7
EXTERNAL CLOCK SYNCING
Pamela can be driven by, and thus sync to, an external clock. This could be something simple
like a square wave LFO or something slightly more complex like a Din Sync or convert MIDI
clock signal from external hardware patched into the ‘Clk’ and run inputs. You can also control
the tempo directly with just a voltage level.
For syncing to work, Pam needs to know the external clock’s number of ticks (i.e clock pulses)
to a quarter note (i.e beat) - this is known as the Pulses Per Quarter Note (PPQN) value. A
mismatched PPQN value will cause Pam to report a very different BPM value to the external
clock - usually much lower. 24 is the
recommended
PPQN value to sync Pam with. Lower
PPQNs will not sync as accurately.
Pam also needs to know if it should start the clock automatically when an external clock signal
is detected or wait for an external gate signal via the ‘Run’ input to indicate the clock state
(high clock playing, low stopped). Its much better to use a Run signal as Pam can ’pre sync’
and doesn’t have to guess when a clock has stopped.
By default Pam is setup to follow a standard Din Sync like clock. A Din Sync clock is just a
clock signal with a 24 PPQN and a simple gate (into Run) which is high when the clock is play-
ing, low otherwise. It was used by various Roland drum machines and the like. Its really the
only standard ’analogue’ syncing protocol - thus the default for Pam and recommended way
to sync.
7.1
Syncing tips
•
Always use a 24 PPQN clock and a Run signal
Pam does not work like a simple analogue
style sequence where it simply advances a step on each incoming clock trigger, it has
to further divide the clock the down so a high resolution clock is critical for this. This is
what 24 PPQN provides. A ’RUN” signal allows for ’pre-syncing’ and avoids need to guess
when external clock has stopped.
• Modern MIDI clocking from a computer/hardware sequencer is generally fine assuming;
–
Your computer/device OS and DAW is up to date.
–
Your MIDI interface is from a reputable well supported brand.
–
You dedicate the physical MIDI line to only sending clock data. Sending note, pro-
gram change and other MIDI data on the same line can soon saturate the available
MIDI bandwidth and cause the clock to hiccup.
–
Your MIDI to ’analogue’ clock module or utility supports outputting a Din Sync like
clock. We strongly recommend our mmMidi (
https://busycircuits.com/alm023
module for this will which will provide a Din Sync like signal out of the box with no
configuration.
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