The sound of the diesel engine is controlled by the DC track voltage or by the DCC motor output, whichever is being used.
When the voltage is below 2 volts then the soundcard will produce the tickover of a static locomotive.
Once the voltage increases above 2 volts then the engine sound will accelerate in two different ways according to the type of diesel, as set at option switch 4:
This will match the starting voltage of modern, good quality locomotives. However, old or lower quality locomotives may not start moving until the track voltage reaches 4 or even 5 volts and the engine sound will accelerate before the locomotive starts moving. This problem can be overcome by inserting a resistor between the track and the soundcard.
If a battery is not fitted then no sound will be produced until the track voltage reaches about 6 volts.
