Page 32 H0 Sound Decoder MX640
The following CV’s can be programmed both
“normal”
(i.e. CV #... = ...) and
“incremental”
(Ex-
ception: CV #280 for diesel engines).
“Incremental programming” is especially useful when the
proper value cannot be calculated in advance and must be determined by trial, which is often the
case with many sound parameters.
The “Lead CV” in each case is the first of 3 consequential CV’s that are edited and shown on the
same screen of a ZIMO MX31 during the “incremental programming” procedure.
CV
Designation
Value
range
INC
steps
De-
fault
Description
LEAD
- CV
#266
Total volume
0 - 255
5
65
The value “65” results (mathematically) in the
highest possible distortion-free play back volume;
but values of up to 100 can be perfectly suitable
because distortions in this volume range are
hardly audible. Plus, the usefulness of a sound
also depends on the quality of the sound sample
used.
#267
Chuff sound fre-
quency with „virtual
cam sensor“
For STEAM engines
0 - 255
1
70
CV #267 active only if
CV #268 = 0:
Chuff beats follow the “virtual cam sensor”; an ac-
tual cam sensor is not needed in this case.
The default setting “70” results in about 4, 6 or 8
chuffs per wheel revolution, depending on the
chuff set selected; because it also depends in
large part on the motor and gearbox used, an in-
dividual adjustment is necessary in most cases in
order to achieve the desired chuff frequency. This
is the reason for CV #267:
The lower the value the higher the chuff frequency
and vice versa.
#268
Switching to real
cam sensor
and
trigger count for chuff
rate
For STEAM engines
0 - 255
1
0
= 0: “Virtual“cam sensor is active (to be adjusted
with CV #267, see above).
= 1: real cam sensor is active (connected to switch
input 2 of the MX640, see chapter 8); each
negative spike results in a chuff beat.
= 2, 3, 4 … real cam sensor, several triggers in
sequence (2, 3, 4 …) result in a chuff beat.
LEAD
- CV
#269
Lead-chuff
accentuated
For STEAM engines
0 - 255
10
0
A typical sound signature of a passing steam en-
gine is that one chuff out of a group of 4 or 6
chuffs is louder in volume than the rest; this effect
is already part of the chuff set but can be further
amplified with the help of CV #269.
# 270
PROJEKT
not functional yet:
Longer chuff length
at very low speeds
For STEAM engines
0 - 255
10 ?
PROJECT (not yet implemented):
The chuff sounds of a real engine are extended
when driving at very low speeds due to the me-
chanical valve control. This effect can be more or
less accentuated with CV #270.
#271
Overlapping effect at
high speed
0 – 255
(useful
up to
1 16
The individual steam chuffs should overlap each
other at high speed like on a real engine. Because
the frequency of the chuffs increase but won’t
CV
Designation
Value
range
INC
steps
De-
fault
Description
For STEAM engines about
30)
shorten to the same extend they will eventually
blend in to a weakly modulated swoosh.
This is not always desired in model railroading
because it doesn’t sound that attractive, hence CV
#272 with which an adjustment is possible
whether the chuffs should be accentuated at high
speed or rather fade away.
LEAD
- CV
#272
Blow-off duration
For STEAM engines
0 - 255
=
0 - 25 sec
10
50
=
5 sec
Opening the cylinder valves on a prototype steam
engine for the purpose of water drainage is en-
tirely up to the engineer. An automated draining at
start-up is more suitable in model railroading; CV
#272 defines how long after start-up the blow-off
sound should play.
Value in CV #272 = time in tenths of a second!
Note: If the blow-off sound is also allocated to a
function key (on F4 as delivered, see CV #312),
the automated blow-off sound can be shortened
or extended with the relevant function key. Auto-
mated blow-off and function blow-off are inevitably
the same (per selection/allocation).
= 0
: no blow-off sound played back
#273
Delayed start after
blow-off
For STEAM engines
0 - 255
=
0 - 25 sec
1 0
Opening the cylinder valves and with it the related
blow-off sound on a real steam engine starts most
often before the engine even starts to move.
This can be imitated with CV #273 by automati-
cally delaying the start.
This effect is cancelled when a shunting function
with momentum deactivation is being activated
(see allocation of F3 or F4 in CV #124!)
= 0: no delay
= 1: Special setting for blow-off via speed
regulator; no delay but the lowest speed step
means “no driving but blow-off instead” (only
with 128 speed steps).
= 2: Start-up delay in tenths of a second,
Recommendation: no value > 20 (> 2 sec
#274
Blow-off schedule
For STEAM engines
0 - 255
=
0 - 25 sec
10 30
During shunting operations that often requires
many short trips with associated idle times, open-
ing and closing the cylinder valves every time is
