Rachelle JTM45 Build

Turret Board assembly and mounting

2008-07-31T17:32:00.000-07:00

Here is the front of the board. I used some really cool components thanks to advice from many of the guys on the Metroamp Forums. The signal caps are N.O.S. vintage mustard caps. The electrolytic caps are BC. There's a cool little Lemco ceramic dogbone for the 47pf cap. The dark brown resistors are Allen Bradley N.O.S. I am really psyched to get this amp up and running!

I decided to get the board all wired up. Here is the back of the board wiring. I have not checked it carefully yet so don't copy this!

I wired some of the grounding points on the amp. Keeping everything very neat...

I replaced the carbon film resistors on the input jacks with some carbon composition - they are supposed to have a certain magical mojo when installed in certain parts of the circuit. I am not bucking any trends with this amp. I am using what has been tried and true.

I soldered some of the components onto the turret board. Here it is just placed in the chassis. Man, this is going to be a beauty!

Here is a pic of the stand offs bolted in. I am ready for the board!

I use plenty of loctite and a 1/4" wrench to tighten the standoffs down.

I am getting th chassis ready to install the board. I don't really care for the small stock board mounting hardware so I am using 6-32 .5 inch stainless steel stand offs. Here I am drilling out the chassis for the larger diameter hardware.

Turret Board - Take 2

2008-07-22T16:00:00.000-07:00

Here's the back of the completed board. It's almost a shame to put components in it. Nice...

Awesome! I finished turreting the board and it exceeds my expectations which is a hard thing to do. Ask my bandmates. I see that I am missing a turret on the right side. I will pop that one in later...

Instead of using the other end of the Hoffman turret tool, I used one I got for Watts Tube Audio. Really makes a nice press. Some guys use a drill press to press the turrets, but I tap them with a hammer. I can really feel when they are the correct tightness.

To seat the turrets, I used the base of my drill press again with a Hoffman turret tool screwed into a T-nut hammered in from the back. I used a small parts drawer to keep the board straight. If you don't keep the board straight the turrets can get pressed too much on one side making them less strong and crooked.

Sweet! It came out perfectly. Now I can sleep again...

The holes came out perfectly. I am ready to remove the sticker. I hope it's not like one of those botched plastic surgery movie scenes where the doctor removes the bandages and the patient runs out of the room screaming.

The problem with my bootleg drill press is that I cannot control the speed of the drill when I want to lock it in the on position. I came up with this advanced device to keep the drill rpm slower. A simple cable tie adjusted to pull the trigger to the desired speed. I can slide it off to stop the drill and slide it back on and it would return to the same exact speed. Man, who would you rather be on a desert island with, me or McGyver? I found that a slower speed on the drill helps to make the holes more accurate and cleaner. Press down slowly on the press. Again watch out for the dust - it is an evil red powder. Probably that same stuff in the hour glass the Wicked Witch had in Wizard of Oz.

I wanted to be sure the drill would drop right into the center of the hole. I used a small phillips head screwdriver as a center punch and lightly tapped it with a hammer so the bit would line up better.

I stuck the sticker on. The sticker paper was good because it was not too sticky and I could peel it back to position it exactly.

Now the Turret board is the right size for the template sticker.

I received some new turret board stock from the Metropoulus Amplification store. It was too long so I had to cut it down with a hack saw. I really took my time to make sure the cut was straight. Watch out for that turret board dust! It's like fiber glass and Bondo. If it makes contact with your skin, you will itch like crazy! I wouldn't breathe it either, as I am sure you can do some lung damage. Please wear a mask. The smell made me flashback to when I was doing body work on my '73 Plymouth Satellite Sebring I had in high school. I sanded that thing for months...

I am taking a second stab at drilling my own perf board. I got some sticker paper at Staples that will help hold down the template flat against the turret board material. I printed my Concept Draw document out on a laser printer.

Progress so far...

2008-07-17T10:40:00.000-07:00

Here's my progress so far. I'll get there!

Potentiometer and Input Jack Wiring

2008-07-16T13:19:00.000-07:00

Next I just wired up the input jacks. I soldered the 1M resistors in before putting them in the holes to do the rest.

An extreme close-up of the mustard cap wiring.

Here is another angle of the pot wiring. Heh, Heh, he said pot!

The next thing I figured I could do was wire up the potentiometers. I am trying to get work done that is out of the way from the transformers as I have not received them yet. I am using CTS pots that I got from the Metroamp Store. The backs solder up very easily. I mounted the NOS mustard cap horizontally as I have seen some builders do it. It makes it easy to change if you need to.

Heater Wiring

2008-07-15T11:51:00.000-07:00

I always use stainless steel hardware and stainless locking nuts on all of my builds. I like stuff heavy duty rock and roll just like Spinal Tap.

Here is another angle.

I unwound some of he twisted wire and soldered it to the tube sockets.

I turned the drill very slowly. I have a tendency to twist my heaters too tight so I just took my time.

I am now waiting for new turret board material so I figured I would twist up the heater wires for the tube sockets. I taped together two 18 gauge pieces of PTFE wire and inserted it in the end of my trusty Dewalt cordless drill. I get the PTFE wire from a place called Powerwerx mainly because the name is so kick ass and the wire rules. 18 Gauge is heavier than most people would use but hey, I'm a heavy dude.

Turret Board

2008-07-10T14:30:00.000-07:00

Well, I finished the board but it is not up to my freakishly exacting standards so I am going to try another one. The color is a little too orangey for me anyway, so I think I am just going to use a red swirl color on the next attempt. A slow start...

I supported the board using a parts drawer. Perfect height! I used a hammer and the other end of the Hoffman turret tool to seat the turrets. I have tried using a my drill press but it is a pretty bootleg one and does not work as good a a hammer. Does anything work as good as a hammer?

I am going to press the turrets in anyway just to see how it looks and if I can use the board. I used the base of my drill press to hold the Hoffman turret tool .

Here is the board with the template removed. I tried drilling a little too quickly and it tore the bottom of he board a little bit. I am going to keep going as an experiment.

I am not too happy with my drilling. I have OCD so if something is a little off, it drives me nuts! The template was sliding around too much when I was drilling. Also a bunch of board dust got under the template.

Next I used some packing tape to tape the template to the board material. It seems to be bubbling up in the middle. I am going to try and drill it anyway.

I used a program called Concept Draw to make a template. The hole centers are 3/8" apart

I ordered some brown 10 1/2" by 3 1/8" turret board material from Ken Watts at Turretboards.com. I am going to attempt to drill my own perforated turret board.

Finally getting Started!

2008-07-09T07:29:00.000-07:00

Ok, here we go. I have been doing crazy research for my new build - a JTM45 Marshall clone. What's that you say? I thought Joe Popp swore by the JCM800! Well, the JCM800 is my favorite sound for crunch, but I am expanding my palate of sounds for a new rock musical Pericles that my band The Hornrims is composing music for. Not only do I need a good crunch sound, but I also need a killer clean sound along with a bunch of time based effects.

I admit I was torn but I ended up selling my beloved Rachelle 2204 to build this new amp. I have already built the pedal for getting my crunch sound. I call it the MicroScream and it is a combination of a Ibanez Tube Screamer with Landgraff modifications and an MXR Microamp in one box. The beauty is that it gives me 4 different sounds: Clean, Clean boost, Crunch, Crunch Boosted. Here's the pedal front and back.

Next post I will get to constructing the amp.