MR Magic WebsiteThe Whitby Loco



The Whitby sound system is indeed a 4-way speaker system! Although it is technically a monaural system, any "voice" in the Whitby soundtracks can be mixed and sent through reverbs, delays and flanger/phasing processors for routing to separate amp/speaker systems all over the layout! Shown here are the JBL 31/2" midrange (face down in the saddle tank), and the two-way Motorola piezo tweeter system components (face down in the cab, and face up in the stack), there is also an external JBL 8" tuned port sub-woofer fed via an external electronic crossover and power amplifier (not shown). A 9v battery rides in the steam dome, and the onboard 9v receiver and amplifier are mounted inside of the saddle tank/speaker enclosure. A live mix of the mid range and high frequency cartoon "steam operation" sounds (along with any ambient FX signal processing such as reverb when the loco is in a tunnel) is broadcast to the loco using the rails as the FM broadcast antenna. A wire receiver antenna is hidden from view in the base of the saddle tank and running boards.

Enclosure Design
Speaker enclosure design for the Whitby existed even before the exterior design was complete. In fact, the speakers were chosen and the enclosure built first, the rest of the loco was built around these elements and the LGB motor block. The smoke box, saddle tank, steam dome, stack and backhead are all part of the overall enclosure housing. These components were fashioned out of thick black PVC pipe chosen in part for its acoustic dampening, and from solid 3/8" thick walnut, epoxied and clamped together. The saddle tank and backhead were created from "annealed PVC" (that's PVC pipe cut, heated, and then bent into the appropriate shapes).


Speaker system components were carefully chosen for efficiency and their ability to speak precisely and efficiently. At the heart of the Whitby's onboard audio system is a single JBL Inc. T-105, 31/2" automotive drop-in replacement speaker mounted face down in the botom of the saddle tank. I suspect this speaker is no longer available, as at $50.00 a pair it's not likely too many were ever sold. Still, like all JBL's, it is an extraordinary speaker for its size, and virtually indestructible. I still have the second one of the pair if it should ever become necessary, but in hindsight I wish I had bought a case of them.

The complete loco audio system is a four-way system... of sorts. It is an unconventional four-way system design for any of several reasons. On board and traveling with the loco itself are the T-105 and two Motorola Piezo (pronounced pee-A'-zo) Ceramic tweeters, a cut-down KSN 1034A face down in the cab roof, and a KSN 1020A face up in the diamond stack. Piezo ceramics, unlike conventional inductive transducers, have no magnet or voice coil. They are simply a thin ceramic wafer which expands and contracts when there is an audio voltage present. Except for an electronic crossover which processes the signal to the sub-woofer, the three way loco speaker system operates on a full range amplified signal without any active or passive crossover components at all. This is due to the unique properties of the piezo ceramic transducers which naturally roll-in at the higher frequencies all by themselves. They are oblivious to low frequencies and therefore need no protection from them. The T-105, like any cone, naturally rolls off at the high end.

A JBL M-80, 8" tuned port speaker in a separate enclosure working below 80 Hz serves as a sub-woofer for the loco, and also the entire railroad. The Whitby sound system is quite capable, but to say that it sounds natural all by itself would be misleading. More about this later.

There are a number of nifty FX devices available that can easily and automatically recreate the various delay/reverb characteristics encountered on any railroad. These are usually digital devices pre-loaded with algorithms that can simulate anything from long distant discreet delays to the slap-back/reverb of a tunnel interior, or most anything in between. For the Whitby loco I chose a musical instrument analog tape loop delay with a built-in spring reverb and a lot of noise (both electronics hiss, and Ampex 451 tape hiss!). Any sound that is sent directly to the loco can be processed with any combination of echo, delay and reverb times, and then mixed in along with the direct sound sent to the loco, to simulate any ambience the loco might encounter. A separate "free-running" digital delay only (no original sound, just the delayed echoes) is sent to speakers hidden in various mountain peaks and faces. When the Whitby speaks, everybody listens. A similar system of distance enhancement is employed on the station announcements.
Audio System

The Whitby Audio System Simplified Block Diagram

FM Broadcast
I'm not certain if they still make the Transponder Animator, but Starr-Tec's sound system is the only commercially available system that allows sound to be completely created from an external fixed position on the layout. This clever device broadcasts the signal up the rails to make an FM "jump" up to an on board 9v battery powered receiver/amplifier/speaker system. The idea is to eliminate the noise that is created by "through-the-rails" systems (systems where audio is impressed along with the DC power through the rails and loco's wheel pick-ups), where dirt on even fairly clean track made loud scratchy noises. The Transponder Animator eliminates the mechanical connection noise entirely, but does require an external sound/program source such as cassette players. Up to four monaural inputs can be mixed and sent to the loco FM broadcast link, and/or to either of two additional amplified outputs. The need to provide your own program source (locomotive sounds) was most likely the reason that this system did not gain more popularity, but is exactly the reason I love it. I wanted to create each and every voice with which the Whitby speaks, and moreover, optimize those voices to literally leap out of the Whitby's three on board speakers! Additionally, I wanted to be able to process those voices to sound correct when the loco is in a tunnel, or squealing around a tight curve, or crawling along a "solid" rock face. And, I wanted to be able to do this "on-the-fly".

Voice Creation
I have collected or sampled a substantial number of steam and "steam-like" sounds over the years. Some of these include waterfalls (for watery steam hissing), an industrial water heater (for stunning boiler/burner bottom end rumble), and several steam operated pieces of machinery (for steam valve opening/closing and mechanical sounds). These are then sampled into a digital audio workstation (DAWS) for editing and for various forms of signal processing. The Whitby loco is connected to the computer workstation outputs through an amplifier, to the loco speakers directly, bypassing the broadcast loop. This allows us to monitor the sounds through the actual speakers that they will be played on every time it is performed, while we are working on them! This is called a L.I.V.E(TM) Mix-down (Listening Interpretation Via Event/Environment), a technique developed by Fantasonics(TM) Engineering for theme park attractions. Each voice is tweaked in the DAWS, most often with 10 band parametric equalization. Anomalies in the speaker system can be compensated for quite accurately in this manner. The whole thing is tuned by ear, in that we simply keep tweaking until each voice sounds real (and/or funny).

Once an individual voice is optimized, it is saved as a sound file for eventual sampling into keyboard digital musical instruments, or for compositions directly in the DAWS system. Complete operating sessions can be "performed" on the keyboard for MIDI (Musical Instrument Digital Interface) playback, or composed in the computer for mixdown to a mastering medium such as CD. Of course all this is much more involved than can be described here, but this basic production sequence is always the same.

External control, CD/sampler voice
Here at the house, I often play MIDI/keyboard or Sound Designer II files directly into the layout broadcast system. But for portability I do not want to drag the Mac G3, MIDI interface, and keyboards around. For this reason I make CDs which contain the various pieces of an "operating session". The various pieces of a complete session are burned onto each of three CDs in a way that allows cross-cueing (cueing the next sound on one CD player while a current sound plays on another). The third CD is allocated to "solo voices", such as whistles, bells, blow downs, wheel and brake squeals, etc.