Completed First TW Express build

[casey73]

Just finished my first TW Express (slightly modified) build last night. Thanks to all here who answered my questions regarding this build. I put pics up on the Trainwreck files forum. I made several deviations from the original Express, but it still sounds great. I set the volume down on my neck PU and wide open on the bridge PU, and did the back and forth thing like Glen Kuykendall does for his Express demo on youtube. I was playing my Ibanez ARX320 with Tonerider Alnico II Classic humbuckers.

This project started about a year ago. I got a nice heavy 14 gauge aluminum chassis (17 x 8 x 2) on Ebay from Dirty Dawg Amps. Then I picked up a Pacific Transformers TF-125 (Bassman replacement w/2-4-8 ohm taps) and a Hammond 290LX (drop in replacement for JTM45) both new in box for a song at a guitar show last April. Originally I was going to do a JTM45, but decided on the Express instead. I've got JJ 6L6's in it right now. I can put EL34's in it, but the OT primary is 4.2K, so it likely won't sound like they would with a 6K primary.

At the same guitar show I picked up a nice turret board, several new JJ multi-section caps, some IEC power sockets. I removed several turrets and installed several to match the Express board layout. I used a 3mm orange/red LED in a black bezel for the pilot, running it off the unused 5 volt filament tap. For the faceplate I had to improvise. Because the chassis is thicker than the original TW chassis, I got a piece of galvanized sheet metal, cut it to size and then laminated some mahogany veneer to it using contact cement. I stained the mahogany with dark walnut stain and put on two light coats of matte finish clear coat.

I had many of the parts in my shop inventory with the exception of a few pots and small caps. I fabricated the power/bias supply from some FR4 I got years ago using turrets. I had two 2K 10W resistors that I paralleled for the 25W in the original, used two 1N5408 rectifiers instead of the multiple 1N4007s, and mounted the bias pot (75K - 10 turn) on the back panel with test points. I'll need to change the 47K resistor in the bias supply to get more range out of the bias adjustment as I can't get more than -39 volts out of it so the 6L6's are running close to max dissipation. I did not install the power spike protections diodes.

I followed the A1a version schematic combined with the Ceriatone layout (47pf across phase inverter plates) but no input grid stopper. I also used the Thunderfunk TW layout and utilized the poly/ceramic combo for the .002 coupling cap after the second gain stage. And I used only one output jack with an impedance selector.

I finished late last night, so only played a little and not real loud (through a Jensen C12K in an old Carvin 1-12 cab. My garage is insulated but the neighbors can still hear me, so I'll wait till later today the give it a real workout.

Initial impressions are, it has tons of gain. I had to scrounge through my tube box to get 3 - 12AX7's (a Sovtek WXT, U.S. Phillips JAN and a EH).
I never turned the volume past 10 o'clock last night. Crazy controlled sustain feedback a low levels. I don't think the bright switch is necessary as it is pretty bright without it. I'm going to plug in a 12AY7 and 5751 into the first two slots today and see if tames it a little, but adjusting the bias may help as it is running on the hot side. Very low hum, but some hiss (not objectionable) as to be expected with this set up.

Now I just have to build a cabinet for it. I'll report back when I've tweaked it a bit. Overall, I'm please with the results.

[BIG Dave]

Congratulations! Post some pics!

[casey73]

Congratulations! Post some pics!

I post them on the Trainwreck Files forum.