Turret Boards

I originally ordered a turret board for a JTM45 thinking I was going to build a 50 watt amp, but after some thought I decided to go for a 100 watt. The original circuit board I got was a gorgeous super dark brown with split turrets. After deciding to go for the 100 watt, I would need another board required for the filter caps and rectifier. As hard as I tried I could not find any circuit board material that would match dark brown. I could go with a mismatched board, but anybody that has read of my maniacal O.C.D. on these pages knows that is not going to happen.

I decided instead of beating my head against the wall to find a match, I would order a new red swirl board set of both boards from Valvestorm. My issue with this board set is that the turrets are the thin walled variety and not what I was looking to use on this build. I had my heart set on those snazzy split top turrets.

I went ahead and drilled out all of the existing turrets and replaced them with the spilt tops that I purchased from Watts Tube Audio a while back. The difficulty with split top turrets is that the split needs to be lined up vertically. This is difficult to do since you stake them in with a hammer and special anvil so they have a tendency to spin. I came up with a technique where I seated the turret first with a few blows of the hammer, then I would spin the turrets and give them a final seating. This is very time consuming and I will never do it again – straight ahead round top turrets for me next time!

They do look awfully cool though…

Socket Install and Heater Wiring

Time to get to wiring this beast! I found some very sweet Clinch 9-pin Bakelite preamp tube sockets on eBay. I am not sure about the mojo of the Bakelite material but purists swear they can hear the difference. Who am I to question the prevailing opinion? I bolted them in with 1/4″ 4-40 stainless machine screws with Nyloc nuts I sourced from Bolt Depot. For the power tube sockets, I purchased the Amphenol 8-pin sockets from Valvestorm, also made of similar phenolic material as the preamp sockets. I bolted these in with 1/4″ 6-32 stainless machine screws with Nyloc nuts as well. On the screw closest to the back panel, I also included a grounding lug that will be used for the 1 ohm resistor and connected to pins 1 and 8 on the power tune sockets utilized for biasing the amp.

I wired the heaters using 18AWG PTFE wire that I got from my main man Scott from Apex Jr. His prices are unbeatable, as is his personal service. He’s not afraid to pick up the phone or clarify an order, a sadly diminishing practice these days. Instead of using a drill to twist the heaters, I did them by hand because the are pretty short and I also did ant to wrestle with un-twisting the leads that go to the tube sockets.

The black wires connect pins 9 on the preamp sockets to pins 7 on the power tube sockets. The red wires connect pins 4 and 5 on the preamp sockets to the pins 2 on the power tube sockets.

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Amp Plate back from BNP Lasers

I sent the amp plate artwork off to BNP Lasers and I got it back in record time. Again, I can’t say enough about BNP Lasers. Jeanne Kangas treats even my smallest order with the utmost of care. She even questioned if my on/off switch was too close to the the logo just to be sure I was getting what I wanted. I assured her it was close but correct. Service like BNP provides is rare in this day and age and much appreciated by ham-and-eggers like myself.

The plate came out stellar!

Amp Plate Adjustments

My original amp plate design needed some adjustments. I actually had to make it wider and move some of the graphics around. I decided to not use the plexi-style switch rings and just opted for the thinner knurled type so square Joe Popp logo would have more room. I am such a nut because I can see the difference a 1/32″ makes. But I don’t mind putting in the time because this is a keeper amp and it needs to be perfect. I will twist and turn in my bed and never sleep if it is not! Since the print out is longer than a sheet of paper even in landscape mode, I had to print the face plate test using the overlap function in Adobe Illustrator CS5. It’s looking just the way I want it after many hours of tweaking.

Popp Block Logos

I waffle back and fourth on the idea of putting Marshall logos on my amps. They are not Marshall amps after all, but my own versions. I decided I would get my best friend, graphic artist, drummer, and The Rock File author, Tylor Durand to design some logo plates based on the classic Marshall block logo. I had a knock off copy of the logo and scanned it for him to replicate. After a few tweaks and some back and forth, he really nailed the design! I like it because not only does it have my name on it, but is also an homage to the Marshall amplifiers I know and love.

Head Cabinet

I wanted to get the amp plate just right so I went ahead and ordered a large head cabinet from Valvestorm. These are built by Mojo Tone (another awesome company) but the great thing about sourcing them from Valvestorm is that they have them in stock whereas Mojo builds to order. Now that I have the chassis and the head cabinet I can be sure that everything about my front amp plate design is perfect.

Large 100 Watt Head Cabinet

Large 100 Watt Head Cabinet

Amp Plate Design – Yes, it goes to 11.

I am doing a custom front amp plate. There are 4 inputs so things are a little tighter for the graphics. I used Adobe Illustrator CS5 to create the artwork. I actually used the design from my JCM800 Combo and edited as needed. This saved me a lot of time especially when lining things up.

I am going to use a stock back plate from Valvestorm because the chassis is 25 1/4″ inches wide and BNP Lasers can’t do Alumamark past 24 inches. I am not sure yet if I am going to do the external bias control and test points as that will add time to the build.

Front plate design

Front plate design

Let’s begin

I had a bunch of parts leftover from some other builds and I figured I would slap together a JTM45 clone to use as a clean amp. I have the crunch covered with my last build, a JCM800 combo I constructed after a 5 year hiatus from amp building. But after thinking the project through, I thought I would up the ante and construct a Marshall JTM45/100 100 watt Dickinson spec clone. I’ve never built a 100 watt amp before and after a bunch of research the JTM45/100 Dickinson spec became the obvious choice. This is referred to as the “Hendrix Amp” although Hendrix used a variety of amps including Fenders. My first step was to get a chassis and see what I would be dealing with. I went to the Valvestorm website, my go to place for parts,  and ordered a beautifully constructed aluminum chassis. I also got a stock rear amp plate as I was only going to do a custom job for the front panel.

Here we go!