QSI QS-2plus!, Manual

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Section 6 RESET Feature Guide 70
#27: Steam Chuff Threshold and Chuff Rate
or Diesel Motor Threshold
Chuff Threshold is the throttle setting where your steam engine begins to chuff.
Chuff Rate is the number of chuffs per revolution of the wheels. Motor
Threshold is the throttle setting where your diesel engine begins to rev up.
Each engine's electric motor and gearing is different, and each type of
transformer applies power to the engine differently. QS-2+ is designed to give
you excellent sound effects under a wide range of conditions. However, if you
do not like QSI's settings you can adjust the threshold and rate to suit your
individual locomotive.
The QSI chuff and motor settings change depending on the transformer QS-2+
identifies during RESET. QS-2+ will remember settings for individual
transformers, either in Auto Select or under individual transformer types. But
to be sure the new setting is stored under your particular transformer in QS-2+
memory, it's a good idea to wait until the transformer is Auto Selected (the first
time you bring the throttle to a low setting after the power has been off, you will
hear "pssht, pssht" as QS-2+ selects the transformer), or lock in the transformer
type you are using with RESET Position #19 before continuing with this
RESET Feature.
MORE: QS-2+ Eliminates Cams
Normally model railroad locomotives use a mechanical cam to detect how fast the wheel is rotating, and
for steam engines, this information is translated into a chuff sound that synchronizes with the speed of
the locomotive. Adding a cam to an engine requires modifying the engine, an expensive and often
difficult process. And cams lock your engines into a specific number of chuffs per wheel revolution,
regardless of speed. QS-2+ is designed to electrically detect engine speed directly from the electric
motor. This method of measuring speed from the motor allows the chuffs per wheel revolution to vary
depending on speed. At slow speeds the number of chuffs per wheel revolution is set at a realistic four
chuffs. But the chuffs gradually decrease to about two per wheel revolution as the engine runs faster.
This is ideal for three-rail engines, whose top speed is unrealistically high. If the chuff rate did not
decrease, the chuffs would blur into a single sound.
1. Setting Steam Chuff Threshold and Chuff Rate
If you apply power and notice your engine starting out without chuffing, or
chuffing before it even moves, you can adjust the chuff
threshold to more
accurately fit your engine. Also, if your engine is chuffing too slow at high
speeds, or chuffing too fast at low speeds, you can adjust the chuff
rate .
Note: While setting the threshold and rate, the chuff or motor sound volume
will be at maximum. If you lowered the volume using RESET Position #6, the
volume will return to this lowered setting as soon as you leave this RESET
Feature.