I really love your non invasive, easily reversible, Totally effective mods. As a vintage Marshall collector and enthusiast, this has easily become my new favorite channel.
Great video, J! Glad to see this being put out there. Priceless info for some of these guys who are starting to learn. Wish these videos were around when I started modding amps. I had to settle for 1980's Lee Jackson videos!!
My 2203 build has mustards and 32u on the pre amp 50u on the phase inverter and a tube buffered effects loop.....with the 22k presence .1u and 4k7 combination....variable depth....and stock other wise.....with a 4x12 with v30s and g12h30s.....and 400 volts on the plates.....it's a great blues amp.....I love it
Excellent ...thank you for this info!! I'm doing your #34 mod to my 2203 now... didn't realize I could just keep the 470p cap on the 100k from the JEL mod in place without moving to the socket pins/resistor. thank you!
Jay I like how you always just show how the amp sounds purely on its own. So many people do demos with a backing track and thier amp going thru a DI / DSP. When I hear a demo, I at least, want to hear a what the amp sounds like live. Im sure Im not alone in this! Of course, love your playing too.
Excellent video, tone, and playing! Thanks for going into detail of the mods - love the final result with all of them in it. I need to get my ‘78 2204 sounding like that.
Thanks, all the individual bits work together don’t they. I think maybe just the depth mod and the 2k7//0.68 cathode might be enough for strats and teles but with humbuckers thinning out the preamp is crucial.
Love these videos Jason, especially the audio comparison of what each stage of the mod is doing to the tone... that is a LOT of work to stop and record each step, then continue. But its so helpful! Personally, I prefer the stock tone, but I can see a lot of people would love where you took this. It doesn't sound bad at all, I'm just more 70s rock and less metal. :) I also learned a LOT from this video about what is going on in the circuit of my '76 JMP. There were some non-standard wiring bits that I had been wondering about, that you have explained here, like the coax from the gain pot to V1B, which mine seems to have, though in my amp they left the grid stopper in place on the board and ran the coax from there. The wiring also seems to split at the socket, white wire to the grid and the black to the screen. Ever seen that? I don't have the coax from the master pot to V1A though, do you think that's worth doing to reduce noise even in a non-modded amp? I notice that your amp seems to have the white goop on the chassis and board that mine does as well... do you know what that stuff is for? Was it just there to hold leads in place? It sure is a mess! Cheers!
So I finally got a lead on an Origin 50. Looking forward to breaking out the soldering iron again and hitting you up for some parts. I love the knowledge, the sounds, and playing on this channel. Keep on rocking Jason!
After I complete the rebuild of my 1980 2203 that was heavily modified before I bought it, I'm going to swing back around here and try out all of these mods. They sound fantastic! The old PCB has been swapped out for a PTP turret board so I can easily make tweaks without worrying about breaking traces, etc. You have my favorite channel on RU-vid Jason!
I think that .22 cap is breaking in cause it's starting to sound better....the strings feel like they are an inch thick when the zeners are on....I love it man it's awsome
Best and most useful guitar amp channel on the internet!! Thank you for your help! Also this is the best modding video ever created, we need more of this!!
Hiya, OMG just what have you done!!! It had been totally wrecked by some previous donkey and you have gone in and totally TOTALLY improved it 😁. Hehe. I have a 78 2203 and the chassis has been out 3 times for a dust and grinning session, not touched and she's beautiful, BUT I do like the full mod sound 👍 Top video and tutorial, well done lad.
I've got a Marshall, but it happens to be a newer Marshall MA100C 100W Valve combo amp, a mate of mine did some service work on it because it was blowing fuses, turned-out the stock power transformer wasn't properly rated for our Australian 240V AC mains supply, it was rated for the Uk 230V AC supply so it was putting-out too much HT, and over-stressing the four EL34 power tubes, one of them actually suffered an arc-over on the octal socket which left a bit of carbonizing between two socket pins.
Awesome, gonna be really helpful cos I built a 5watt amp like 12years ago and wasnt happy with the sound. I used a 6v6 5watt power amp section. I was planning to build it with a 1959 preamp, but had decided to go for a 2203 jcm800 preamp instead since I play higher gain stuff usually. It didn't really turn out as expected. I know it will lose something from not having a phase inverter, since it's a single ended amp. But It's not even really a gain thing, if it was just low gain i could push it with a pedal, it's more just a lack of low end and thickness. These mods will help get it into a good "known" position and then I can work from there to get it where i want it.
FFS, all of these amps you mod sound sick af. Huge bonus that your a great player as well...it's nice to here these amps played like they should be. #DialedIn
I've got an old mid-70's (I think) non-reverb Fender Super Twin amp, the one with the Distortion knob, it uses six 6L6 power tubes (Yikes!!!) to generate 180W RMS, or a whopping 395W peak power output, anyway, I recently had to replace five old carbon comp resistors in the circuitry associated with the V1 7025/12AX7 preamp tube, because the old resistors generated some loud crackly noise, I replaced them with some new 5%/1W carbon film resistors and that fixed it, the six 6L6 power tubes are all STR types, the amp is housed in a wooden head cabinet and I will be using it as part of a bass amp rig with a Peavey 410TX cab I'm in the process of restoring, these old Fender Super Twins make really good bass amps, they are equivalent to about 2/3rds of an Ampeg SVT.
Hey Jason I done the hybrid 10k with a .22 cap and used 220k to ground when the zeners are off. On a post eq master....now if there was something to do to bring back the eq like it was before that would be something.....the eq response seems to change a little and is kind of like compressed a little ..I don't know but it definitely takes some twerking to get a tone like that.....I also have the variable depth mod with a 47k resistor....it works good
I think a cool video would be one about controlling the ice picky highs with plate snubbers.....how and where to use them and what values to use with these high gain mods
I still have my stock 2204 JMP which I bought brand new in 1980 when I was 16. It’s totally stock , tubes ,caps , transformers. No mods . Still sounds great. Also have a 2104 combo JMP and a 1987 50 watt 4 hole, which used to be from former whitesnake guitarist Adrian Vandenberg . Modded by Peter van weelden, who did some of Eddie Van Halen’s amps back in the day
I'm not clear on the NFB depth mod, so it's 100K + 220K in series = 320k off the 8R tap, with 470pf across the 220k, which will work a bit differently than replacing the 100k with a 320k with a 470pf across it if you wanted to keep it all on the PCB rather than hanging off the selector. 320K NFB R seems odd, have I got it right? Sounds great BTW.
Ciao JASON , great video , i have a question for you , do you remember the early Bogner xtc what kind of diodes were used for the rectification ? i think 1n53 series but i could be wrong Thanks in advance
Nice! my 2204 jmp has a lower voltage transformer (376VDC after rectification) and it sounds dark compared to the 2203, with the sir34 mod it becomes bright enought but in stock 800 mode it is too dark) is it this common on this series of amps?
Higher value grid stoppers lower the cut off frequency for tube entry low pass filter effects. Actually 33k is the same as a Plexi in the high channel. Two 68k’s in parallel
Hey Jason one quick question.....do you prefer 50 or 100u for your phase inverter (output) filtering and which do you think is better for these modded 2203s?
BTW, I love your vids. I don't know anything at all about electronics, but I dig your passion and willingness to share. Plus all the clips sound KILLER!!
As someone pointed out...sounds still too hairy and fizzy on top. Did you DI this? I really couldn't tell the difference between the changes! Maybe a mic would have communicated the difference(s) better??
@@HeadfirstAmps well, that's the main thing (the end customer). Didn't know if there was a customer on the tail end, or one of yours and just an educational tutorial. Yeah, tone is subjective. A little buzzy still for my taste. I also noted the 470pF on the 100k of V2 was sitting there earlier in the clip from the sequence of changes!! Soo wasn't sure if already included in the tone I was hearing earlier on. Like I said though. I'll listen a third time, but I wasn't hearing a significant difference between clips. Could be the headphones and try a different one or may be the way recorded (DI v. direct mic)?!?? Wasn't hearing it thou. Very subtle.
@@HeadfirstAmps that's right. The change from a cold clipper to standard cathode with bypass will make the most significant difference adding gain, but also hiss and sensitivity. Likewise, tuning the NFB circuit. I'll have to look at your couple caps but did you say you put a 22n on top of 2.2n or in parallel? Changing this and FATening it up can make a significant difference also one way or the other and make playing on certain guitars more or less beneficial and why Friedman puts on a switch to tune to taste n guitar use.
