Been looking at the demo on youtube. Quite impressive . Couldn't quite
judge if the puffing is in sync with the piston positions. Don't know
anything about train classes, but the puffing timing suggested three
cylinders at slow speed, and as the speed increased, I thought it went out
of sync. Could be wrong. Anybody know if there's any attempt to sync and if
so are they somehow doing it in the DCC software without a local sensor?? My
project in hand aims to get the sound sync'd, but I'm using an optical
sensor linked to a driving wheel and the control is independent of the DCC.
Most (all?) UK RTR locos with sound use ESU LokSound chips. Those chips can
be run with or without a synchronising sensor (its a software setting in the
Most (all?) RTR models are built without a sensor, and instead use a
software approximation to the motor rotation speed (known from the motor
drive component of the chip). The approximation is usually good, but not
The cylinder beat will be in the sound file recording and the repeat loop,
again in the ESU chip's software. The quality is down to a mix of the sound
recording and the skill of the person setting up the ESU software.
The end user has some tweaking available in CV settings, but quite a bit of
a sound chip is locked to anyone lacking the original sound project source
out of phase with the pistons from the initial installation and would need
to be tweaked into phase during an initial run somehow.. And thereafter the
correct phase setting would need to be preserved when motive power is off to
resume correct operation when next switched on. I suppose they've catered
for this. Anyway thanks for the information. Appreciated.
You've missed a few bits: distance of listener from the locomotive, and the
human brain's ability to re-synch sound and pictures. So, unless you look
and assess things very carefully, the brain is remarkably good at making you
believe that things are synchronised. Thus doing all the synch things you
mention is probably unnecessary for many installations.
In very round numbers, if you are 100m from a real locomotive, the sound
takes about 0.33 seconds to reach you. At a fast walking pace (6m/s), the
driving wheels will have rotated 1/3rd of a turn before the sound reaches
you. The visual information (speed of light) travels the 100m in near
enough zero time. Yet your brain will happily put the two together and
suggest the sound and pictures are properly synchronised. (Your brain will
actually take quite a while before you conciously hear the sound and see the
image - 1 to 2 seconds - but the brain is very good at fooling you into
thinking its instant).
There are limits to what the brain will do; get the sound ahead of the image
and things go wrong, there is a limit on the delay synchronisation which is
accepted, and what happens does vary on the type of sound (lip synch for
speech in films/TV has different sensitivity to some other sounds).
- Nigel (Past professional experience researching human perception of
audio-synch issues in teleconferencing)