Larry Bergens adjustments to Loksound steam to give a better sound.
20 Dec 05.
Since installing my first LokSound decoder
I've been experimenting to improve the sound performance of my model steam
locomotives. I say "experimenting" because the decoder and LokProgrammer manuals are not too helpful when it comes to
understanding what the various control parameters do, or how to set values to
achieve desired effects.
One of my key objectives has been to enable
my steam locomotives to sound like they are really working up grade, and to
drift down grade almost silently. "Out of the box" my Mikado
sound files did not do that for me, so I was at first a little
disappointed. I did like it that there were at least some changes in the
chuffing as it sounded a
little louder as the engine accellerated, and got a little quieter while the engine was
coming to a stop. However, for my ear I wanted more difference in chuff
volume between accelleration, running, and drifting,
and I wanted more control over when the engine was "working", when it
was "running", and when it was "drifting".
I began by exploring the values set for the
random and user sound slots. I learned I could set the volume levels for each
sound independently. By default they were tied to Volume control 3 (auxilary). Further, by exploring the Sound Schedule I
learned that the chuff volumes were by default also tied to Volume control 3 (auxiliary).
To increase the overall chuff volume I first increased the Volume control 3 (auxilary) value found in Decoder "Sound Settings".
This sounded better, but now my random and user sounds were generally too
loud. So, I went into each of those sound slots, and reset the volumes
from being controlled by Volume Control 3 to specific volume settings (i.e.,
percentages). It took some experimenting with various sound volume
settings to achieve appropriate volumes to suit my ear, but it was very much
worth the effort. I was starting to get control over my sound volumes.
So, a little success in one area whetted my
appetite for more.
I ventured into the Sounds "Sound
Schedule" to experiment with some changes there. In each of the
sound slot groups D1, DA1, A1, DC1, and CX I explicitly set the volumes for
each chuff (there are four in each sound slot group). After some trial
and error, I arrived at the following volume percentages to suit my ear and
desire to have a greater distinction between accellerating,
running, and drifting chuff volumes. D1=40%, DA1=70%, A1=85%, DC1=30%,
and CX=20%.
Now I could better hear the distinctions
between accellerating, running, and drifting.
However, the changes between these modes were not occurring when I wanted them
too. When I opened the throttle to start the train I got the sounds of
the hard working locomotive I was looking for, but just as I was heading up the
grade on which the locomotive should continue working hard it would shift to
the quieter running (i.e., D1) mode. Similarly, when the train was
heading down grade it would continue chuffing in the running mode (i.e., D1)
until I was actually stopping the train. Only then would it go into drifting
(i.e., CX) mode. Not good.
Finding values in the Sound Schedule for
something called "Threshold", I began
experimenting with various values. The manuals provide no definitions or
guidance, so I was pretty much "on my own" to find out the effects of
changes here. After much experimenting I learned that
"Threshold" determines how much change in speed is required to shift
between running, accellerating, and drifting (i.e.,
coasting) modes. The big breakthrough came when I realized the effect of
positive vs. negative values. Basically, positive values trigger the
change in mode when the throttle is increased beyond the speed step
"Threshold", and negative values trigger the change in mode when the
throttle is decreased beyond the speed step "Threshold".
So, without walking you through all the
gyrations it took to arrive at these values, I ended up with the following
"Threshold" values. D1 to DA1=8, DA1 to A1=9, A1 to DA1=-1, DA1
to D1=-2, D1 to DC1=-3, DC1 to CX=-4, CX to DC1=1, and DC1 to D1=2.
Setting these values made a huge
improvement in my ability to control the chuffing of my locomotive with the
throttle. And, much to my delight, what I do with the model throttle
coincides closely with what a real 1:1 engineer also does to control how hard
his locomotive is working. Let me explain.
To move the locomotive "light" or
to switch short strings of cars where you don't want the engine to
"work" hard, you treat the throttle gently (much as if you were using
"direct" DC without momentum to gently start a train). These
gentle throttle changes avoid changing the mode to accelleration.
A little practice will help you learn how much you can gradually increase the
throttle to avoid going into accelleration mode, much
like a 1:1 engineer would do when not needing to accellerate
a heavy train.
To start a heavy train, simply open the
throttle more abruptly (i.e., with a speed step difference greater than the
"Threshold" setting required to move from running (i.e., D1) through
the transition (i.e., DA1) to accelleration (i.e.,
A1). The engine will work hard, and continue to work hard (staying in accelleration mode) until you slightly reduce the throttle.
The same is true when working up a grade. By opening the throttle an
amount sufficient to kick into accelleration mode,
the heavy chuffing will contine up the grade until
you reduce the throttle as the train is cresting the summit (much as a 1:1
engineer would do).
Similarly, you now have greater contol over running and drifting (i.e., coasting)
modes. While in running mode a reduction in throttle will drop the chuff
sound level to coasting mode. The sound level will stay in the quieter drifting
mode until you slightly open (i.e., increase) the throttle setting. So,
now you can simply reduce the throttle slightly when you come to a downgrade,
"drift" down the grade, and open the throttle slightly at the bottom
to return to running mode. Just like a 1:1 engineer would do.
The result of this experimentation has been
a dramatic improvement in my ability to control the sounds of my model steam
locomotives, and to obtain the effects I desire. I am much more satisfied
with the capabilities of my LokSound decoders.
I am especially pleased that achieving the effects I am after is enabled by
managing my application of throttle in a way similar to what a 1:1 engineer
would do.
I've shared the values (above) for various
parameters, as I have them currently set. I'm continuing to adjust these
values to find the settings that best enable me to control the chuffing with my
throttle to give the effects I desire. I'm also continuing to learn how
to manage my throttle to trigger and maintain the effect I want in each
operating situation. You may need
different values to fit your equipment (e.g., motors, gearboxes), DCC system
(e.g., Digitrax, NCE), and operating
objectives. I encourage you to experiment (as I have) and learn until you
achieve something close to the results you desire. Once achieved, these
values can be copied to other
locomotives in your fleet with similar
operating characteristics.
Regards,
Larry Bergen