At the end of this step we should, in theory, have a working amplifier. The step mainly involves straight one-to-one wiring of the main-board leads to the pots and tube sockets, as well as wiring the power supply leads to the appropriate main-board turrets.

This photo shows the final wiring, after I upgraded the yellow Mallory 150s supplied in the kit to Orange-Drop 600V polyester capacitors. I found the 150s bright/brittle sounding and noticed in my tweaking that they are quite microphonic as well. The orange drops should be the 6PS type from Vishay/Sprague or SBE or the PVC type from Mallory. You don’t want the 715 series polyproplyene capacitors.

You might also notice a grid resistor on the 2nd triode of V1. In my debugging I had played with a grid resistor here to help stabilize the amplifier a bit (keep it from easily breaking into oscillation). A grid resistor is a common tweak seen in real Trainwrecks as well, a common result of the tweaking process. I don’t think I need this resistor anymore, but felt it did no harm to leave it in place.

Another, earlier, overview shot of the main-board wired in place. Definitely refer back to the Francesca wiring pictures for this phase of the project (see Part 1)! You want to make sure that you get the lead dress (wire routing and shaping) correct here!

After completing all the amp wiring, check and double-check the finished product against your layout diagrams and wiring photos. It may help to take a break from the project and come back to do your final checks with fresh eyes. Resist rushing to plug it in and ’smoke test’ the device… you might get smoke! Next time we’ll talk about power up and debugging.

Some of the most critical wiring in a high-gain amp like the Trainwreck is around the 1st tube stage… including the Input Jack, the Volume Control, and the route to the grid of the 2nd stage triode. In my project I found the placement of the bright caps and damping microphonics associated with them to be a challenge. The lead dress in this area, including the ground wire and the blue wire leading from the volume control is very critical and I tacked the wires and caps in place with hot glue at several points on the chassis.

It is very convenient to pre-wire all the pots and get the ground-bus established before fitting in the main board. One of the hardest things was to get a good reliable connection from the back of each pot to the brass rod provided as a ground bus. The brass rod takes solder well, but the pot cases are another story. I filed the pot cases to roughen the surface and take off any lacquer, but I think you also need a really powerful heavy-tipped soldering iron to get enough heat to take solder well. If you have pots with stainless steel cases (like mil-spec clarostat or PEC) you wouldn’t be able to solder at all and you’d need to find special lug rings that go over each pot shaft to make the chassis ground connection. Separate wires go from the pot connections to the ground bus as required. The yellow wire is the negative feed-back to the presence pot circuit from the 8-ohm speaker lug on the impedance selector switch (see other posting).

The coax lead from the input Jack to the grid of the 1st amplifier stage has its shield grounded right at the jack and left open at the grid to avoid a ground loop and potential noise from that.

In the overview picture we see the chassis now complete except for the main board.

The trickiest part of this project is probably the installation of the power supply board and the filter capacitors. Careful consideration must be given to terminating the various grounds and some care in routing the DC voltages as well. The published layouts provide a good guide and hopefully the high resolution versions of these pictures (click on the picture) will help some more.

I used a hot-glue gun to bond the capacitors together and attach them to the chassis. Others swear that you have to use silicone and worry that the chassis interior may get hot enough to melt or at least soften the hot-glue.

One of the changes I made was to short the bias wiper to the unused leg of the potentiometer in order to ensure that an intermittent wiper wouldn’t open circuit the bias pot completely.

Mounting Components and Wiring the Power Tube Sockets

You were half finished when you hooked up the output transformer and heater wires. The remainder of the power tube wiring is straight forward.

A spare tube pin is used to mount the screen resistor and the screen supply, direct from the power board, is daisy-chained to that pin on both power tube sockets.

I found a couple of precision 1-ohm resistors in my kit so I wired up the cathode and suppressor to ground on each tube through a 1-ohm resistor that is useful for checking and setting the bias.

The little stack of diodes is used to protect against fly-back voltages and supposedly keep a shorted tube from taking out the output transformer… a safety modification Ken used to do in his repair business.

The grid resistors are mounted ‘flying’ off of the grid pin on the tube socket… keep grid resistors close to the pin. The purple wires shown above are the two phased output from the PI tube. Keep the two PI wires symmetrical at the tube so that you can easily swap them if you get positive feedback (squealing) when you first power up. There is a 50% chance of feedback because apparently the transformers aren’t wired with the phase consistent.

Sorry, but any comments that have been posted in the last day or so are lost since I was working with a backup copy of the site on the new host.

Please use the ‘Contact Me’ page if you notice anything amiss.

Thanks, -mark.

On the occasion of what would have been Ken Fisher’s 63rd birthday (May 12, 2008), Geetarpicker (Glen Kuykendall) has released a new YouTube video that features his original Trainwreck and a newly acquired Strat… (maybe I’ve scooped Stratoblogster with this one!)

This is an awesome example of what can be done with the Express. A couple of things to note: tone-wise, everything is accomplished with just the volume knob on the guitar, and Glen is playing with heavy looking earplugs installed! These amps are loud!

Happy Birthday, Ken!

Glen has put together an album of tracks, including this one, all recorded using his Trainwreck. It is available at a very reasonable price on eBay:

Glen Kuykendall CD featuringTrainwreck Recordings

World’s Most Ridiculous Guitar Blog! Ridiculous new guitar products, ridiculously hot new guitar players, links to the best eBay guitar gear suppliers online and Strat-o-Sisters who play guitar so hot, it’s just ridiculous!

I first stumbled onto JP’s blog when he posted about an excellent NPR interview with Robin Trower: Robin Trower Interview on NPR! Holy S#$*!!!

I keep going back for the ridiculous tongue-in-cheek commentary, I never fail to be surprised at where he can find Strats.

ps Just had to try out this new Windows Live Writer software with something!

I think that with the addition of Mr. Worley’s document we can assert that the Franscesca Trainwreck Express is the most well documented DIY project on AmpGarage.

The Builder’s Guide talks about using Ceriatone kits and Allynmey chassis and also dwells on the extra effort required to make a DIY Express a faithful clone of the original. I strongly recommend you download the Guide as it will offer much more information then my own scribblings in this series of posts… here I am only trying to capture some of the major steps and document mis-steps that I ran across in particular.

I’m posting this right away to bring it to your attention quickly and in the next post I’ll resume with the construction details of my Express build…

With the latest contributions you have a really good set of reference materials if you want to make your clone close to the original… starting with the composite photograph of Francesca’s layout, a clean schematic and finally a checked-out layout diagram.

Mechanical mounting of components

The next phase of the Expression project is to do all the mechanical mounting, with the exception of the turret boards, and wire the AC… power cord, fuse, switches, pilot light, transformers, speaker connectors and OT primary connections to the power tubes. We will also dry-fit the turret boards to make sure that all the mounting studs are positioned properly… I had a minor problem with one of the power-supply board mounting studs in my build and had to use the tolerances of all the other studs to accomodate the slight hole alignment problem.

All screws and nuts (or stand-offs in place of nuts) should have lock washers on the nut side… there will be a lot of vibration as part of normal operation of the amplifier and you don’t want something coming loose in an inaccessible location of the chassis after assembly. The transformers are mounted with washers under the screw head to ensure ample coverage of the slotted transformer mounting tabs and locking nuts for security. The potentiometers need the internal nut adjusted for the correct thread depth to accomodate the lock-washer, chassis thickness, faceplate thickness and exterior nut.

Power Transformer and AC Wiring

When mounting the transformers, make sure that plastic grommets are installed into the holes to route the transformer leads through. The power transformer is mounted so that the secondary wires come out the inner-most grommet in the chassis.

I got the following information from Nik on the Power Transformer:
Primary:

• 0 (neutral) = black
• 120VAC = orange
• 100VAC = blue (Japan)
• Shield = Green stripe (grounded to chassis)

Secondary:

• 3.15V - brown
• 0 - grey (Filament CT, ground this one)
• 3.15 - brown

• 290V - purple, rated at 150mA per side (300mA)
• 260 - white (for liverpool)
• 0 - grey (HT CT, grounded)
• 260 - white (for liverpool)
• 290 - purple

• 5 Yellow (not used)
• 0 Yellow (not used)

Pairs of wires should be tightly and evenly twisted together to minimize the potential of hum. In the case of the power transformer, the yellows, whites and purples on the secondary are twisted together and the browns from the primary wiring side are twisted together. Yellows and whites aren’t used… any unused wires should be taped (or heat-shrink on the ends of the wires), coiled and stowed out of the way. I created coils that would fit under the power supply board for the unused secondary wires and a tight coil for the unused primary tap.

Speaking of the primary tap, I experienced a problem with the voltages on my build which I believe was due to a transformer wiring mixup that Nik had told me about via email… my voltages were all too high in the power supply. The ratio was 120/100, suggesting a mixup in the colours for the primary taps… I ended up switching to the blue wire (different from these build photos) which was supposed to be the 100V tap but turned out to be the 120V tap. I spent a week or so fighting microphonic tubes and stability/oscillation problems because I didn’t check the voltages against a known Trainwreck and had assumed that the voltages would be correct by design!

When wiriing the AC from the power cord input it is best to take the safety ground wire directly to its own chassis ground stud with a ring-terminal so that it can’t slip off inadvertantly. The hot wire should be short and go to the back of the fuse holder for additional safety when the fuse is out. A twisted pair can then be made of the fused hot wire and the neutral wire from the power cord and routed up to the front of the chassis where hot and neutral each have a pole on the power switch.

It is traditional to have a MOV (surge varistor) across the AC line at the power switch. I used a special non-shorting capacitor in my build to help surpress any RFI from the line.

Heater AC Wiring

The brown pair from the transformer is routed to the first power tube heater connections and then the heaters for all the other tubes are daisy-chained together from there. I like to ensure that the phase of the heater wires is kept the same on each tube they connect to, but that is subject to varying opinions. In the early build photos there was an error in linking the last power tube to the phase inverter preamp tube… the heater wires were put on the wrong side of the PI tube socket where they would’ve potentially interferred with the PI signals. I’ve included a picture from later in the assembly process to show you the correct orientation of the heater wires… but you already have that figured out from studying the Francesa photos, right?

Output Transformer and Speaker Jack Wiring

The Output Transformer wiring is pretty straight forward. Make sure you align the transformer so that the secondary wires come out near the speaker impedance selector switch as shown. I had a dialogue with Nik to get the transformer colour code and impedances:

• Pink = AN 1 (6.6K-ohm for express)
• Blue = AN 2 (5.2K-ohm for liverpool)
• Red = CT (Center Tap)
• Brown = AN 2 (5.2K for liverpool)
• Grey = AN 1 (6.6K for express)

OT Secondary: (bundle all the wires together with zip-ties, no twisting of the pairs)

• Black =0; routed directly to the speaker jacks and also grounded to the chassis at a power tube socket.
• Green = 4
• Yellow = 8-ohm; later the negative feedback wire will come from the yellow connection on the speaker impedance selector and be routed to the presence potentiometer.
• Orange = 16

I twisted the Pink & Blue together and routed them to one power tube socket (connecting the Pink) and I separately twisted Grey & Brown together and routed them to the other power tube socket, connecting Grey.

Future Considerations

As you complete the preliminary assembly and wiring keep in mind that you will likely want to add a wooden faceplate to the ‘wreck in the future (for tradition’s sake!). This can be a problem with the pilot lamp in particular… the lamp installs from the outside and the nut is internal to the chassis… you need to plan wiring so that you still have room to tighten/loosen the nut and if the pilot light doesn’t slip apart you may need to unsolder the wires and reconnect them once the new faceplate is substituted. If you build without a faceplate you have to plan for the switches and pots to have enough thread depth from the internal lock-nut to accomodate the thickness of the faceplate, nut and washer on the outside. You will also note that the input jack cannot be tightened up properly as it needs a minimum thickness of material in the faceplate. Moot points if you already have your wooden face plate at the start of the project or plan to stick with the plastic one that Ceriatone provides.

Next time we will work on wiring up the power supply board filter capacitors and the power tubes…

ReValver™ MK III

Peavey ReValver™ MK III models 15 of the world’s most popular guitar amplifiers, including models of Peavey 6505®, JSX®, Classic®, ValveKing® and Triple XXX® amps, through an exclusive algorithm that analyzes the interactions of the components on the circuit level, based on the amps’ original schematics. By controlling these amplifier models from the component level, ReValver is able to model every nuance with amazing accuracy. ReValver MK III also features a robust stomp-box and effects section including various types of chorus, distortion, wah, tremolo, compression, limiter, delay, octaver and much more. A new FFT-based convolution reverb allows for very complex and smooth reverbs, including sampled spring reverb.

• 15 amp models, including Peavey 6505®, JSX®, Classic®, ValveKing® and Triple XXX®
• 12 Preamplifiers
• 9 Power Amplifiers
• 19 Stompboxes
• 11 Effects
• More than 150 speaker simulations using real-time convolution and membrane modeling
• 7 Utility Functions including tuners, analyzer, splitters, and more
• Fully MIDI mappable
• Tuner
• VST, AU compatible
• ASIO/WDM, CoreAudio
• Standalone or Plugin

But what’s most interesting to me is what is implied by the ‘tweak’ features in the Mk III version of the product.  I’m not sure whether you get to change the amplifier topology or if you have to work with fixed versions… but there is some flexibility implied in the choice of preamps/poweramps, etc. and the tube-stage tweaking interface (shown below) looks like it has enough flexibility to prototype a tube amp…  check out the Musician’s Friend product listing:
Peavey ReValver MK III Amp Modeling Software Plug-In

I decided to build a Trainwreck-inspired amplifier after reading a posting on The Gear Page by GeetarPicker (Glen Kuykendall) about how well a Ceriatone “Expression” had tested against a real Trainwreck Express amplifier.  Unfortunately I think the original ’shootout’ posting has been taken down, but there are lots of documented comparisons and other clone-related information on The AmpGarage as well. 

I bought an Expression in kit-form from Nik at Ceriatone. The complete kit of parts is shown to the right.  You can arrange to buy various levels of completeness from fully assembled amplifiers down to a ’bag of parts’ by talking directly to Nik via email. I opted for a standard ’package 2′ which consists of all the parts (except tubes), chassis, faceplate, transformers and pre-assembled/stuffed turret boards with wires coming off of them.

Ceriatone is constantly improving their products and my kit came with a new improved output transformer that better matched the original performance.  In the latest picture (shown on the left) the chassis now has an IEC power connector cutout instead of a dedicated power cord grometted in place. The faceplate logo has changed to a more politically correct chinese dragon instead of a copy of the Trainwreck logo.  Original Trainwrecks all had a wooden faceplate with a wood-burned picture custom to each amp, so I think the dragon is closer to the original idea. Trainwrecks are also built into wooden cabinets with a natural finish, not your typical tolexed variety.

Before we get started building this kit, however, you need some important reference material.  The layout provided at the Ceriatone site is mostly accurate and a good start. It is possible to get a very good results from the Ceriatone kit, but the Trainwreck Express is a very high gain amplifier that is barely under control and can be prone to excessive noise and even break into oscillation… layout and lead dress are key aspects of a successful build for this amp!  A layout drawing is a kind of visual schematic and the lead routing shown on those isn’t meant to be followed literally… you need experience or more detail…

With the Ceriatone kit it is possible to closely match the layout and lead dress of an original Express despite the changes in construction technique (e.g. turrets on 1/8″ thick FR4 instead of flea-clips on perforated 0.156″-spaced vero board)… You should study some original Express photos to prepare for the build.  Luckily, on AmpGarage a number of Trainwrecks are documented by photos, the most notable being Francesca: TrainWreck Pictures. 

Even better, DrHulsey on AmpGarage prepared a cool composite photograph of Francesca that he used as a reference for his successful cloning effort, documented in this thread: DrHulsey Build. I’ve downloaded his composite for your convenience and clicking on the picture to the right should get you the full resolution version.

Next time we’ll get started with the mechanical preparation of the Expression chassis…