Fairfield Circuitry Shallow Water User manual

TECHNICALS
- true bypass
- input impedance 1MΩ
- output impedance 2kΩ
- power supply 9 to 9.6 VDC
- current draw 40 mA max.
PHYSICALS
- 1/4” mono input/output jacks
- 2.1mm DC connector
- 4.7” x 3.8” enclosure dimensions
NOTES ON POWERING
Shallow Water was designed to operate using
your typical centre negative, regulated 9-9.6
VDC power supply. The pedal is protected
against reversed polarity and overvoltage
conditions. Always check your power supply
for proper voltage and polarity before con-
necting. There is no battery connection inside
the pedal.
ABSTRACT
Shallow Water’s essence could be
characterized as uncertain, subtle
and nostalgic.
Practically, this describes an
effect built around your typical
analogue chorus/vibrato circuit
wherein the signal is delayed by
a few dozen milliseconds using
a bucket brigade device. Another
signal then modulates this delay
time to create changes in pitch,
called vibrato. Chorus is achieved
by mixing the original signal with
the delayed signal, creating the
moving comb lters that tickle
our ears and feather our bangs.
Still, major differences can be
noticed when studying the k-eld
modulator’s architecture. The most
striking are how the delay time
is modulated in a random fashion
and how the recovery lter moves
in relation to the input signal.
Both these differences place
Shallow Water in a category of its
own, appropriately called k-eld
modulators.
As the present gets lost, the
future becomes the past.
PSEUDO RANDOM GENERATOR
The random quality of the modulation begins in a simple pro-
gram residing on a microcontroller. Its output resembles steps
of random voltages, seperated by random time intervals. The
RATE control effectively sets the overall range of these time
intervals.
INTEGRATOR AND DEPTH
These random stepped voltages are processed through a lter/
integrator, giving control over the slope at which the steps
will reach their new values. As DAMP is increased, the random
steps become slow and sluggish, instead of sharp and abrubt.
DEPTH denes the amount of modulation that will be used to
modulate the time delay of our input signal. There is a strong
interaction between all three controls affecting modulation; that
is, RATE, DAMP and DEPTH.
ENVELOPE FOLLOWER AND RECOVERY FILTER
Once the input signal has passed through the delay line, a
recovery lter and some kind of gate is necessary to remove
unwanted noise generated by the bucket brigade device. To
achieve this, the input’s envelope is followed and used to mod-
ulate the frequency of a low pass lter. The amount of envelope
is set by the LPG control, yielding bouncy, lo- responses to
quick and snappy gate-like behaviours.
EXTENDED WARRANTY
Faireld Circuitry will repair or replace any
malfunctioning product for a period of 2
years after purchase date. Problems resulting
from modications or misuse may cancel this
warranty. The owner will cover all shipping
expenses. This warranty applies only to origi-
nal owner of the product. Proof of purchase
might be required.
In short, the best thing to do is to contact us
as soon as possible with a description of the
symptoms, even if the warranty is expired.
SHALLOW WATER
K-Field Modulator
ENVELOPE
FOLLOWER
DELAY
LINE
ANTI-ALIASING
FILTER
DAMP
NOISE FILTER
+
INTEGRATOR
RATE
PSEUDO
RANDOM
GENERATOR
VOLTAGE
CONTROLLED
CLOCK
DRIVER
VOLUME
MIX
OUT
IN
VOLTAGE
CONTROLLED
LOW PASS
FILTER
LPF
DEPTH

UNIQUE & ROBUST
MADE IN HULL, QUÉBEC
FAIRFIELDCIRCUITRY.COM
CONTROLS
RATE
The RATE control adjusts the time
intervals at which the random pitch
uctuations occur. From rare to
nervous, the range is quite wide. At
high RATE and DAMP settings, the
quick variations have trouble pass-
ing through the swampy lter and
integrator, effectively reducing per-
ceived modulation. This is normal. The
interaction between these two knobs
is particular and needs to be tamed
through experimentation.
DAMP
The DAMP control affects the slope of
the modulating signal. At its minimum,
the pitch modulations are quick and
sudden; the random changes in modu-
lation voltage are almost instantane-
ous. Increasing DAMP will elongate
and soften the modulation. At high
DAMP settings, the changes become so
slow that they are not heard as pitch
modulations. To hear the changes,
some dry mix needs to be applied.
Then, the slow movement of the delay
time can be heard as chorus.
DEPTH
The DEPTH knob adjusts the intensity
of the modulation. The interaction
between all three modulation controls
is noticeable. The range of modulation
is focused towards subtle variations.
Adjust to taste, though less is more.
MORE CONTROL INSIDE
BOOST AND PAD
There are 2 jumpers at the input stage to match
your input signal’s level and impedance. By
default, BOOST is on, PAD is off; a typical set-
ting for high impedance, low output signals like a
guitar’s single coil pickups. If the user nds there
is too much distortion at the input stage, moving
the BOOST jumper to its off position will reduce
overall gain by 6 dB. If the signal source is line-
level, the PAD can be set to its on position, giving
another 6 dB of gain reduction while also reducing
the input impedance by a factor of 10.
LPG ADJUST
The recovery lter’s lowest frequency can be ad-
justed, to ne tune the way it will react to incom-
ing signals. Lowering this frequency emphasises
the action of the low pass lter, effectively raising
the threshold of sensitivity. Adjustment should be
made with the following settings: MIX full wet,
LPG minimum, DEPTH minimum. While listening to
a signal going through the pedal, you’ll hear the
effect of the recovery lter at its resting state.
Carefully turn the trimpot labelled LPG adjust,
clockwise to raise the lter’s frequency, counter-
clockwise to lower. Be very careful, adjustments
should be minimal as the trimpot is very sensitive.
After each adjustment, LPG should be turned up
momentarily to listen at the envelope’s response
to the incoming signal.
LPG
The LPG control adjusts the level of the envelope go-
ing to the low pass lter and gate circuit. At lower
levels the signal will be darker, choke subtle notes
and reduce sustain. At higher settings, the sound will
be brighter, have more sustain and might reveal some
noise produced by the bucket brigade device.
MIX
The MIX control balances between the dry and wet
signal. When it’s full wet (clockwise) the effect is like
a vibrato. Chorus-type sounds are achieved by adding
some of the dry signal (counter clockwise).
VOLUME
The VOLUME knob controls the output volume. Unity is
around noon and beers around 5 at my place.
F A I R F I E L D C I R C U I T R Y
K F M 0 0 0
V O L U M E
M I X
D A M P
R A T E
D E P T H
L P G
plenty of output volume
rate of
change
modulation
slope
modulation
depth
dry/wet mix
envelope amount output
input
9 VDC