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ELEX K2 (Hohner Stringvox) (r3): Tone Signal Route
K2-2
OS-5
(oscillator
dividers
& TOG)
(×9)
(single tone C –C)
On K2-2, the oscillator on the OS-5 board
produces the fundamental tone
(c.667,040Hz) which is divided by the
TOG chip to produce the top octave of
notes. These are passed directly to
some K2-1 boards but are also passed
through the divider chain to produce
successively lower octaves.
In each K2-1, when a note is triggered by
a keypress, a tone and its one-half
division are passed on separately as
Strings and Cello tones, and the two are
combined to produce the basic
Piano/Harpsichord/Bass tone (PHB).
The tones have their amplitude varied by
internal amplifiers controlled by the
velocity circuits and sustain pedal
(pianos), and decay controls (strings).
K2-14
Strings (bass)
Strings (treble)
Cello (bass)
K2-1
Cello (treble)
(×61)
PHB (bass)
PHB
(treble/all)
K2-110
(single tone C–C)
pedal board
Each set of tones is routed separately for
the bass (F1–F3) and treble (F 3–F6) key
groups. A single tone signal for C –C is
also sent through the pedal board if
used.*
The strings tones and PHB bass are sent
to the K2-110 board, where, according to
switch selection:
• The Cello and Strings tones are
grounded or passed to the K2-13 board,
where they are mixed, then sent to the
* Only twelve pitches are taken from the
K2-2 board and they are a single
waveform, IPN C 2–C3. I do not yet
know how this is turned into the pedals'
thirteen notes; does this pedal board
have its own divider circuit?
Strings (bass)
Strings (treble/all)
Cello (bass)
Cello (treble/all)
Piano (bass)
Harpsichord (bass)
K2-9
Piano (treble/all)
Harpsichord (treble/all)
Bass
K2-10
M175 assembly. In Full Keyboard
mode, the Cello and Strings bass tones
are combined with the treble tones in
the K2-110.
• Normally the PHB bass signal is
grounded or passed to the K2-9 board.
In Bass mode it is diverted to the K2-10
board, and the Bass voice replaces
both pianos and strings voices in the
bass range.
The PHB treble signal is sent direct from
the K2-1s to the K2-9. In Full Keyboard
mode PHB bass is combined with it at the
K2-2 output.
In the K2-9 board the signals are filtered
producing the Piano and Harpsichord
voices, then sent through the bass and
M175
K2-13
Cello+Strings
K2-6
Piano+Harpsichord (+Bass)
normal
Bass
Bass
treble Piano and Harpsichord attenuators
on the K2-13 board, and back to the
K2-110 board for final amplification, then
to the Piano/Harp output.
In the K2-10 board the signal is filtered
(together with any signal from the bass
pedals) producing the Bass voice. It is
then sent through its own attenuator on
K2-13, returned to K2-10 for final
amplification, then to the Bass output.
With no plug in the Bass socket, the
signal is returned to the K2-110 and
combined with the other pianos voices.
With no plug in the Piano/Harp socket,
electropict 2024
K2-20-2
K2-7
(×3)
volume
pedal
Cello+Strings
(with chorus)
normal
Piano/Harp
General
outputs
the pianos signal is combined with the
strings voices at the General output.
On the M175, the combined strings
signal is amplified in the K2-6 and
duplicated through the three K2-20-2
boards which each delay the signal by
varying amounts. Their combined
outputs are attenuated by the volume
pedal if used, and the final signal is
amplified in the K2-7 board and passed
to the General output.
(Earlier revisions used different boards in
place of the K2-110, M175, and K2-20-2
but with the same general routing.)
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