Mindheim Sound

I revel in both the writing and works of noted model railroad custom builder Lance Mindheim. As a result, I’ve adopted most of his concepts and practices in the art of model railroading for The Hills Line, and consider him a mentor, colleague, and friend.

Recently he shared a video of his Downtown Spur layout filmed by Miami-area railfan and videographer Tolga Elbora. At the 1:46 mark into the video, Lance mentions he’s going to switch on the under-table sound on his layout. The room, and therefore the video, is instantly filled with the low-growl of an EMD 645 prime mover.

My jaw dropped at that moment.

Original Image © Lance Mindheim. All Rights Reserved

Now Lance had previously written about his development with under-layout sound connected to a pair of wireless headphones. At the time I either missed, ignored, or didn’t realize its full potential. I am now atoning for that mistake. Fortunately Lance is as supportive with fellow modelers as he is talented. After reaching out to him, he updated me on his setup so that I could attempt to replicate it for my own use.

I started with a proof of concept and mockup using a Tsunami 1 decoder I had left over from my fleet upgrade a few years back. The first step was to solder a 100 Ohm resistor across the motor leads so that the decoder would detect the load and allow me to program it.

Then using an older stereo set I temporarily connected it to the speaker outputs of the Tsunami, and ran a power feed from the track. Once the layout was energized a similarly low-growl filled my basement.

With the proof of concept confirmed, it was time to maximize the quality and amplitude of the sound. Lance mentioned that he uses a Radio Shack Audio Output Transformer, part #273-1380. However that particular item has been discontinued for quite a while. A scouring of eBay and other online sites allowed me to track one down.

I assembled the components on a scrap piece of wood using spacers and double-sided foam tape. Terminal blocks allow me to make and break wiring connections as needed. The entire arrangement was then mounted under the layout and connected to the track bus.

For the output, I stepped up my game. I was able to acquire a DEWALT Jobsite Bluetooth Speaker to place on the shelves underneat the layout. The audio feed was connected to the speaker’s auxilary input. I’m able to adjust the overall audio directly, but still programmed the decoder’s sound levels to suit the space.

To function, each of my locomotives is in a permanent consist with the under-table sound decoder. Since I only run single units on The Hills Line, there’s no need to adjust the settings as I swap from unit to unit.

Overall this setup is a great addition to the soundscape of the railroad. However I do want to eventually replace the Tsunami with an ESU Loksound so that it matches the rest of my locomotive fleet. And since the speaker is portable and bluetooth-enabled, I’m looking forward to seeing what other aspects I can add in the future.

5 thoughts on “Mindheim Sound

  1. So I’m guessing the BT speaker’s aux in is a single stereo cable? If so do you just crack that open and I assume it has two separate wires in it for left/right which is what you have shown as the black/red going somewhere out of view in your photo above? Thanks, I just got my transformer off ebay today.


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