Thanks to Fred Severson-QSI / Tony’s Trains Post for these details
QSI explains the long awaited improvements for diesel motor sound effects.
Q1a Early EMD Notching and Transitions
By Fred Severson, QSI
Our early EMD Quantum Sound Systems use a prototype model 567 non-turbo charged prime-mover as a sound source. The motor recording for our Quantum system has a noisy lifter, which is a common occurrence on these units particularly after many years of service. Early EMD sound is used in all F units, Geeps, and E units.
Early EMD locomotives had a very distinctive generator whine that could easily be heard whenever the motor was revved down. This along with the noisy lifter adds distinctive sounds that clearly distinguish the early EMD Quantum locomotives from our second-generation EMD Quantum locomotives.
In addition, early EMD locomotives had a unique transition effect that is noticeably different from second-generation EMD transitions. Transitions occur in the prototypes at different speeds depending on gear ratio. Our Quantum model will go through an automatic transition at 22 scale miles per hour.
Transitions have a similar purpose to manual transmission gear shifts in a car except there are no gears to shift. Diesel locomotives start out with their traction motors electrically connected in series, which allows full current available from the diesel-motor/generator to pass through the traction motors for maximum torque. As the motors gain speed, the current starts to drop off until even at notch 8, little additional current can be delivered and the locomotive reaches the maximum speed available in this configuration. Switching the motors from series to parallel connection allows additional current to be delivered to the motors, increasing traction and locomotive speed. This switching is called a transition.
As someone who has a deep appreciation for diesel locomotives…this is really “sweet sounding” news.
I remembe the lifter tap sound well well! During the late 1970s a good friend of mine and me got to see a good number of SCL’s 567 diesels in action. Most of them had racked up an obscene amount of miles between major overhauls. At idle, it was hard to miss that distinct lifter tap accompanying the baritone chant from the diesel. Up close you could literally watch the body panels on those SW8/9 switchers vibrating loudly against each other.
As I mentioned on another thread, as some locomotives aged their air let offs lasted longer during a burst. I’ve spoken to diesel mechanics before and vaguely remember that it had something to do with a certain component slowly wearing out. Some of the pop offs were about 3 to 5 seconds long. So far, the only system I’ve heard that offers the longer air pop off is Lok Sound on their Baldwin diesel swicher sound, which my friend downloaded and tailored to his SD45-2.
Looking forward to “hearing” this new chip in action[:D][tup]
Sorry, I tend to get sentimental over memorable sounds! [:P]
Though I’m hooked on Lok Sound and am looking forward to the new QSI chips…I can’t help but wonder if we’re really going to see the Soundtraxx Diesel Tsunami decoders soon.