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Synchronization
ever, for various reasons, most professionals would work
using time-referenced code. For one thing, this is the only
way to sync additional machines up to the tape later.
A sequencer synchronized to tape has to calculate the bar
position from the time position, using its tempo track.
Bar-Referenced synchronization: First, a quick trip
down memory lane…
Pulse Clock and FSK (historical)
The original method of synchronizing analog sequencers,
or drum machines to each other was by transferring elec-
trical impulses (clock signals) at specific intervals. The
norm was 24 ppqn (pulses per quarter note), which is
equivalent to a resolution of 1/96 note. However, some
companies used 48 (Korg, Linn), 64 (PPG), 96 (Ober-
heim) or 384 ppqn (Fairlight). By way of comparison,
MAGIX midi studio generation 6 has a resolution of 960
ppqn).
By encoding these impulses as the “shift between two
pitches” (FSK code, frequency shift keying), it was possi-
ble to record this kind of code onto tape. It was mainly
used to synchronize drum machines to tape machines.
There were plenty of disadvantages to it, however
– FSK code laid down a fixed tempo.
– It was impossible to program intros/outros later.
Both Pulse Clock and FSK had two further disadvantages:
– If any impulses were lost through signal dropouts, the
synchronized devices would run constantly out of sync
from that point onwards.
– Because there was no position indicator, you always
had to start the song from the beginning (FSK 2 or
Smart FSK overcame this by encoding the song posi-
tion as well).
These disadvantages eventually killed off clock and FSK,
neither is now used professionally.
MIDI Clock / SPP: With the advent of the MIDI Standard,
an equivalent to clock impulses was incorporated into the
command protocol: MIDI Clock. MIDI Clock events are
transmitted by the master 24 times per quarter note. To
avoid having to start songs from the beginning every time,
a further MIDI command is also transferred: song position
pointer. This transmits 1/16 notes from the beginning of
the song. Because two data bytes are available for encod-
ing (14 bit), it is possible to distinguish a maximum of
16384 different 1/16 notes or 1024 bars. The slave recog-