Category Archives: Parts

Neutrik powerCON Connector

I haven’t had much tome to work on the amp but I am getting back to it! Instead of using a I.E.C. power cable that can be stepped on and yanked out, I am employing a Neutrik powerCON series connector. This is a locking connector that can take heavy gauge cable. I used a step bit to drill out the hole to accept the fatter body of the Neutrik.

 

Really Cool Parts

Part of the fun for me when building an amp is hunting down cool parts. I try to find as many vintage parts as I can, but then I combine these with some modern items for dependability and functionality. I have scored some holy grail parts already but I still need to fill in some gaps. There is a certain mystique associated with vintage parts. Amp builders call it “mojo.” While the older parts often pale in comparison spec-wise and noise-wise to modern parts, builders use them to come as close as they can to the original tone and dare I say soul of the original Plexi and JTM45 amplifiers. The parts are expensive but my idea is to build this amp once and it will be the last amp I ever own. Here are some of the parts I have acquired:

1970s Mullard “Mustard” Capacitors – These are a must when seeking the tone, feel and look of a vintage Marshall amp. I found these N.O.S. (New Old Stock) on eBay from a seller in Greece. I still need to find a .68uF 160 volt which is pretty tough to do. They look like mustard from a squeeze bottle, hence the name.

Radiospares 560pF Capacitors – I had one of these already that I bought a long time ago, but I need 2 for the build. One is for the bright channel mix capacitor and the other for treble tone stack. I found one from a seller in France on the Metroamp Forum. paid a bunch. Ouch.

Carling Switches with Plexi-style Chrome Toggle Rings – These were both readily available on the Valvestorm.com site, a very cool place to find Marshall parts.

Piher Resistors – These are the same brand of resistors used in Marshall JMP and JCM800 amps of the late 70’s and early 80’s. I sourced them from guys in France and Spain. The 1/2 watt ones I found are from the 60s and 70s while the 2 watters are 90s vintage. I am still missing 2K7 and 4K7 values in 1/2 watt. The hunt continues…

Lemco Dogbone 47pF – This will be the phase inverter capacitor. Valvestorm.com

BC 10uF 160 volt – I found some 400 volt versions on eBay.uk that I was going to use but then I stumbled on the proper 160 volt versions at Valvestorm. These will be in the bias capacitor positions.

Belling Lee Fuse Holders – Very cool N.O.S. fuse holders I found on eBay from a guy in Pulborough, England.

ARS Dual Can Capacitors – These beauties will serve as the filter capacitors. When filter caps sit for a while they need to be reformed. These are sold reformed from Valvestorm.com.

1K 7watt Welwyn W22 Wirewound Resistors – These will live in the screen resistor position on each power tube socket. Very cool classic resistors from Valvestorm.

Metroamp 50 Watt Plexi chassis – This build is being done on a standard 50 watt Plexi chassis. The original JCM800 amplifiers had a much longer chassis. I want to keep the build compact so I am going with a the smaller chassis. On my previous JCM800 amps I used this same sized chassis as well. Once again – Valvestorm.com.

Paxolin Circuit Board Material

I am going to get pretty crazy about parts for this amp. I have O.C.D. and when I make things they must be exactly what I want. I have been on the Metroamp forum since I started building amps and there always seems to be somebody selling cool parts. I was shopping around for circuit board material and found a forum member that had a stack of brown Paxolin circuit board material that he was selling for cheap. He ordered a bunch from England and didn’t need the rest. I ended up getting 8 sheets for $30 shipped which is an amazing deal. My clone starts it’s life with the perfect circuit board material from the motherland of Marshall Amplification.

jcm800_007

Combo Cabinet for the JCM800

My goal is to make a very compact Marshall JCM800 clone, one that I can be easily transported to NYC rock clubs if need be. I used to have a head and a 2-12 cabinet but that is just too big to deal with in the city. A while back I built a JTM45 and later converted it to a combo. I had expert cabinet builder Jeff Swanson make a 20″ wide 1-12 cabinet that a 17″ JTM45 chassis could be crowbarred into. It was a great little combo amp, loud, clean, and compact. But I didn’t end up using the amp much, since I always rehearse at Smash Studios that has amps available. Most gigs I play have a backline as well so I wouldn’t carry the amp with me at all. A zydeco fiddle player named Jonno Frishberg tripped onto my amp pages and made me an offer for the JTM. I wanted to keep the cabinet as it was pretty expensive and totally custom, but Jonno ended up buying the chassis from me. He loves the amp and sent me a bunch of pictures of it at festivals and shows. He even made a name plate with my name on it for the head cabinet. I stored the combo cabinet for a couple of years knowing that the day would come where I would build the ultimate JCM800 Combo. Today I begin. Below are some of the pics of the cabinet I use for the amp.