It has been too quiet around here, so here is the start of a sound install in a brass Car & Locomotive Shop RS11. This is a “temporary” install as the locomotive has yet to be painted and re-detailed to eliminate its PRR heritage (a backwards horn.)
The C&LS engines that Henry Bultman imported some years ago have very smooth ball-bearing drives but very little starting torque, tending to jump like jack rabbits. This is due to a very low drive ratio and a custom-wound high voltage Pittman motor (not the typical 12 V 8-10A 8xxx.) The motor draws a locked-rotor stall current of only 1.2 Amps.
I gave up trying to get smooth operation with a Soundtraxx Tsunami. No manner of adjusting the back-EMF parameters would give smooth and powerful operation. Furthermore, the decoder kept corrupting its internal flash memory when a short circuit happened nearby, necessitating a factory reset and complete reprogramming.
This is an experiment with an HO-scale ESU LokSound V4 decoder. The V12 251 sound file is excellent.
The speaker used in this install is unconventional. Instead of a “hobby” speaker it is a Tang Band T1-1925S multimedia speaker. An oval passive radiator extends bass response a full octave, and it sounds great!
The module sits on a simple styrene frame that positions the passive radiator directly below the Alco’s radiator fan. The mounting tab on each end of the module has been cut off to save space.
Although the mount is shown resting on the frame, it will be installed in the car body and shimmed in place to prevent buzzing/rattling noises.
A small circuit board, to be mounted with double-stick tape after insulating the bottom side, provides screw terminals for the motor (upper right), left rail (top) and right rail (bottom.) A small 4 pin connector runs to the decoder mounted in the shell. A 1.5KE20 transient voltage suppression diode connects across the rails to protect the decoder from DCC bus ringing, particularly during short circuit episodes.
The circuit board facilitates dismantling the trucks from the chassis for painting, without having to unsolder anything.
I’ve already done this install in a C&LS RS36. It runs like a champ, smoothly creeps about 1 tie per 2 seconds, and burbles nicely with a surprising amount of bass. With quite a bit of momentum in the decoder, the V4 sound schedule comes into play. When switching the throttle can be slammed from stop to 1/2 or full throttle to drive the engine sound straight up to run 8, then the throttle can be quickly dropped once it gets to desired running speed. With a fast throttle reduction the sound will drop straight to idle but the motion continues, just as when a crew kicks cars while flat switching.