A Sound Investment

In December I was tempted by a couple of pre-owned locomotives I saw for sale online. One was a Proto 2000 GP20 painted for the Santa Fe that I thought about modifying to represent one of the 1990s-era TP&W GP20s that I grew up watching. The other locomotive was an undecorated Athearn SW1500 that I would have painted as TP&W #306. While the prices for each locomotive were reasonable, I opted against buying either of them because (1) I didn't want to add more locomotive projects to my queue and (2) neither of these locomotives was likely to get much run time on my layout, so my time and money could be better spent on something else. So, rather than add more locomotives to my fleet I decided to enhance one of my existing locomotives by adding sound. Quality over quantity.

On-board sound is a possibility for me now that I have converted my layout to DCC, but I've been a bit hesitant to take the plunge due to both the expense and the effort required to retrofit sound into older locomotives. At $100+ apiece, sound decoders are not only pricey but also cost more than I've paid for any of my locomotives. Most older HO locomotives weren't designed with sound in mind and the example installations I've seen tend to require milling of weights to make room for the speaker and/or have wires running everywhere under the shell. After my experience adding a non-sound decoder to my Proto 2000 GP30 I wasn't interested in an even more difficult sound decoder installation, but then I discovered the WOWDiesel kits from TCS. There are many versions of these kits that have been engineered to fit in specific locomotives.

The obvious candidate for my first sound locomotive was my favorite, C424 #801. WOWDiesel kit ATL-1 is designed for this Atlas locomotive and others that have similar mechanisms. No milling is required; you simply remove the rear weight and replace it with the speaker mount that's included in the kit. The kit includes a motherboard that's a drop-in replacement for the stock Atlas light board, so the wiring is limited to connecting the existing truck, motor, and headlight wires to the new motherboard along with the 2 speaker wires. The decoder plugs into the motherboard to complete the installation. The installation looked to be about as simple as a sound retrofit could be, so I decided to go for it. 

The starting point for this project. I'll reuse the DP2X non-sound decoder in a different locomotive.

The rear headlight is mounted on the rear weight, so removing this weight as part of the sound installation means I have to make a new rear headlight mount. Prior to disassembly, I took some measurements of the headlight's position. The top of the weight is 1" above the top of the main (black) frame and the tip of the LED is 1 15/32" away from the forward end of the weight.

I disconnected all of the wires from the original circuit board, removed the board, and removed the rear weight. 

Here are the contents of the WOWDiesel kit. From left to right, the decoder, the motherboard, and the speaker and its mounting hardware.

There are no printed installation instructions included with the kit. The TCS website has a comprehensive library of example step-by-step decoder installations with photos, and these are the de facto instructions for the kit. 

I snapped the motherboard over the tabs on the motor mounts, and then installed the 3D-printed speaker mount with the two screws provided. The two wires from the rear truck get routed up through the slots on the sides of the speaker mount and then under the leading edge of the speaker mount towards the motor.

Next I soldered the two purple wires to the tabs on the speaker. On my first attempt I soldered the wires going the other direction because I thought the tabs should go closer to the motor, but in this orientation the tabs interfere with the wires from the rear truck. I then reversed the purple wires so I could mount the speaker with the tabs to the rear of the locomotive. 

I installed the speaker in its mount (but didn't glue it in place yet) and then connected all of the wires to the solder pads on the motherboard. I approached the solder connections like lighting the candles on a birthday cake; start with the innermost locations and then work toward the outside (and try not to burn yourself). The wires to the rear LED seemed a bit short but the front LED wires were longer, so I swapped the two LEDs from their original placement. The red wires on the LEDs are the positive leads. Once I was done with the soldering, I installed the decoder onto the 21-pin plug on the motherboard.

The online instructions suggest using hot glue to attach the speaker to its mount but also caution not to get any glue on the speaker. I had zero confidence in my ability to neatly use hot glue for this task, so I opted to use a silicone adhesive instead.

Bruce Petrarca's article "How Do I Get the Sound Out?" in the August 2012 issue of Model Railroad Hobbyist does a great job of explaining how speakers should be mounted to optimize the sound quality. Basically, both sides of the speaker need to be isolated from each other so that the sound waves from the front of the speaker don't cross paths with the sound waves from the back of the speaker. The TCS speaker mount kind of does this by routing the sound from the back (magnet) side of the speaker down and out of the model around the rear truck, but there is nothing to stop the sound from the top of the speaker from going around the rear of the speaker mount and taking the same path out of the model. I decided to add styrene baffles to the front and rear of the speaker mount to force the sound from the top of the speaker to go straight up and keep it away from the bottom of the speaker. 

Here's the speaker mount with my baffles installed. The rear baffle doubles as the rear headlight mount, and I sized it based on the measurements I took before removing the rear weight. The bottom of the front baffle is slotted to clear the rear driveshaft and allow the rear headlight wires to pass through. I trimmed the tops of the baffles to match contours of the inside top of the shell at each location. I glued the rear LED to my new mount with Microscale Krystal Klear.

At this point, I tested the mechanism on the layout without the shell installed. Everything worked! The engine sounds seemed a bit quiet, but I figured they would be louder with the shell installed.

The baffles route the sound waves from the speaker straight up, but there were no openings on the top of the stock shell to let them out. To remedy this, I opened up 8 slots in the radiator grille. I drilled 8 #72 holes in each slot as shown, and then trimmed out the remaining plastic with my knife. 

 

Here's the bottom view of the completed slots. The clear plastic insert for the rear headlight and number boards prevented me from opening up any of the slots in the fifth row of the radiator grille.

I touched up the orange paint on the modified grille with a mix of 3 parts Vallejo Model Air 71.083 Orange and 1 part 71.130 Orange Rust. This mix was a bit lighter than the factory paint, but close enough for this application, especially after the next step.

To make the opened slots less obvious, I applied about 3 coats of Vallejo 76.518 Black Model Wash to give the radiator grille some depth. This product was easy to use and produced the desired effect, but I found that it took several hours to completely dry between coats.

Once the black wash was dry, I reinstalled the shell on the mechanism to test the complete installation. As expected, the engine sounds were much louder with the shell in place; however, I quickly identified three issues that I easily could have prevented before reassembling the locomotive: (1) the white styrene of the rear baffle was visible through the open slots; (2) when running in reverse, the light from the rear headlight was also visible through the open slots; and (3) when running with the sound muted, a soft thumping sound indicated that a wire was making contact with the drive train. None of these issues was critical, but they bothered me enough to take the shell back off and fix them now rather than later. The rear headlight issue was embarrassing. How did I not think of that?

I painted the rear baffle black and put a strip of black electrical tape over the exposed top of the rear LED. One of the black wires from the rear truck was touching the drive shaft, so I pulled the rear truck wires tighter and taped them to the front baffle. If I do another one of these installations in an Atlas locomotive, I might drill holes in the front edge of the speaker mount for the truck wires rather than routing them through the same space as the drive shaft.

With the installation complete, the next step was to program the appropriate engine and horn sounds. The Alco C424 was equipped with a 16-cylinder Alco 251B diesel engine. I haven't heard one of these running in real life, so I didn't know what it was supposed to sound like. The WOWDiesel decoder has two distinct options for the Alco 251. The one identified as "251 Turbo (Locomotive 1)" has loud, snorting exhaust, especially during the startup routine, while "251 Turbo (Locomotive 2)" is noticeably quieter. The names aren't very descriptive and I didn't know which option was best for the C424. I emailed TCS tech support and they told me that Locomotive 1 is a recording of an RS-23 (inline 6-cylinder 251C) and Locomotive 2 is a recording of an RSD-12 (V-12 251B). Neither is a C424, but I'm not bothered by that because I don't know enough about real locomotives to appreciate the nuances of various engines. I ended up selecting the Locomotive 2 option. 

I didn't know much about locomotive horns before this project. I knew that Leslie and Nathan were the two major horn manufacturers, but that was about it. The Five Chime Consultants Railroad Airhorn Guide (http://atsf.railfan.net/airhorns/index.html) was an excellent reference. After reading the airhorn guide and closely examining many prototype photos of TP&W 801, I concluded that the 801 was equipped with a Nathan P3 horn in the 1970s. The horn casting on the model is not a Nathan P3 and is not mounted in the correct location, but I decided to leave it as-is for now.  

The verdict? I'm very happy with how this project turned out. I think it sounds great, and the installation went pretty smoothly. I won't be equipping every locomotive I have with sound, but I probably will do so eventually for a few favorites. 

Boxcar Double or Nothing: Part 1

For my final modeling act of 2022, I stripped and repainted a pair of 40-foot boxcars. My primary motivation for starting this project was to practice masking a two-color paint scheme before I attempt to paint my GP30.

Microscale decal set 87-57 (on the left) has lettering for 5 different freight cars, one of which is TP&W 40-foot boxcar #6001. This car was painted red-orange with white stripes; the Microscale set includes decals for the lettering only so it requires a two-color paint job with masking for the stripes. Herald King decal set B-430 (on the right) is also for a red-orange TP&W 40-foot boxcar with white stripes. Back in 2018 I made a model of TP&W #60024 using this decal set and liked it so much that I tracked down a second decal set (these are long out of production) so I could do a second car. The Herald King set has decals for the white stripes so it doesn't need masking, but I figured I would go ahead and do this car now too.

Prototype photo of TP&W #6001. Date and photographer unknown.

As shown in the photo, TP&W #6001 had an 8-foot Superior (flat-panel) door and no running board. I decided to model it using an Accurail PS-1. The Accurail car is not an exact match for the prototype, but it has the correct door width, it's relatively easy to remove the running board, and (most importantly) I already had one on hand that I wanted to use. 

I've had this Accurail PS-1 for many years. It came factory-painted red with white boxcar data but no railroad lettering. It's been just sitting in its box for quite a while.

Accurail doesn't include Superior doors in their PS-1 kits but they do sell them separately. These doors are intended for one of Accurail's 50-foot boxcar kits and required a bit of trimming to fit my PS-1. 

The Herald King decal set is for a 40' car numbered in the 60000 series. For this car, I started with an Accurail 40' AAR boxcar lettered for the Great Northern. The Accurail car has a 6' Youngstown (corrugated) door. The prototype cars in the 60000 series had a variety of doors, and I decided to go with #60038 after finding a prototype photo that showed this car had the same door as the Accurail car.

 

I liked the 1960s-era red Great Northern paint job on this car, but I was willing to strip and repaint it because I'm a bigger fan of the 1970s-era TP&W red-orange and white paint scheme.

I used Super Clean Degreaser to strip the factory paint and lettering from both cars. The red paint on the PS-1 washed off very easily after soaking in the degreaser for about 24 hours. On the other hand, the red paint on the Great Northern car was much more stubborn and required a multi-day soak and a lot of scrubbing with a toothbrush to mostly remove. 

Here's the former Great Northern car after stripping the paint. I couldn't quite get all of the paint off, especially on the ends and the corners, but this should be good enough.

Here are the modified PS-1 body and doors prior to priming. I filled the running board holes on the roof with scraps of styrene, trimmed the plugs to match the surrounding roof, applied putty to gaps, and filed and sanded everything smooth. I had to remove about 1/32" from the bottom of each door so they would fit this car.

I primed both cars with Vallejo Grey Surface Primer (70.601). When I've used this primer in the past I haven't thinned it because the Vallejo FAQs say that thinning diminishes its polyurethane component and "the less dilution the better." However, I've had to spray it at a high pressure (~40 psi) due to its viscosity and it's been difficult to get a uniform coat. In one of his YouTube videos, Vallejo master painter Don Suratos recommends thinning the primer 1:1 with his "thinning sauce," which is a mixture of 2 parts thinner to 1 part flow improver. I tried his method for these two boxcars with excellent results. Many light coats of the thinned primer at 25 psi produced an excellent finish. I will always thin the primer from now on.

Here's the primed PS-1.

I let the primer dry for about 24 hours before spraying the sides of the PS-1 with Vallejo Model Air 71.001 White. For models like this one that will be decaled, I like to add Vallejo 70.470 Gloss Medium to the flat Model Air paints so they will dry shiny enough that I don't have to apply a separate clear gloss coat. A 2:1 ratio of paint to gloss medium has worked well for me. I also thinned this mixture 4:1 with the "thinning sauce," so the complete mix worked out to:

• 8 parts paint
• 4 parts gloss medium (70.470)
• 2 parts thinner (71.261)
• 1 part flow improver (71.262).

The primer is a very light grey, so it was difficult to tell where I had applied the white paint. For future models that will receive a coat of white, I might think about using a mix of grey and black primer for a darker undercoat. 

After the white had dried for 24 hours, I masked off the stripes on the PS-1 body and doors. I used strips of blue painter's tape for this. I used the prototype photo of #6001 and the Accurail doors to estimate actual thicknesses of 3/16" (about 16 scale inches) for the upper stripe and 5/64" (about 7 scale inches) for the lower stripe. 

I applied the masking tape to the doors first, then used the door as a guide to place the masking on the car body.

Here are the two cars prior to being painted orange.

I used Model Air 71.086 Light Red for the TP&W red-orange, mixed with gloss medium, thinner, and flow improver as described above. Next time around I think I'll try using the thinning sauce in a ratio of 3 parts gloss paint to 1 part sauce instead of 4:1 because the gloss medium is rather thick. I had some trouble with the paint drying in the tip of my airbrush, and I think additional thinning would probably help with that.

The first coat of Light Red always looks very yellow, but it gets much redder with additional coats. I applied the paint in many thin coats. I have to exercise a lot of patience to resist the temptation to apply thick coats for faster coverage.

Here are the painted PS-1 body and doors, ready for the masking to be removed.

The upper white stripes turned out great on the doors, but some orange bled under the tape on the lower stripes around the tack boards.

The stripes on the car body had a few small spots of orange but were otherwise pretty good.

My biggest fear for the masking was having the white paint pull off with the tape, but luckily this wasn't a problem except for one catastrophic spot on one of the door frames.

The bad spot where both the white paint and primer peeled off down to the red plastic. I'll touch this up, but thankfully this spot will be mostly covered by the door.

Overall I'd give myself a "B" for the painting and masking job on #6001. I think it's pretty good overall, but some touch-up is needed. There will be a Part 2 of this post once I've completed the touch-up painting and decaling of both cars.