Home GuitarPCB Forum GuitarPCB Build Support been down in the dungeon, a-slavin’ away…paramix ???

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    thanks barry!


    Bravo, Jimi!  I well done to you for a  clever project.


    Jimi – Gawd help us all if you ever get into computer coding. LOL! Excellent dive into a successful circuit hack. Thanks for sharing your cool stuff.


    hahaha thanks brothers.

    wilkie… your answer to my initial query made it all possible for my tardfounded arse to figure this out..

    mark, um…. i DO do a bit of coding, tho its been a long time…lol

    the coolest part i think is having the 9v output on the back of the amp tho lol




    so its time to try this again, on a 30 watt pcb someone had pulled years ago… this time, the parallel loop will be for reverb, and i’ll add the series loop for echoes or whatever.

    will report back if it works 😉

    stay tuned!



    My breath is baited (?) waiting for your results. Bravo!

    Big O

    Jimi, you are way braver than I am.  However, I have very little experience working on tube amps other building one with parts and instructions provided -a simple 5W Class A amp head which I named the “One Louder.”  What you did is amazing to me and was quite a project!  I’m still in the KISS mode when it comes to dealing with amps and more complex pedals because I still am primarily the 2nd “S” when it comes to more complex electronic circuitry.


    yo, big o,

    these marshalls are basically a drp stompbox with a transistor power amp ass end.

    believe me, they’re a lot easier to hack on than you may think, and the voltages are mostly not lethal other than the primary.

    here’s vide-o0-no of the beast as it sits now, in process

    part 1

    and part deux. heavy on the “duh”


    well, i gave it the old al bundy try

    won’t work well on this version marshall. it works, but had a hum i couldn’t seem to ditch. so i’ll save it for the back up reverb 12 coming in this week. stay tuned 8)


    This is an object lesson in creative solutions to real world mods that are so clearly (and funnily) explained. It will take some time for me to understand them in their full glory. There’s more learning in there than many electronics textbooks I’ve tried to read, but in truth mostly given up on through my own lack of understanding.

    Hats off to you, oh photonissimo. Many tanks, pun intended


    thanks mybud 😉

    i like buds 😉

    it is a subtly different circuit, AND the paramix i used was the most recent… the older version i used before is laid out a bit differently, and i suspect that may have something to do with it. amps are a bit different from stompboxes, and sometimes what works great for stomps will suck in an amp.

    in this case, it definitely worked… but i couldn’t decouple the power supply adequately, so it was picking up too much line noise.

    couple that with being near a computer, and my cell phone’s interference, in retrospect it’s probably ok… lol. i was on the horn with my son last nite when i figured out the cell phone was making most of the noise happen, even with the top of the amp on and the faraday cage closed.

    it could be too cuz i used MCC’s instead of chicklets like i used last time… its funny, cuz i used up the 220n chicklets that have been in the cap bin for at LEAST a decade now, unused since i discovered the much tighter and more consistant mcc’s, which are also a fraction of the size. i dunno. i’m not done with it all yet. 😉

    the phase invert switch on this one is no where near as subtle…. seems to work on the entire signal rather than just what’s in the loop. having on-board filters helped a little, but not enough. i used a hunk of standoff and made a bipolar power supply, tapping it off the +/- 15v preamp rails with 560r 2 watt resistors and 47uf caps with 3.3nf snubbers to ground to nuke rfi with, and even went so far as to add 22uf caps to the paramix board itself, with the reverse voltage one soldered to pin 11 directly and its positive side to an unused ground pad, and a bipolar 10 uf for the half voltage. it definitely should have worked. but i got too much noise. i thought it was something i did, so i raised the preamp filters from 100uF to 470uF <actually, 430, as i paralleled the stock 100uF’s with 330uF ones> but that had no effect, really.

    this morning, i realized the problem was a combination of the cell phone/computer interference… normally, i’d never have a pc on my bench while working, but now that i have the capability of net in my dungeon, well… it gets boring down there at 3 am when you’re monkeying and wired on ‘fiene and doobage lol…

    so…. how to fix? easy, in it’s way… the guts of the marshall 5010 78-2 circuit <the rare “red box” one that previously had no schematic for, but thanks to TassieViking on SSguitar forum now exists from my pics and bom and measurements, attached>
    are all 1/2 watt cc resistors. cc’s sound great, but carbon likes to absorb moisture, and they can make serious frying bacon noises happen, which was a good part of the problem. so when i get my next parts order from tayda, i’ll make sure i buy proper values in metal film resistors and re-build the entire amp with them instead of the carbon comps. that should nuke the noise/hum/hiss just about completely, judging from prior experiments with these suckers.

    so…. tho defeated in the moment, i have not yet begun to fight 😉

    stay tuned… i got another marshall reverb 12 coming this week, and that’s getting the loop added like the other one… if the circuit is the same, anyways…


    rock on



Viewing 12 posts - 18 through 29 (of 29 total)
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