# Let's clone a Marshall



## Jimmy_D (Jul 4, 2009)

Over the years a few Marshalls have gone through my house and I never really found one that does the "Marshall" thing well enough to make it stand out, and make it a keeper. 

I know about all the clones out there that do the job, but faced with the imagined need for a nice Marshall and the usual decision of not wanting to pay large for the real thing, or even more for one of the big name knock offs, I decided to make one for myself. This is a head version and I actually finished it up on Xmas eve and gave it to myself, I took a bunch of pics so I'll try to lay out this thread in a way that someone who wants to build one might find helpful... and this time the thread will end with sound clips.

A week of nights cruising the net looking at schematics and layouts, reading opinions on different models on forums, and I had assembled a set of drawings and made a parts list for what I figured would work best for me - a JCM800 master volume 50watt, more or less following this schematic (from Robinette.com), in a Hammond 16" aluminum chassis (which is easy to machine especially when you can drill everything, no PT cutout req'd like a Fender).










I ordered everything I could from NextGen, the balance of the parts came from Digikey and Sayal. Both transformers and the choke are Hammond which I think are quality products and great for the task. Marshall replacement transformers for this model are; power - 290GX, output -1750N, 5H choke - 194F they give you everything you need and no extra wires, all colours match original Marshall spec's so layouts are easy to read for wire location.

For the board I usually figure out what if any mods are being incorporated (in this case only a neg feedback switch to go between 50watt neg feedback levels - 100k, and 100watt neg feedback levels - 56k), and how the board will fit into the chassis, then layout my board and go - of course borrowing as much as makes sense from existing layouts used by Marshall and all the others.

I know it's not a Marshall thing but I chose eyelets on fiberboard instead of turrets on something harder, as to me they require the least work and still make a quality product that's easy to service. ps. I've found almost anything can be made into a staking tool for those eyelets.




















Getting there










Board just washed with flux cleaner and ready to install, leaving as usual, leads far too long.











More to follow


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## SG-Rocker (Dec 30, 2007)

Lookin' good. I built 2204 into a 5010 combo amp earlier this year and also used Hammond xformers and choke. Dimensionally, they are the same as the Drakes in my '83 2204 CSA and sound amazing. With a Neo Creamback, it makes a lethal grab and go amp that has turned a few heads.


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## Jimmy_D (Jul 4, 2009)

Hammond chassis drilled and and ready to go, this chassis is smaller than the Marshall version but there's still plenty of space - you could dwell on it but just place everything where it makes sense.





















Transformers and sockets mounted











Almost ready for the board


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## WCGill (Mar 27, 2009)

Damn, that bench is a holy mess, just like mine used to look.


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## Jimmy_D (Jul 4, 2009)

In goes the board, which hopefully with some planning is easy.










Start hooking up wires including the shielded inputs to V1 which I made with regular braided shielded cloth wire and heat shrink tubing, and the twisted AC heater wires.











This power transformer weights a ton and the output is also pretty heavy and almost in the middle of the aluminum chassis, which really can't handle that load, so you can see I used a couple standoffs / nuts / 8-32 machine screws to make a pair legs adjusted flush with the underside of the chassis, to support one side of the power transformer and hopefully help carry the output transformer.












Bottom left is the only "option" - 3 way negative feedback switching using a Carling on/off/on, switching between levels of neg feedback for both 50 watt (100K) and 100watt (56K) models - both of which feed the 4ohm tap (which I won't be using I'm only switching between 8 and 16 ohms) - and a centre option of no neg feedback (which has questionable usability but comes free when you can't find suitable on/on switch)










No, I didn't lose the bright cap per internet opinions, I can cut it out any time.













.


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## Jimmy_D (Jul 4, 2009)

WCGill said:


> Damn, that bench is a holy mess, just like mine used to look.


Lol... I sat back the other day and noticing I was getting tight for space, and what a joke my bench was, I promised myself I'd clean up and organize soon, then I shot these.

(see what I meant about leaving too much length on the board leads, I can't throw it out... still have to gather it.


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## jb welder (Sep 14, 2010)

That's better. The less bench showing, the more you're trying. 

I'm with you as far as preferring eyelet to turrets.
Nice work.


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## Rhyswatsonto (Dec 6, 2020)

Jimmy_D said:


> Lol... I sat back the other day and noticing I was getting tight for space, and what a joke my bench was, I promised myself I'd clean up and organize soon, then I shot these.
> 
> (see what I meant about leaving too much length on the board leads, I can't throw it out... still have to gather it.
> 
> ...


That work bench looks awesome man! I’ve bought a few used clones off of people and they always sound amazing.. I was thinking of making one myself until I saw this haha. This looks way out of my league.. but maybe super rewarding.


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## Jimmy_D (Jul 4, 2009)

I can't figure out right now where my last set of pics are, once I finished it up and got it ready to go into the cabinet, so I'm going to have to come back and edit those in here
.
But it's pretty self explanatory, follow all your leads and all the golden rules and you should be fine. I do check all caps and resistors before installing, I'm using 5% tolerance unless I can't find them, I buy extras and try to find ones for use as close as possible to the spec called for on the drawing. Check and double check your work, hopefully using a meter!

About the cabinet -

Other than my control layout I had no concerns about making it look like an actual Marshall cabinet, so made it a couple inches taller than it needed to be as there is some heat that comes from the back, not from the transformers but those power tubes generate heat.

To make my life easier and because I have access to one this cabinet is pretty much right off a CNC with very little hand work before assembly, it's a finger jointed 3/4" Russian Birch ply box with a face plate, but it's a box so you can make one that'll do the job pretty easily any number of ways.

All I can say about tolex work is that it's a pain and it's actually a bit nerve-wracking as you get closer to being done, worrying about not butchering the last corner once you've already piled that work into it. I use regular solvent based spray contact cement, an upholstery tacker and go at it. There's plenty of info out there on different methods and techniques but if it's your first time, just buy some extra material watch some videos and do some test pieces to get the hang of it.

The faceplate is something I could have spent more time on but this one's for me so I can live with it. No doubt with some time I could do a much better job but essentially what you're looking at is - a piece of 1/16" phenolic, sprayed with gold nitro on a white primer, with waterslide decals right off my printer for typeface, and a couple clear top coats to seal it all in. With the aid of a hair dryer and with no time left to get this done before Xmas, I made this faceplate in a few hours, spending little to no time on the "artwork" and floating everything into place by eye - if you made more of an effort you could make a very nice job of using this method.

Note; unfortunately and as you can see, while the Nextgen purple tolex looks killer by itself, especially with their gold piping and handle, it almost tragically clashes with my purple celluloid (I'm still lol about this one) speaker cabinet - so it's going to have to reside elsewhere in my music room, which wasn't my plan at all, anyway here it is.

Cabinet and faceplate finished on the bench










In the kitchen for a wash up before installing the goodies.










Amp installed in cabinet, btw this one worked perfectly right off the bench, it runs quietly and so far everything is perfect, so double and triple checking your work pays off!










Sound clips coming up...


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## Jimmy_D (Jul 4, 2009)

Okay here we go, I took this head to my sons house as he's all set up to record, he recorded these sample through an Orange 212 cabinet with V30's and while it's a whole separate thread, I'd like to note this amp sounds way different through my 410 with Celestion golds, in a good way.

Cleans, which to me sound pretty much like Fender cleans (especially with reverb added) and not what I want this amp for, but let's start here because it sounds pretty good to me - New American Pro 2 Strat with V Mod pups and digital reverb


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https://soundcloud.com/user-506517611%2Fstrat-1


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https://soundcloud.com/user-506517611%2Fstrat-2

Overdrive - more of what I was looking for - one of my Double Burstbucker Maple and Mahogany semi hollows 


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https://soundcloud.com/user-506517611%2Fhumbuckers-1


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https://soundcloud.com/user-506517611%2Fhumbuckers-2


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https://soundcloud.com/user-506517611%2Fhumbuckers-3


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## Jimmy_D (Jul 4, 2009)

A bit more overdrive (volume), my 1981 Greco EG LP with stock pups and replacement electrics, adding a bit of a boost with a Prince of Tone (single KOT) clone I made a while back (and yes I paid for the unobtainium diodes) and a shot of the innards said clone.


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https://soundcloud.com/user-506517611%2Fbucker-4


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## sambonee (Dec 20, 2007)

Jim, happy new year. well I never made it up to your shop, sorry man. I really wanted to. When I saw that you were going to build an amp I had a hunch that it was going to be amazing like your other work. that gold Greco bass is still haunting me! 

your sound clips are sweet. I'm curious as to which pickup position they were done it. my ear tells me that it was the same position all throughout. I also noticed that there was no muddiness anywhere. you did a great job. and Purple is my fav, color. 

Keep up the awesome work man. you've got the knack!! 

all the way from Spain!!


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## aC2rs (Jul 9, 2007)

Excellent thread for an awesome build!
Your amp looks and sounds great!


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## laristotle (Aug 29, 2019)

sambonee said:


> that gold Greco bass is still haunting me!


Me too. lol


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## Mikev7305 (Jan 6, 2020)

Great thread Jim. The amp looks and sounds fantastic. I love how you waited until you were complete to post all this. To see an amp go from parts to completion including sound clips in one quick read is a great way to do it. Well done!


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## nonreverb (Sep 19, 2006)

Jimmy_D said:


> Lol... I sat back the other day and noticing I was getting tight for space, and what a joke my bench was, I promised myself I'd clean up and organize soon, then I shot these.
> 
> (see what I meant about leaving too much length on the board leads, I can't throw it out... still have to gather it.
> 
> ...


That workbench makes me feel at home. 
Great work!


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## bzrkrage (Mar 20, 2011)

@Jimmy_D , brilliant work. The humbucker2 clip is great. Look forward to the 410 clips. (Maybe matching tolex for that cabinet?)


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