallic sound ... any sugestión that I have done wrong? thanks
question. jcm800 robinette build. my Phase inverter supply is reading 400V so i ran a 10k between the filter cap and PI supply node but still getting 400V. the 10k did nothing to reduce the volts and 400 volts seems high? your PI supply here is 321 volts
Technically speaking, it has slightly less gain than before. Less voltage usually has the percievable effect of more distortion or "browning" the tone. What's not so obvious is how it got clearer; usually more voltage equals brighter, more clarity and note separation but it could just be allowing the high mids come through more and less low mids which can muddy up the tone. Might also be less parasitic capacitance in the prramp stages by removing the hot shield, which sounds the most plausible. Whatever it is, copying the early 80s recepie lead to arguably the sweetest results
Thanks for the explanation. I have a '89 2204 in perfect condition. Stored in a recording studio. Everyone who has heard it says it's the best JCM 800 they have ever heard. But personally from the examples in this video I'm jealous of the tones after the mod. Sounds gorgeous!
I just sold my 900 and I want to build a replica of a 800 2204, but now I am not sure what to build, vertical vs horizontal inputs, 3 caps vs 6 caps?? or a JMP?? MK2 MK what? Additionally, what transformer to buy ? Is better a kit or buy the parts apart? Any recommendation will be appreciated Great channel btw.
2204, vertical input spec with 3 x dual can caps is the way. If it’s your first build and you are not experienced get a kit from Ceriatone. If you want to choose your own parts, then purchase my Marshall 2203/2204 PCB and use that as your backbone for the build.
With that sound you really make me do a leap of faith. I just bought a stock 1986 JCM800 2204 just to do that mod. Can you share pictures of the actual layout for all the changes? I got the schematics.
Awesome content.. I am about to change something in a Friedman SS100. I am trying to get it more to 68 or 69 SLP specs. But I cant decide. The screens are 16pf as a 68 would be but there are some other changes involved. I am running the amp with the presence on 8 currently and its fine but i whish a little bit more of a cleaner sound with more snarl like your modded jcm800 studio or even the modded 1987x. Hard to tell as Ive never played both amps in person. Maybe someone can chime in?
@@HeadfirstAmps wow thanks for the quick response.. i had that on my mind but i thought it would not affect the tone when the gain is cranked anyway.. but i will try! I could not use the amp with the gain below 5 or 6 anyway as it was too muffled regardles off treble and presence so it will be more usable through its range im sure. Thanks a lot! Subscribed
Awesome.. Also, be aware that the SS treble pot is audio taper rather than linear, meaning you really need to wind it up to replicate what a regular Marshall's treble pot would be doing tone wise. E.g. 9/10 = 5/10
@@HeadfirstAmps Yes I knew that but really appreciate your response, that information is helpfull for all new to this amp.. thats exactly how i run it.. about 4 o' clock on the treble.. I dont understand that really why they used a audio taper pot for that.. a linear one would have been just fine. Anything below 12 o clock is useless in my opinion on that amp. What I really liked about my SL68 was that it had this fuzzyness in the highs when turned on 10 but I was more into steve stevens exposed sound than early evh. Still not sure wether his was a 68 or 69 Plexi as the transition happened somewhere in between with the higher filtering 16pf vs 50pf. I read it was a 69 somewhere but his amp was somewhat special and I believe something was done until the 90s. So my best bet was to by a Friedman SS 😀 to get that sound. I could not turn up an SL68 in a live situation even with an attenuator due to reliability. I was scared running it on 10 and eating tubes for breakfast, so the SS100 was a good compromise while being a little bit darker but now with IRs and whatever you can really change that. Sorry I could probably talk all day about that stuff.
I like the SS, I found that you just gotta crank that treble pot right up and set the gain on around 7 or 8. A 250pf bright cap, with the gain on 7 would you you there.
That was super interesting Jason! Thank you for this video. The lower voltage makes so much sense - I guess that’s what EVH was doing with the Variac as well. Btw, the early 80s spec amp sounds fantastic. More open, more gain, more bite. Very cool!
I know this is an older vid, but just now coming back to trying to get some chops back, and my '85 JCM 2204 has always been a bit of a downer for me. I would love to see a step by step of the mod. One way or another, I'm gonna give this a try. Thanks!!!
I own this very model…an 86 2204….That’s amazing the difference in sound between the 80 and 86……I was always told they were identical…now I want to “fix”mine…
My 84 4104 with horizontal inputs is the best sounding Marshall I've owned, probably played. I always thought JMP and/or vertical input was the best. Not always the case.
Thanks for the great informative video. I've come across many of this era amp with the input wire shield connected to the plate, but it has always been a thinner gray wire, and I believe it is stock. The biggest issue I have with these amps was not addressed, and that is the snubber cap on the first gain stage between the plate and cathode. It is on the board but was not on the schematic, although I have seen it on schematics. It is on all 2 hole and 4 hole amps following the board redesign. It takes off a lot of audible top end, but remove it and the amp will oscillate... bandaid fix for poor layout/design?
wow, just got to the play through bit. it's a massive difference. the 86 sounds woolie and dull like a blanket's over the speaker box. that's a bad update by Marshall. still, I think your Headfirst amp sounds bigger and more present and way more adjustable.
Regarding the input coax shield connected to the plate, yeah that would seem strangely odd. When I was building my 20 watt Plexi I took it upon myself to include a PPIMV. Part of the procedure involving the configuration of that was to place the -55 volt bias voltage on the shield of of the wires going to the PI. I thought this very strange. There was a very brief explanation along the lines of it setting up a form of common mode rejection action. I never really wrapped my head around how that applied to that situation but, I must say, my PPIMV is very well behaved and the amp is extremely quiet. I had to wonder if someone was riding on some theory of that plate voltage providing an extra level of noise immunity. I just dunno....
I'm amazed that you put so much time effort and expertise out here for free, for anyone who wants it. Thank you. Do you know anything about the 2205/2210 line of Marshalls? I've heard there were changes over the years and I'm trying to track down what those were.
Hi Eric, thanks man! Well, I have a passion for it so it's a pleasure to share! I believe the changes between the 2205 & the 2210 are fairly subtle, although it has been a while since looked into them. There is a clip up of a 2205 that I modded, they can be made to sound pretty decent with a fair bit of work.
I have a 1983 horizontal 2203. All stock. It seems like I have the first horizontal because 1985 seems to be the year they did this. How can I have an 83 and what filtering do I have?
Hey Jason, very informative! I have a friend who has a 4 hole JCM 800, the 1959 spec, but from 1987, and it's got the same filtering changes as the amp in this video, so it's loud and quite brittle. I might change the filtering like you have done here, and see if it sweetens it up a bit, steer it more towards the sound of my reissue 1959, which is beautiful.
Wow awesome video...! 😀 Would you be so kind to help me with something, I'm struggling to understand: This mod you did in this video. Was it basically, converting the JCM 800 back to the original MV 2203? As I understand it, there is no difference in circuit, between the JMP 2203 and the vertical inputs JCM 800? Thank you. 👍 Every horizontal JCM 800 I have heard, sounded different, very confusing... 😖😄
great vid I bought JCM 800 2204 one with X in serial number so 1989 horizontal Input someone added effects loop bypassable with switch amp sounds great I even like pre amp back a bit for cleans and when pre amp around 7 with master 6/7 with boss SD1 sounds great , would you recommend any mod to give it abit more gain or bite/ top end roll off , keep up the great work greetings from Ireland.
the old spec sounds too bright to my ears , i own an 88 horizontal and find it plenty bright , tho mine is/was actually a combo that i mounted in a home made headshell , i get many comments on how good mine sounds tho i use it more as a pedal base than cranked
I've got an '81 2204 vertical input. My B+ sits about 360-370v. The amp sounds somewhere between your two sound clips. Not as bright as the 80 spec and not as wooly as the 86. I wonder if there have been any other design tweaks along the way. I may have to open it up now and trace the circuits. I also run a Hall amplification VVR in it anyway (only controls the power and PI sections), but I sometimes feel the amp would sound tighter with a higher plate voltage.
fantastic video. learning so much from you. any way you would upload to axechange your patch? i have a suhr loadbox and two notes irs and want to give your recording path a try against my standard mics! or just axe3 straight in.
When you were playing What’s Next to the Moon, it was almost like the ‘86 was a Malcolm tone and the “80 was Angus. I had always thought apart from the move to PCB mounted pots and jacks, 2204’s didn’t change circuit wise and it was the 2203’s where they changed the filtering layout. Never too late to massage the grey matter…lol
Yeah, same amount of filtering in the latter year 2204’s but for some strange reason Marshall configured the filter caps differently which makes the amp too stiff and brittle imho.
@@HeadfirstAmps I really first heard the difference it makes years ago when I got my Mesa Stiletto. Even though Rec’s have had it since the early 90’s, they’re such a soft amp to begin with I didn’t see much of a benefit. But the Stiletto being so much more percussive and tight I could here it sweeten up the top end and put just a little more “stringy-ness” under the fingers without sacrificing articulation. My MK V is the same on Variac setting. I like the versatility it adds.
@@HeadfirstAmps I really first heard the difference it makes years ago when I got my Mesa Stiletto. Even though Rec’s have had it since the early 90’s, they’re such a soft amp to begin with I didn’t see much of a benefit. But the Stiletto being so much more percussive and tight I could here it sweeten up the top end and put just a little more “stringy-ness” under the fingers without sacrificing articulation. My MK V is the same on Variac setting. I like the versatility it adds.
They call that hot shielding I think....they use the capacitance in the shielded cable to stop oscillation...but you probably figured that out by now...I read it somewhere.....
I feel like I’m in college but instead of boring classes I’m getting what I’m excited about learning. You should be the professor of Tube amp degree 😀
If only everyone weren’t listening to Cardi B and acting like they have a 59 IQ it would pay off too.
Those tone comparison clips are excellent. They really show the difference. Yeah the early circuit is brighter with more harmonics. And more crunchy. It's definitely better sounding. Good video!
Those horizontal input 800’s a great example of cost cutting gone wrong. Like Fender in the CBS era. But!! As you’ve pointed out, once fettled a little, absolute monsters. When I saw Zak with Pride and Glory you’ll notice all he seemed to use was horizontal in put 800’s (no doubt they were modded, probably Lee Jackson) Definitely something about them. Don’t get rid of it mate 😉
It's a keeper!
It's called the hot shield. Supposedly it decreases noise, I've also heard that it gives a cocked wah type sound not sure about that, but I've also read that on later models they just used the 100pf cap to cut parasitic interference. Idk how true any of this is, but yeah the hot shield I've read a lot about .
I actually liked the later 86 sound it sounded clearer, with more headroom and the high end wasn't so raspy.
I actually did a search in TH-cam looking to see if I could find a higher voltage 2204, but with a 20k preamp dropping resistor going towards the preamp. My idea was to try to keep the power section cleaner for more headroom, but drop it back down for the preamp. Nice amp and tones you have there, nice work also ☺️
Another great vid and incredibly informative! I bought a 100w one of these new when I was 17 (and yes I ran an SD-1 with it too). It was a great reliable amp but the amp gain always sounded a bit flat and listening to this vid just took me straight back there. I ran a Soldano Hot Mod for a bit which was cool (if not a bit noisy), and then I got a Soldano SP77 and had the amp modded to bypass the preamp - that combination absolutely kicked ass. The early 80's version mod really brought it to life and I can now understand why people chase after the JCM800's now.
It's one of the sounds of rock and roll, isn't it
Actually the horizontal input 100w 800’s are different again, they have less filter caps in than the earlier amps and are the most aggressive sounding 800’s of all. I think the metal players chase those versions. Check out Euge Valovirtas channel. He explains and demos the difference.
@@vintagesound8112in which way "more aggressive"? I have one and I confirm it drives me mad for how stiff, harsh and bright it is.
Euge Valovirta's 800 are modded.
Great information and comparison. I never owned a jcm but when I come across one of these it’s good to have this info. I’m stuck with 3 JMP amps for now 😄
'80 spec all the way ever. Great sound awsome video as always.
Thanks 👍
Sounds awesome man! Hahaha I love that you're keeping the amp too.
Im not sure if it is due to lower voltage in the phase invertor (allowing less muddy low mids or something) or reworking the shielded inputs for less parasitic capacitance bleeding the highs, but there's a dramatic difference in clarity with the early 80s recepie. It's pretty astounding, actually
jason is the best with marshalls you will find.great restore mate
Great video! Thank you so much for breaking this down in such detail. Much more than I could absorb but I get the idea. I doubt I would ever be ambitious enough to take on that mod but I'm knocked out that you are an amazing tech, know how to get great tone and you are a good player too!
I have 3 early 80's vertical input 2204 amps and I will probably take them to my grave. Nothing beats the sound. Please tell me what speakers are you using and how were you recording the audio from the speakers?
Thanks man. That's recorded via a Suhr reactive load with ML Soundlab IR's (GB & V30 blend).
Late 80s sounds like ass, dark, and like a blanket over it!! Easy enough to fix, which you did! :)
I have a late-80s coming in this week, so will be fixing the B+ issue among other things.
My 2204 is a vertical input from '85. It probably my best sounding Marshall. And I have two 70's Jmp's. It's a difference playing at home or in a band. There is a reason Marshall did what they did.
Thanks for making all these awesome informative videos
Glad you like them!
Like taking off the blanket, I love it
i have this exact amp ( look to your left ) and love it especially when i pare it with my Fender deluxe it is THE tone ,, wouldn't change a thing
I first heard about the shielded cable going to earth from Gerard Weber, he claimed it stops high freq oscillation, for a laugh I tried it on the input of my amp and it sounded duller.
I have seen it implemented in Trainwreck amps on the wiper of the tone controls return stage and it has an 820 ohm in the valve socket and the cable is mounted to the other side of the 820 ohm. That works fine.
Yeah, having 300vdc on the coax of a signal path that goes to your guitar is not my idea of a safe mod.
This is one of the few 1986 models I’ve seen where the cloth hasn’t turned fawn brown. My first 800 was an 86 with that feature and I’ve had a soft spot for 86 models in particular ever since.
Wow. I was going to start a Headfirst Cali build but I"m now actually considering just building a 2204 clone :-)
I have a 1986 2204s classic limited edition small box, totally stock .and it sounds like the vertical input model .nowhere near as dark as this horizontal one sounds. The last thing I would want is to make it sound any brighter.
I always take the shielding to the plate. It's really the best way. I know some ground on the cathode pin, as well.
the hot shield...like 300vdc on the coax shield? That's not for me, I don't consider it safe.
That is absolutely astonishing how different it sounded before and after. I've always heard the stories of how the horizontal inputs sounded bad but this really showed off in comparison the real difference. My 2204 is from '81 so for all intents and purposes it's a JCM800 version of the old Rose Morris era 70's amp with different cosmetics. Why do you think Marshall made changes for the worse tone-wise? I get the cost-saving measures of the all-on-the-board, but why change the circuit to sound "less good"?
The 2203 changes were definitely to same money, as they stripped out the 1/2 the filter caps. For the 2204's....hard to say why, but the higher voltages through the pre amp definitely make them very "strident".
@@HeadfirstAmps Very interesting. I guess cost-cutting took precedence over tone. To me, the early JCM 800's were the last of the great, classic Marshalls.
The shield connected to the plate is a way to incorporate the cable capacitance as negative feedback at high frequencies. I have heard about this being done in amps but haven't come across it before either. I think they said Mesa used to occasionally do this when hand wired? It is a way to drastically reduce gain at high frequencies. I don't recommend it.
I have since learned this, and must be the reason the amp sounded so dull
@@HeadfirstAmps This amp sounds absolutely awesome! I have come back and replayed the clips multiple times today. Great Job!
The early 2203 2204 had that..very common to see it, they use to put a blob of silicone on the wire to the chassis to keep it in place.
Great video, I wonder if the 800 schematic in Headfirst web page (The one you can download in gif I think) has the correct voltages I should aim? I am about to build another 800 and I want to be sure to follow the ultimate JCM800 schematic. Id appreciate your help !
The anomaly of the reversed shield ground of input to V1 grid and anode existed I a few of the year 1983/1984 model 2204’s I encountered. Shock hazard but stock believe it or not. I have never encountered it though in a horizontal input so this may have been a poor decision of an individual mod following Marshall’s anomaly.
David Hopkins
The more I looked at this one, the more I realised it had been tinkered with!
Incredible video, thanks
Thanks!
I liked the video and the initial comparison, but you said you were going to run the same clips through at the end. Instead you changed guitars and played very different notes. I don't have the comparison so I am not completely convinced. It is a nice technical presentation of the schematic differences in the two amps. And you showed the voltage changes.
Thanks. From 2:05 is where I do exactly that. I recorded into a looper, the same riff, and then A/B the before and after.
You are saying the comparison was edited into the beginning of the video. That is an amazing difference. I'm curious are the transformers the same? 1202-324 pt, 784-139 ot, 1471-263 choke.
Argh 🥴 that sounds killer, I need it.
So glad I did the work to put it to 80's spec, and that 'hot shield' coax clearly was impacting the tone. I learnt that this era of amp needs to be thoroughly checked over, as most will have been modded to some degree.
Ive got an 84 with Horizontals. 2/7/84 on the chassis sticker.
Can you show the voltages again like on this video but with EVH browned out preamp voltages? With the heaters low please?
Cheers
Does the same apply for 2203?
I have my 2203 (86') I got it as that was my dream amp. It sound so muddy! One of my worst amps. This video probably save me some cash to replace it for youngest model! Could you let me know if i can base on your video modding my 2203? I see it's not different on diagrams, hence my question. Thanks a lot!
This will only work for a 2204 50W. If your amp is super muddy then it’s probably been modded, find a good tech to return it to stock.
Question: did the change the PCB itself when the went from vertical to horizontal inputs was it effectively the same board?
Yeah Marshall changed completely the board
Is it just me or the amp sounded better before the mods? No disrespect though. Great work.
There is also another difference, late model J1 Has high input goes to V1a and early 80’s model J1 high go to V1b. Is there’s any difference in gain structure and sound going before or after the cold clipper load of J2 low?
Hi, I found this video after watching your 83 2204 repair video. I have an 81 2204 which is killer but I don’t get the amount of gain you are getting in this vid only if I set the preamp on 10.
I tried the settings in your 83 2204 video but the tone get is like ice pick central and nowhere near as much gain.
Could you tell me what settings you had on the amp for this one?
Great video by the way and very interesting.
Cheers from England
I think the title in this video is misleading... The stock JCM 800 was messed up and wired wrong before he got it. That's why it sounded so dull. The differences between the Horizontal and vertical inputs isn't that big. It's a bit confusing and I hope there will a added a disclaimer to the video in the future. 🙂
So what exact year and exact model has the best overall quality in hardware and sound ?
For the 2203/2204 amps. late model JMP's and early JCM800 series up to around 1983/84. imho...
@@HeadfirstAmps what should i look for when buying any of these? Do you prefer amp heads or is the 4103 combo model worth it ?
I thought you were going to hug the amp.
I have a 4104 from 89 ... at r29 it has an 8.2k drop resistor.
can i replace it with a 20k drop resistor and connect each part of c21 to each end of this 20k new drop resistor?
Thanks for Your channel...the JEL mod it's amazing
Feel free to email me some pics at headfirst.amplification@gmail.com and I'll be happy to have a look
@@HeadfirstAmps thanks...email sent
Agreed the amp sounds great, but didn’t the 2204 and 2203 have vastly different B+ voltages, 368VDC and 470VDC?
Thus the JCM-800 wired as your one is and a JCM-800 with a 368VDC B+ would sound different?
The earlier 2204's (JMP era) had that low voltage. This 2204 had a 460v plate voltage, so very similar to the 2203 in that regard.
What cracks me up is the internet is flooded with “the latest greatest Marshall amp sims and modellers” and everyone says they are just as good as the real amp. Every time I’ve heard and played a modeller, never ever sounded like a real Marshall. And honestly I think they will never recreate a Marshall digitally no matter how fancy computers get.
Agree! The real problem with modellers surfaces when you try to amplify them through a cab…falls short. The are fine into studio monitors, recording or whatever but fall flat if you try and use them as backline. Tube amps are instruments!
Wow, the 86 is dark.
finally i made the mod of my 2204 and reconfigured the filtering ... now when I activate my zeroloss metroloop the sound becomes similar to out of phase and makes a very strange metallic sound ... any sugestión that I have done wrong?
thanks
Hi, happy to take a look if you'd like to post some detailed pictures of your mods in my DIY Builders group on FB.
question. jcm800 robinette build. my Phase inverter supply is reading 400V so i ran a 10k between the filter cap and PI supply node but still getting 400V. the 10k did nothing to reduce the volts and 400 volts seems high? your PI supply here is 321 volts
If you're not getting a voltage drop then either its not wired correctly or the amp isn't drawing any current (e.g. No tubes in)
@@HeadfirstAmps i figured it out. The B+ from the cap to PI wasn't connected to the dropping resistor (6.8k) it was going straight through.
I'm surprised that is has more gain after the mod. Isn't the JCM 800 supposed to have more gain than the original 2203/4?
Technically speaking, it has slightly less gain than before. Less voltage usually has the percievable effect of more distortion or "browning" the tone.
What's not so obvious is how it got clearer; usually more voltage equals brighter, more clarity and note separation but it could just be allowing the high mids come through more and less low mids which can muddy up the tone. Might also be less parasitic capacitance in the prramp stages by removing the hot shield, which sounds the most plausible. Whatever it is, copying the early 80s recepie lead to arguably the sweetest results
Thanks for the explanation. I have a '89 2204 in perfect condition. Stored in a recording studio. Everyone who has heard it says it's the best JCM 800 they have ever heard. But personally from the examples in this video I'm jealous of the tones after the mod. Sounds gorgeous!
I just sold my 900 and I want to build a replica of a 800 2204, but now I am not sure what to build, vertical vs horizontal inputs, 3 caps vs 6 caps?? or a JMP?? MK2 MK what?
Additionally, what transformer to buy ? Is better a kit or buy the parts apart?
Any recommendation will be appreciated
Great channel btw.
2204, vertical input spec with 3 x dual can caps is the way. If it’s your first build and you are not experienced get a kit from Ceriatone. If you want to choose your own parts, then purchase my Marshall 2203/2204 PCB and use that as your backbone for the build.
@@HeadfirstAmps thank you for your answer, I am getting the parts and a qualified technician will build it. Where can I find your PCB ?
Did you change the tubes and circuit to 6550 tubes or stock EL34?
Kept the EL34s
With that sound you really make me do a leap of faith. I just bought a stock 1986 JCM800 2204 just to do that mod.
Can you share pictures of the actual layout for all the changes? I got the schematics.
Instead of adding the extra 10k 2w resistor it will be the same putting a 20k 4-5w resistance?
Awesome content.. I am about to change something in a Friedman SS100. I am trying to get it more to 68 or 69 SLP specs. But I cant decide. The screens are 16pf as a 68 would be but there are some other changes involved. I am running the amp with the presence on 8 currently and its fine but i whish a little bit more of a cleaner sound with more snarl like your modded jcm800 studio or even the modded 1987x. Hard to tell as Ive never played both amps in person. Maybe someone can chime in?
I'd try a bright cap on the gain, I don't think the SS has one. Try 250pF to 500pF to taste.
@@HeadfirstAmps wow thanks for the quick response.. i had that on my mind but i thought it would not affect the tone when the gain is cranked anyway.. but i will try!
I could not use the amp with the gain below 5 or 6 anyway as it was too muffled regardles off treble and presence so it will be more usable through its range im sure. Thanks a lot! Subscribed
Awesome.. Also, be aware that the SS treble pot is audio taper rather than linear, meaning you really need to wind it up to replicate what a regular Marshall's treble pot would be doing tone wise. E.g. 9/10 = 5/10
@@HeadfirstAmps Yes I knew that but really appreciate your response, that information is helpfull for all new to this amp.. thats exactly how i run it.. about 4 o' clock on the treble.. I dont understand that really why they used a audio taper pot for that.. a linear one would have been just fine. Anything below 12 o clock is useless in my opinion on that amp. What I really liked about my SL68 was that it had this fuzzyness in the highs when turned on 10 but I was more into steve stevens exposed sound than early evh. Still not sure wether his was a 68 or 69 Plexi as the transition happened somewhere in between with the higher filtering 16pf vs 50pf. I read it was a 69 somewhere but his amp was somewhat special and I believe something was done until the 90s. So my best bet was to by a Friedman SS 😀 to get that sound. I could not turn up an SL68 in a live situation even with an attenuator due to reliability. I was scared running it on 10 and eating tubes for breakfast, so the SS100 was a good compromise while being a little bit darker but now with IRs and whatever you can really change that. Sorry I could probably talk all day about that stuff.
I like the SS, I found that you just gotta crank that treble pot right up and set the gain on around 7 or 8. A 250pf bright cap, with the gain on 7 would you you there.
I have a 2203, is it the exact same mod compare the 2204?
Not exactly the same because the 2203 filtering is different. What year is your 2203?
@@HeadfirstAmps I also have a 2203 with horizontal inputs. I think it´s from 1989. What would be different to the 2204 mod?
Thanks and greetings,
Jan
@@HeadfirstAmps hi Jason my 2203 is a 1986
Wow, the 86 spec sounds like ass compared to the 80 specs!
That was super interesting Jason! Thank you for this video. The lower voltage makes so much sense - I guess that’s what EVH was doing with the Variac as well. Btw, the early 80s spec amp sounds fantastic. More open, more gain, more bite. Very cool!
Great tones, and much improved after your tweaks. Love the extra brightness and aggression it adds.
Perfect 800 tones!
I know this is an older vid, but just now coming back to trying to get some chops back, and my '85 JCM 2204 has always been a bit of a downer for me. I would love to see a step by step of the mod. One way or another, I'm gonna give this a try. Thanks!!!
If you’re on FB, post your questions in our DIY Builders group.
how it went?
Welp. Off to reverb it is boys!
I need this in my life.
Both sound nice but love that '80 spec tone.
It was 1984 that horizontal inputs debuted
I own this very model…an 86 2204….That’s amazing the difference in sound between the 80 and 86……I was always told they were identical…now I want to “fix”mine…
My 84 4104 with horizontal inputs is the best sounding Marshall I've owned, probably played. I always thought JMP and/or vertical input was the best. Not always the case.
Thanks for the great informative video. I've come across many of this era amp with the input wire shield connected to the plate, but it has always been a thinner gray wire, and I believe it is stock. The biggest issue I have with these amps was not addressed, and that is the snubber cap on the first gain stage between the plate and cathode. It is on the board but was not on the schematic, although I have seen it on schematics. It is on all 2 hole and 4 hole amps following the board redesign. It takes off a lot of audible top end, but remove it and the amp will oscillate... bandaid fix for poor layout/design?
wow, just got to the play through bit. it's a massive difference. the 86 sounds woolie and dull like a blanket's over the speaker box. that's a bad update by Marshall. still, I think your Headfirst amp sounds bigger and more present and way more adjustable.
Regarding the input coax shield connected to the plate, yeah that would seem strangely odd. When I was building my 20 watt Plexi I took it upon myself to include a PPIMV. Part of the procedure involving the configuration of that was to place the -55 volt bias voltage on the shield of of the wires going to the PI. I thought this very strange. There was a very brief explanation along the lines of it setting up a form of common mode rejection action. I never really wrapped my head around how that applied to that situation but, I must say, my PPIMV is very well behaved and the amp is extremely quiet. I had to wonder if someone was riding on some theory of that plate voltage providing an extra level of noise immunity. I just dunno....
The 80 spec sounds more open and brighter, and the 86 spec sounds more compressed and darker to my ears, I like both versions though
Great playing and great tone. And anybody who loves Powerage is a friend of mine.
'86 spec sounds so muddy.
Hey Jason do you have any low cost oscilloscope and signal generator recommendations?
My mate Scott picked one up the same as mine on Amazon for AU$330. A Hantek DSO5102P.
Shall we do that "mod" to the JCM800 reissues or are these already to the 80's specs?
The 2203x is true to the vertical input spec
I'm amazed that you put so much time effort and expertise out here for free, for anyone who wants it. Thank you. Do you know anything about the 2205/2210 line of Marshalls? I've heard there were changes over the years and I'm trying to track down what those were.
Hi Eric, thanks man! Well, I have a passion for it so it's a pleasure to share! I believe the changes between the 2205 & the 2210 are fairly subtle, although it has been a while since looked into them. There is a clip up of a 2205 that I modded, they can be made to sound pretty decent with a fair bit of work.
I have a 1983 horizontal 2203. All stock. It seems like I have the first horizontal because 1985 seems to be the year they did this. How can I have an 83 and what filtering do I have?
Hey Jason, very informative!
I have a friend who has a 4 hole JCM 800, the 1959 spec, but from 1987, and it's got the same filtering changes as the amp in this video, so it's loud and quite brittle.
I might change the filtering like you have done here, and see if it sweetens it up a bit, steer it more towards the sound of my reissue 1959, which is beautiful.
Wow awesome video...! 😀
Would you be so kind to help me with something, I'm struggling to understand:
This mod you did in this video. Was it basically, converting the JCM 800 back to the original MV 2203? As I understand it, there is no difference in circuit, between the JMP 2203 and the vertical inputs JCM 800?
Thank you. 👍
Every horizontal JCM 800 I have heard, sounded different, very confusing... 😖😄
I am sorry, but i`m having big trouble following your explanations.
Can you draw a simple schematic of what you actually changed please?
Best regards
great vid I bought JCM 800 2204 one with X in serial number so 1989 horizontal Input someone added effects loop bypassable with switch amp sounds great I even like pre amp back a bit for cleans and when pre amp around 7 with master 6/7 with boss SD1 sounds great , would you recommend any mod to give it abit more gain or bite/ top end roll off , keep up the great work greetings from Ireland.
the old spec sounds too bright to my ears , i own an 88 horizontal and find it plenty bright , tho mine is/was actually a combo that i mounted in a home made headshell , i get many comments on how good mine sounds tho i use it more as a pedal base than cranked
Great video. I'm convinced!
Lowering the voltages took the blanket off.
Good information 👍
I've got an '81 2204 vertical input. My B+ sits about 360-370v. The amp sounds somewhere between your two sound clips. Not as bright as the 80 spec and not as wooly as the 86. I wonder if there have been any other design tweaks along the way. I may have to open it up now and trace the circuits. I also run a Hall amplification VVR in it anyway (only controls the power and PI sections), but I sometimes feel the amp would sound tighter with a higher plate voltage.
Spot on, the early 2204's had your B+. Mine is now like a 2203 plate voltage but in 50w guise.
fantastic video. learning so much from you. any way you would upload to axechange your patch? i have a suhr loadbox and two notes irs and want to give your recording path a try against my standard mics! or just axe3 straight in.
Thanks Stephen. Sure, I'll load it up.
@@HeadfirstAmps thanks. ill be looking for it
When you were playing What’s Next to the Moon, it was almost like the ‘86 was a Malcolm tone and the “80 was Angus. I had always thought apart from the move to PCB mounted pots and jacks, 2204’s didn’t change circuit wise and it was the 2203’s where they changed the filtering layout. Never too late to massage the grey matter…lol
Yeah, same amount of filtering in the latter year 2204’s but for some strange reason Marshall configured the filter caps differently which makes the amp too stiff and brittle imho.
@@HeadfirstAmps I really first heard the difference it makes years ago when I got my Mesa Stiletto. Even though Rec’s have had it since the early 90’s, they’re such a soft amp to begin with I didn’t see much of a benefit. But the Stiletto being so much more percussive and tight I could here it sweeten up the top end and put just a little more “stringy-ness” under the fingers without sacrificing articulation. My MK V is the same on Variac setting. I like the versatility it adds.
@@HeadfirstAmps I really first heard the difference it makes years ago when I got my Mesa Stiletto. Even though Rec’s have had it since the early 90’s, they’re such a soft amp to begin with I didn’t see much of a benefit. But the Stiletto being so much more percussive and tight I could here it sweeten up the top end and put just a little more “stringy-ness” under the fingers without sacrificing articulation. My MK V is the same on Variac setting. I like the versatility it adds.
They call that hot shielding I think....they use the capacitance in the shielded cable to stop oscillation...but you probably figured that out by now...I read it somewhere.....