Weston Precision Audio H1 Analog Harmonizer User manual

© 2023 Weston Precision Audio
1
H1
Analog Harmonizer
Eurorack Module
User Manual
Weston Precision Audio
Designed In Portland, Oregon
Revision 03 - July 26, 2023

TABLE OF CONTENTS
Quick Start Diagram…………………..…3
Description & Specs………………………4
Controls……………………………………..5
Inputs & Outputs…………………………..6
Using H1
!Description Of Modes……………8
!Main Modes (Main/Chord)…….9
!!Diatonic Chord Mode….10
!Track/Free Channel Setting……11
!Quantizing……………………..…12
!Oscillator Sync……………..……12
!Oscillator Detune………………..13
!Mix Pad……………………………14
!Octave Control…………………..14
!Osc In Tuner Mode……..……….14
Appendix
!Updating Firmware…………….15
© 2023 Weston Precision Audio
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© 2023 Weston Precision Audio
3
Plug output of VCO
with clean periodic
waveform here to
have H1 track its
frequency
First, for quick start, hold the option button and make sure
this button is unlit. If not, press it until it is unlit. This will put
us in Main/Normal mode for quick start purposes.
This is the option button.
Hold it to see applicable
options illuminated and
access the secondary
functions of those buttons
With option held, yellow
means active channel is in
free mode (acts like
regular VCO), white
means track mode
(channel follows frequency
of “Osc In”)
Any of the 12
“keys” buttons
selects base interval
of active channel
relative to “Osc In”
(Track Mode) or to
middle C (Free
Mode) (C, C#, D,
etc..)
Mix output contains a mix
of “Osc In” (left knob) and
mix of channel A+B
triangle, saw, and square
(right 3 knobs)
Option + A/B flips
between viewing base
interval of active channel
and control of active
steps for quantizer
CV output gives either
voltage proportional to
“Osc In” frequency OR
quantized voltage of CV
in (option + CV Out) to
toggle
All OUTPUTS have a box
drawn around them. All
INPUTS do not
These LEDs show active
channel being edited
H1 Quick Start
(Save the manual reading for a rainy day, right!?)
This button (A/B /
Display) toggles
active channel

DESCRIPTION
H1 is a Eurorack module designed to
make it easy to add harmonic layers or
basic polyphony to your modular
patches. It is primarily designed to be
used by patching the output of a VCO to
the “osc in” input and letting the H1
derive 2 notes that are related to the
pitch of that oscillator (ie a 3rd and 5th
to form a major triad for example).
However, H1 can also be used as a dual
quantizer, a frequency-to-voltage
converter, or simply as 2 analog VCOs.
The choice is yours.
At its heart are two identical channels of
digitally-controlled, pitch-tracking
analog oscillators and 2 quantizers. The
oscillators make use of precision
multiplying DACs (digital to analog
converters) and stable reference
circuitry so they are extremely stable in
pitch and tracking, but at the same time
their signal-generating parts are
completely analog so they impart the
full richness of an analog oscillator. To
be clear, H1 is NOT a digital or
wavetable oscillator.
An output mixer section completes the
package and minimizes patch cord
clutter by giving a mix of the pitch-
tracked input signal and the 3
waveforms of the 2 oscillator channels.
Each channel also can be modulated
with true analog through-zero FM.
Important or helpful bits will be in red.
SPECS
Module Size: 18HP
Depth: 25mm (To back PCB), 33mm (To
end of power connector)
Audio Outputs:
<=1kOhm Output Impedance
Inputs (All inputs >=100kOhm
Impedance): CV, Trigger, Lin FM, Osc In.
Power input:
+12V & -12V via standard 10 pin
Eurorack connector. Protected against
reverse polarity internally and with
shrouded connector.
Power consumption (+12V / -12V):
Typ: 185mA / 75mA
Max: 200mA / 85mA
ADC Resolution (CV ins):
12-bit
DAC Resolution:
Main osc. channels: 16-bit
CV outputs: 14-bit
USB firmware update port:
Micro Type-B
MAXIMUM LIMITS
Supply Voltage: +13.5V / -13.5V
All inputs: Up to power supply levels.
© 2023 Weston Precision Audio
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MAIN CONTROLS
Most functions of H1 are controlled
through the row of LED-backlit buttons
on the top of the module:
You may notice the leftmost group of 12
buttons is arranged as an octave of a
standard piano keyboard. The next
column of buttons is an octave control.
Finally, there is the display/AB button
and the Option or “circle” button.
Text written above or below a button
refers to the button’s function while
HOLDING the Option button. For
example, the A/B button on its own
toggles between selecting channel A or
B. If Option/circle is held and this same
button is hit, the “display” function is
invoked. More in this later.
OTHER CONTROLS
Detune:
If detune is enabled for the
selected channel, this pot
provides a fine detune for the
selected channel with a
range of +/- one semitone. If
detune for channel A is
adjusted, and then channel B is selected
and the knob is turned, the knob will not
effect channel A’s detune when
returning to channel A until the knob is
turned back to the point at which it was
set while the channel was active. If
detune is disabled for the channel, the
detune knob will have no effect.
FM input attenuator:
Each channel has an input for analog
through-zero frequency modulation
(TZFM). The knob next to each jack
controls the amount of FM signal
applied. That is to say it is simply an
attenuator for the input signal.
Mixer:
H1 has a mix output which contains a
mix of whatever signal is input to “Osc
In” and the 3 primary waveforms from
each oscillator. The 4 potentiometers,
from left to right, control the amount of
“Osc In”, Triangle A + Triangle B, Saw
A + Saw B, and Square A + Square B.
The mixer section has a gain of either 1
(0db), or -9dB if the “Mix Pad” feature
is enabled. The Mix Pad option gives
more effective headroom to crank the
mixer controls up more without clipping.
© 2023 Weston Precision Audio
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INPUTS
As noted in the Quick Start, all outputs have a border
drawn around them on the panel, and inputs do not.
This standard will be adhered to on future Weston
modules.
Oscillator In (Osc In)
The Osc In input
accepts a periodic
waveform with
amplitude ranging from
around 1Vpp to 20Vpp
and determine’s that
waveform’s frequency.
The signal input must be of a single
primary frequency (e.g. from a VCO or
self-oscillating filter) in order to get good
frequency-tracking results. If the signal is
highly wave-folded or filled with other
strong frequency content, glitching and
jumping can occur. This may be enjoyed
by some users though, so by all means
experiment and abuse this input if you
wish!
In track modes, the closest note of the detected
input signal will be displayed as a pulsating
white/yellow light on the keypad
In short, the waveform to be accurately
frequency-tracked must have consistent
zero-crossings. See table below for
some examples:
Primary CV and Trigger
Each channel has a primary CV input
which controls the relative pitch of that
channel. It can be quantized (more on
that later) and has an input range of -3V
to 7V.
Each channel’s quantizer also has a
trigger input. When trigger in is
enabled, the quantizer will only output
the next quantize step if a rising edge of
the trigger input is seen. This trigger
voltage can be anywhere from around
1V to 12V.
Linear FM
Each channel has a Lin FM input which
allows that channel’s oscillator to be
through-zero frequency modulated by
the signal input to this jack.
Auxiliary CV (CV2)
There is also an auxiliary CV input
(labeled CV2) which, when enabled,
can either transpose the base note of
one or both channels, or transpose the 2
notes of a chord pair together when in
Chord Mode (more on this later).
© 2023 Weston Precision Audio
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OUTPUTS
CV Out & Trigger Out
Each channel has a CV output which
can be set to operate in 2 different
ways. Holding the Option key and
pressing “CV Out” will toggle between
the 2 and change the status color of that
button as follows:
When illuminated white, the active
channel’s CV output will present a
voltage which is proportional to the
frequency of the “Osc In” signal, in a 1
Volt/Octave scale. Thus, in this mode,
H1 is essentially functioning as a
FREQUENCY TO VOLTAGE converter.
When illuminated yellow, the
active channel’s CV output will
present a quantized version of the
voltage input to the corresponding CV
input. It’s behavior depends on the
quantize mode described later in the
“UsingThe H1” section.
Next to each CV Out jack is a Trigger
Out jack. If the H1 is being used as a
quantizer and the Trig Out option is
enabled, a trigger pulse will appear
here each time the active quantize step
changes. The signal amplitude is 5V and
has a pulse width of 1millisecond.
Individual Wave Outs
Each channel has outputs for the 3
primary waveforms from that channel’s
oscillator: Triangle, Sawtooth, and
Square. These can be used for more
complex patching and mixes outside the
H1.
Mix Out
For simpler patches and for keeping
patch cord clutter minimized, the mix
output can be used. As described in the
controls section, this mix contains a mix
of “Osc In” and the combined primary
waves from channel A and B (Triangle A
+ Triangle B, Saw A + Saw B, and
Square A + Square B) which are
controlled by the knobs immediately
above the mix out. The mixer section has
a gain of either 1 (0db), or -9dB if the
“Mix Pad” feature is enabled. The Mix
Pad option gives more effective
headroom to crank the mixer controls up
more without clipping.
© 2023 Weston Precision Audio
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USING H1 - DESCRIPTION OF
MODES
H1 has 2 distinct modes of operation:
Normal, and Chord. Chord mode has 2
versions: Stored Chord and Diatonic
Chord.
Main Mode:
Each channel’s oscillator note interval is
simply selected with the keypad. This
interval can be selected with the
channel’s CV in and used like a
quantizer with the note enable/disable
page.
Stored Chord Mode:
Each channel’s oscillator note interval is
determined by a stored chord table.
There are 12 slots to store chords and
these can be selected with channel B’s
CV in.
Diatonic Chord Mode:
Each channel’s oscillator note interval is
determined by the appropriate diatonic
triad for whatever the pitch basis is
(either Osc In in track mode or CV A in
in free mode). The key of the diatonic
scale can be selected with channel B’s
CV in. The key can be minor or major by
pressing Option + Octave up or down.
A summary of these modes is provided
in the table above.
© 2023 Weston Precision Audio
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Summary of H1 modes and input functions
Track
Free
Track
Free
Track
Free
Track
Free
Osc In
CV In A
CV In B
CV In 2 (Aux CV)
Main/Normal Mode
Pitch basis
for
channel
A/B or
both.
Nothing
Ch. A Note Interval
Ch. B Note Interval
Transposes Ch. A/B or
both note intervals
Chord
Modes
Stored Chord
Pitch basis
for both
ch.
Nothing
Nothing
Pitch basis
for both
ch.
Selects chord 1-12
Transposes active chord
(If CV2 Option is on)
Diatonic Chord
Pitch basis
for both
ch.
Nothing
Nothing
Pitch basis
for both
ch.
Selects key of diatonic
scale
Selects major or minor
diatonic
(If CV2 Option is on)

USING H1 - OPTION KEY AND
MAIN MODES (NORMAL/CHORD)
At any point while using H1, you can
hold the Option button (the one with the
circle around it) and see applicable
options and modes. Let us start with the
primary modes of operation. Holding
Option look at the E-flat key (with
“chord” above it):
In Normal Mode:
In Stored Chord Mode:
Both modes are fairly similar and differ
in this way:
NORMAL MODE: Each channel’s base
interval is selected with one of the 12
“key” buttons on the first display page
(“DISPLAY” is unlit) and this note can be
modulated by that channel’s CV input
and optionally quantized. If it is
quantized, the quantize steps can be
selected on the second display page
(“DISPLAY is lit yellow). Option + A/B
toggles display page
CHORD MODE: Both channel’s base
intervals are displayed and controlled
on the first display page and the active
chord is displayed on the second display
page. There are 12 “slots” to store these
“chords” or 2 note combinations in,
corresponding to the 12 “key” buttons.
Chanel B’s CV input is used to select a
chord slot using CV and CV2 can be
used to transpose the active chord with
CV.
Examples of page 1 view in each
primary mode:
In Normal Mode:
Active channel’s base interval is lit in yellow. In this case it is
set to a 3rd or “E”
In Stored Chord Mode:
Channel A’s base interval is lit in yellow and Channel B’s
base interval is lit in white. Active channel is still selected
with the A/B button just as in Normal Mode.
© 2023 Weston Precision Audio
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Examples of page 2 view in each
primary mode:
In Normal Mode:
The active Chanel’s active quantize step is lit in yellow and
the enabled quantize steps are lit in white. All steps are
enabled in this example.
In Stored Chord Mode:
The base chord slot is lit in yellow (in this case slot 6) and the
CV-shifted active chord slot is lit in white (in this case slot 9
or 6 + 3).
When in stored chord mode and in
page 2 view as shown above, the base
chord slot is selected by pressing a key
1-12. Holding that key for 2 seconds
saves that chord to non-volatile memory.
The keypad will blink white a few times
to signify it has been saved.
DIATONIC CHORD MODE
When holding Option, the
CHORD button (E flat) will light up
YELLOW instead of yellow if in
Diatonic Chord Mode. This mode takes
the root input (From either Osc In when
in track mode or CV A In when in free
mode) and generates the diatonic triad
for that note. This is very helpful
because all diatonic chords always have
the notes of that particular scale in them
and thus they never sound musically
bad.
On the second page of Diatonic chord
mode (Option + Display to toggle
pages), the key of the scale is shown. So
for example, if “C” is selected on the
keypad, and a “C” is provided to Osc
In, then H1 will generate an E and a G,
because a C major is the first diatonic
chord of the C major scale. If a “D” is
provided to Osc in with the same scale
setting, H1 will generate a D minor (F
and A), and so forth.
The key of the diatonic scale can be
selected through the keypad on page 2
as described above, and can
additionally be selected via CV In B.
Finally, the diatonic chords generated
can be of a major or minor scale. Major
is selected by pressing Option + Octave
Up, and Minor is selected by pressing
Options + Octave Down. This can also
be selected via CV via CV 2 In (Aux CV
In). Any “white key” CV will cause the
scale to be major, and any “black key”
CV will cause the scale to be minor.
© 2023 Weston Precision Audio
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USING H1 - TRACK MODE AND
FREE MODE
Holding Option and pressing C# (Track/
Free) button toggles the active channel
between track and free mode.
(Blinking White) TRACK MODE
means the active channel will set
its base frequency to the measured
frequency of “Osc In”. If the “Osc In”
signal is removed, the last measured
frequency will simply be held
indefinitely. When in page 1 view
(“Display” key unlit while holding
Option), H1 will display the closest note
tracked from “Osc In” on the key pad
with a pulsating white/yellow light.
(Solid Yellow) FREE MODE
means the active channel will set
its base frequency to a C 65.41Hz. So if
the unit is in NORMAL MODE and
Channel A is selected and it’s base
interval is set to “C” (first button
selected) than that channel will run at
65.41Hz.
!If in either of the CHORD
MODES, and FREE is selected, Channel
A CV In will provide the pitch basis for
both channels. That is to say, the root of
the chord can be either the pitch of Osc
In (Track) or based on CV A In (Free).
When in page 1 view (“Display” key
unlit while holding Option), H1 will
display the applicable note interval
derived from the CV input on the key
pad with a pulsating white/yellow light.
© 2023 Weston Precision Audio
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USING H1 - QUANTIZING
When in NORMAL MODE, the incoming
CV for each channel can be quantized.
The three options are 12T, uT, and Off
and are selected by holding Option and
pressing the applicable button 12T, uT,
or Off.
12T: This is normal 12 equally-tempered
quantizing, meaning the voltage will be
quantized to the steps on a musical
keyboard (C, C#, D, etc..). Quantize
steps are enabled/disabled by pressing
the buttons in page 2 view as shown on
the left of this page.
uT: The voltage will be quantized to 24
steps or “micro tuning” intervals.
Quantize steps are enabled/disabled in
the same way as 12T quantizing, but
since there are 24 steps, they are
displayed in 2 pages. For micro-tuning
quantization, alternate between steps
1-12 and 13-24 by pressing Option +
Octave Up.
Off: The voltage will not be quantized
at all and trigger in will be ignored. In
this mode, a channel in FREE MODE will
act just like an a regular analog VCO.
Trig In: Holding option and pressing D
(Trig In) toggles trigger in on or off for
the active channel. If Trig In is enabled,
the quantizer will only change to the
next enabled quantize step if a trigger in
is seen. This is useful when feeding a
random or semi-random voltage like an
LFO to the CV In but you would like the
notes to only change in sync with your
sequencer etc…
CV2: When in NORMAL MODE, the
CV2 Input can also be used to transpose
the base interval of the selected
channel. This feature is toggled on and
off by holding Option and pressing C
(CV2). H1 always quantizes CV2 to
12TET quantizing. When in CHORD
MODE, the CV2 input can be used to
transpose the active chord up or down
using a CV. It is toggled on or off in the
same manner as in NORMAL MODE.
When in CHORD MODE, CV1 is
always quantized to 12TET and
can be used to select the active chord
slot using a CV. CV2 is ignored in
CHORD MODE.
USING H1 - SYNC
In either CHORD or NORMAL MODE,
each channel’s oscillator can be soft-
synced (reversing sync) by 2 different
source signal options. This is selected by
pressing Option + G (Sync). The 3
modes for sync are as follows:
Sync off. No soft sync for this
channel.
Channel is sync’d at the frequency
of the signal input to “Osc In”
Channel is sync’d at the frequency
of the other channel (e.g. Channel
A is sync’d at Channel B’s frequency).
© 2023 Weston Precision Audio
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USING H1 - DETUNE
Each channel’s oscillator can be
detuned + or - 1 whole half tone. If
detune is disabled, the channel should
stay in tune to normal 440Hz A musical
tuning to within a cent or 2, but
sometimes having a fine tune is called
for, especially when using H1 to
“double” or “triple” a signal by mixing
copies of slightly detuned versions of the
original signal together for rich phasing
effects. Detune is toggled enabled/
disabled for the active channel by
pressing Option + A (Detune):
Detune disabled and detune knob
has no effect.
Detune is enabled. Turn the
detune knob to control amount. If
you have switched active channels
and adjusted the knob and then
switched channels back again, detune
knob is locked until it is moved again.
Detune information is stored when unit is
power cycled.
© 2023 Weston Precision Audio
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-12V Node

USING H1 - MIX PAD
The Mix output of H1 has a selectable
gain of either 1 or -9dB. Turning the
-9db “Mix Pad” option on is
accomplished by pressing Option + B
(Mix Pad):
Mix Pad is disabled and Mix
output stage has a gain of 1.
!Mix Pad is enabled and Mix
output stage has a gain of -9dB.
USING H1 - OCTAVE CONTROL
The octave + and - buttons control the
octave for selected channel. When in
CHORD MODE, the octave information
for that chord is saved with the chord.
The LED on the Oct + and Oct - buttons
indicate the octave status as follows:
No octave shift for this channel.
Octave shifted by 1.
Octave shifted by 2 or 3.
The octave control has a max adjustment
of + or - 3 octaves.
USING H1 - TUNER MODE
H1 also has a tuner mode, which can be
accessed by holding Option and
pressing the middle of the lower buttons
(The “F” key). Once in tuner mode, H1
will show the closest chromatic note that
Osc in is tuned to (C, C#, D, etc..) on
the keypad, and will show the fine
tuning difference on the octave + and
octave - keys (where + means sharp,
and - means flat).
At tuning errors of 8 cents or more, the
octave keys will blink yellow, sharp or
flat. As the tuning is improved, the
octave keys will blink white, then blink
slower white. When the signal present at
Osc In is tuned to within 2 cents of the
closest chromatic note, both octave keys
will light up solid white.
When in tuning mode, H1 will set
Channel A and B oscillators to 1Hz so
that it is easy to monitor the Osc In
signal through the mixer by ear during
tuning.
Tuner mode is exited the same way it is
entered: Holding Option and hitting the
“F” key.
© 2023 Weston Precision Audio
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APPENDIX: UPDATING FIRMWARE
The firmware of H1 can be user updated
fairly easily. In the even that a new
firmware is available from Weston
Precision Audio, the update procedure is
as follows:
1) Download the firmware (.UF2) file.
2) Take H1 out of your rack if not
already, and make sure it is NOT
connected to the ribbon cable from your
case or power supply.
3) Connect a USB micro B cable to the
USB port on the bottom rear of H1.
4) While HOLDING the button shown
below, connect the other end of the USB
cord to your PC or Mac.
5) H1 should show up on your PC or
Mac like a thumb drive does, titled
“RP2040”. Simply drop the downloaded
*.UF2 file downloaded from Weston
Audio onto “RPI-RP2”. FW update is
now complete. Disconnect the USB
cable and re-rack the module.
FW UPDATE ADDENDUM FOR PRE
10004 SERIAL NUMBERS:
For H1 units with S/N earlier than
10004, the procedure for firmware
updating is identical to the one on the
left, but the button from step (4) is more
inboard and thus must be pressed with a
flat, non-conductive tool such as a
tongue depressor, plastic pen handle, or
popsicle stick. The locating of the
pre-10004 S/N unit’s button is shown
below:
© 2023 Weston Precision Audio
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REVISION HISTORY
03: Updated description of new key
illumination for track and free, and
detune behavior/key illumination based
on v1.0.7 FW update.
02: Corrected description of boot mount
device in FW update procedure.
Removed incorrect line about CVB input
not used in chord modes.
01: Initial release.
© 2023 Weston Precision Audio
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