flight of harmony The Sound Of Shadows User manual

Digital Delay Effect v3.0
Eurorack Module
Kit

Specications
Supply Voltage ±12VDC1
Supply Current (max draw @ ±12V & +5V)I+12V= 19mA I-12V= -15mA I+5V= 21mA
Supply Current (max draw @ ±12V)I+12V= 41mA I-12V= -15mA
Max. Input Voltage (@ ±12V) 10Vp-p
Max. Output Voltage (@ ±12V) 6Vp-p
Input & Ouput (I/O) coupling Direct2
Output Impedance 1kΩ
Control Voltage (CV) inputs ±Vsupply
CV input coupling Direct
CV input impedance 100kΩ
Number of pieces (nuts & washers of
pots & jacks not counted) 132
Kit Difculty Medium-advanced
1) Has been tested and performs well with supply voltages from ±9VDC to ±15VDC.
2) I/O jacks are direct-coupled. The Delay circuit itself is not. A DC signal at the input will be
available at the Clean, and Mix outputs, but not available at the delay output.
SoSv3-K v1.0 manual May. 2022 — p.1/16 www.ightofharmony.com

(1) Front Panel
(3) PCB- Main, Potentiometer, Jack
(3) Resistor Card
(1) Semiconductor Card
(1) Capacitor Card
(1) Hardware bag
(1) 9” ribbon cable
(1) 2x8 box header
(2) 2x8 IDC socket connector with strain relief
(2) M3x0.5 eurorack mounting screw
(2) M3 nylon washer
(1) 1x3 Right Angle (RA) pin header
(1) 2x3 0.235" post pin header
(1) 1x4 0.235" post pin header
(1) 1x6 0.235" post pin header
(1) 1x6 0.318" post pin header
(1) 1x7 0.318" post pin header
(1) 1x4 socket header
(2) 1x6 socket header
(1) 1x7 socket header
(2) Nylon PCB Standoff (long)
(2) Nylon PCB Standoff (short)
(2) 1x2 Shunt1(the +5V header shunts)
(1) Potentiometer bag
(2) A100k Potentiometer (Input, Insert)
(3) B100k Potentiometer
(5) Washer
(5) Nut
(5) Knob
(1) Jack bag
(7) 3.5mm TS jack
(7) Washer
(7) Nut
(1) Reference manual (this thing)
1) Shunt vs. jumper: A jumper is a means to route a signal across another signal when
it cannot be done directly by trace on the PCB, whereas a shunt is a means of
conguring/directing signal ow.
Contents
SoSv3-K v1.0 manual May. 2022 — p.2/16 www.ightofharmony.com

What is it?
The Sound of Shadows (SoS) is a voltage-controlled (VC) digital delay module
based around the PT2399 echo IC1from Princeton Technology – which was, by
the way, originally designed for Karaoke equipment.
As with all f(h) products, the SoS was engineered towards maximizing
functionality while keeping cost as low as possible. If some aspects of the unit
seem awkward, it is most likely due to this. The goal is to make unique, useful,
enjoyable, and affordable instruments, not just hoover2out your bank account.
And remember: every instrument has its quirks and unexpected aspects, so
RTFM3all the way through! Specic quirks are mentioned in the description of the
particular feature they apply to, so please read this through before emailing!
Feature summary:
• VC delay rate.
• VC feedback level.
• Signal input.
• Clean, Delayed, and Mix outputs.
• Feedback loop insert jack.
• Multiple units can be chained together via rear header.
• Chaining cable available separately.
1) Integrated Circuit
2) Hoover is a company that manufactures vacuum cleaners.
3) RTFM = Read The F*cking Manual!
Overview (taken from SoS-E manual)
level
DELAY
Input
Chain
Delay In
x -1
FEEDBACK
GAIN
Clean
out
Mix
out
Mix
Delay
out
Insert
jack
EXT
Sound of Shadows v3 owchart
Chain
Delay out
x -1
Chain
Insert In
g.1: Flow diagram.
SoSv3-K v1.0 manual May. 2022 — p.3/16 www.ightofharmony.com

Overview (cont.)
Controls
Rate: This controls the delay clock rate, which
in turn controls how fast the delay steps through
its memory array and thusly the amount of delay.
Clockwise rotation increases the rate (which
decreases the delay time), counter-clockwise
decreases the rate (which increases the delay time).
Feedback: Controls how much of the delayed
signal is fed back into the delay cell. Feedback is
what creates a reverberation or echo sound – multiple
repetitions of an acoustic event. Clockwise rotation
increases the amount fed back, and thus the number
of repeats, counter-clockwise decreases the amount.
The nominal operating area is between 6:00 and
9:00 during normal usage. More than this will set up
a self-propagating feedback cycle that will quickly
get out of hand.
Insert: This is the attenuator for the feedback loop insert jack. The jack is
situated between the delay cell output and the feedback cell input. The feedback
cell input is calibrated for the output of the delay cell, which is around 1.5Vp-p
maximum, and most standard signals inserted here will overload the feedback cell
unless attenuated, hence the Insert attenuator. Turn clockwise to increase the signal
level, counter-clockwise to attenuate.
When not using the Insert jack, it is recommended to keep this control turned
fully clockwise, to the maximum position. Otherwise, you are attenuating the output
of the delay cell, which will affect everything else further down the signal path.
Input: This is the input level control. Just like a volume knob – clockwise
increases level, counter-clockwise attenuates the signal level.
Mix: Um, yeah. Guess what this controls? The balance of the mixed signal
at the Mix output! Seriously, this controls the mix between the Clean and Delay
signals at the Mix jack, really!
g.2: Control knobs.
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Jacks
The jacks are grouped by the type and direction
(into or out of the module) of the relevant signal.
Signal in
Input: This is kind of important for a delay unit:
you need a signal to delay, or else they’re somewhat
dull effects. This is the jack where that signal is input
into the delay.
Insert: This is the feedback loop insert breakjack.
Inserting a plug here will disconnect the output of the
delay cell from the input of the feedback cell, with the
inserted signal now going directly to the feedback
gain cell.
One use for this is to insert an effect – or even another delay unit (yes, they
can be daisy-chained quite effectively) – into the feedback loop. To do this, patch
the Delay out into the desired effect, and the output of the effect into the Insert jack.
You may need to adjust the Insert level control (see above) for best sound.
CV in
Rate: Quirk warning: Rate CV behavior is inverted. Negative increases rate,
positive decreases. If that bugs you too much, just think of it as the delay CV input
and the issue magically disappears! Positive increases the delay, and negative
decreases the delay.
Feedback: This works normally, positive CV increases feedback, negative
decreases same.
Output
Clean: A buffered and inverted copy of the input signal.
Delay: The buffered & scaled output of the delay cell
Mix: A linear mix of the Clean and Delay signals, the balance of which is set
by the Mix control pot.
Overview (cont.)
g. 3: Jacks.

SoSv3-K v1.0 manual May. 2022 — p.6/16 www.ightofharmony.com
Chaining Header
The rear header is to chain two or more SoS together
for longer delay times, and other effects, without using up
the front jacks. There is one output and two possible inputs
(See g.1 for graphical locations of the connection points.):
Delay out: Buffered, inverted, delay signal output.
Delay In: Equivalent to the Input jack. Chained signal
is summed with input signal and sent directly to delay cell
with no attenuation (see following Chaining Delay Trimmer
section).
Insert in: Equivalent to using the Insert jack, but without breaking signal path.
Chained signal is summed with output of Delay and Insert, then sent through the
feedback gain cell before entering the delay circuit, allowing signal attenuation.
Chaining Delay Trimmer
During development, it was noticed that overdriving the delay input of
the second Sound of Shadows resulted in some delightfully horric mangling,
screeching, and generally cacophanous sounds. However, it could not be the
default because it also drove the output up to ±10V, risking damage to connected
modules. This trimmer is the compromise.
Want a dangerous, horrendous, mess? Turn it all the way down (counter-
clockwise). Want a safe, factory-friendly setting? Turn it all the way up (clockwise).
In between? Put it where you want it. To repeat, however, and in ofcially-legal-
sounding words4:
WARNING: USE AT YOUR OWN RISK. USE OF THIS FEATURE WILL CAUSE
OUTPUT LEVELS THAT ARE NOT COMPATIBLE WITH EURORACK STANDARDS
AND WILL DAMAGE SOME MODULES, AND MAY DAMAGE THE REST. FLIGHT
OF HARMONY CANNOT ACCEPT RESPONSIBILITY FOR ANY DAMAGE
CAUSED BY USE OF THIS FEATURE.
The Chaining Delay Trimmer only affects the chained signal connected to the
Delay In pin and has no effect on unchained devices.
4) >A.K.A.: Royal Capslock
Overview (cont.)
g. 4: Rear chaining
header

SoSv3-K v1.0 manual May. 2022 — p.7/16 www.ightofharmony.com
Power
The power connector header is a
2x8/16-pin shrouded box header which
accepts the standard Doepfer power
cable. This header style is polarized,
meaning the connector can only be
inserted one way, to prevent connecting
the power backwards and damaging the
unit.
This assumes that you are using
either the supplied cable or one manufactured by Doepfer.
Looking at the rear of the module, the negative supply (red stripe) is on the
left, positive supply is on the right (see g.4).
+5V Source Selection
The Header marked “+5V” allows you to select whether the +5V is supplied
by the main +5V power bus or derived internally from the +12V supply. Set the
shunts in the position indicated by the PCB legend.
Stuff
A big thank you to those who have sent in suggestions and comments, keep
them coming!
Comments, inquiries, samples, suggestions, complaints to:
ight@ightofharmony.com
Drawings and designs ©2022 ight of harmony, LLC.
http://www.ightofharmony.com
By the way, the cover art is a an exercise I did in art class decades ago. One of those where you make gestures
with your hand and try to draw them on a pad of paper without looking at the paper, only at your hand. Then you
work on it in charcoal afterward and pretend it's real art. I even had to give it a title: "The Guarding Dark".
But hey, it's got shadows so it works for this. Don't judge me.
We are tomorrow’s shadows...
Overview (cont.)
g. 5: Power connections.

SoSv3-K v1.0 manual May. 2022 — p.8/16 www.ightofharmony.com
Kit Notes
Static Discharge Warning
Some pieces in this kit are static-sensitive and can easily be destroyed by
Electrostatic discharge (ESD). Make sure to discharge yourself and your work
surface while handling components from the semiconductor card.
How to safely discharge static: Use an ESD wrist strap and work mat. Do
not just connect everything directly to ground; that just creates a low-resistance
path for large currents to discharge through and will cause damage if the static-
sensitive component is in the path. ESD wrist straps have a high resistance built
in to safely limit the amount of current to below destructive levels. Keep in mind:
current does the damage, voltage creates the path for current to ow through.
Tools
• Soldering iron with ne tip
• Solder
• Fine-tip tweezers
• Nut drivers/sockets/wrenches:
• 8mm (Jack nuts)
• 10mm (potentiometer nuts)
• Pliers or vise (for closing ribbon cable power connector)
Skills
This kit assumes that you have a basic understanding of electronics, electronic
components, and soldering and assembling electronics. Note that this kit is almost
entirely Surface Mount Technology (SMT), so the assumption is that you understand
how to work with Surface Mount Devices (SMD) and have some experience.
This doesn't mean that you're completely on your own, just that I'm not going
to hold your hand1. Below are a few things to help get you started. Feel free to
ignore them.
Assembly Tips
• For the SMD, use the smallest soldering iron tip that you have. My favorite is
the Weller ETR (g. 6). (Not an endorsement, nor do I get anything from it, it's
just a good reference point.)
1) For many reasons, but two in particular: First, I'd have to leave my house, and I hate doing that.
Second, it's really hard to solder with only one hand.

SoSv3-K v1.0 manual May. 2022 — p.9/16 www.ightofharmony.com
• Good, ne-tip tweezers are a must. The Wiha 4b and 7a tweezers are great2.
• One helpful trick for soldering SMD with wire solder is to pre-solder one pad
for each component location. Next, hold the component in place and touch
your soldering iron tip to the pre-soldered pad to reow the solder. Then you
can solder the other side normally.
• Flux is your friend. Use ux. Water-soluble ux is best for a clean nish, but
you have to make sure to get it all off when done, as it can corrode the joint
and some uxes may also be capacitive. You can also use no-clean ux.
• Smallest rst. Solder the components in increasing order of size.
• Minimize heat exposure. Heat destroys components, and SMD are particularly
sensitive because they have less mass to distribute the heat. Flux helps with
this too.
• Use the face plate to line up the potentiometers and jacks before soldering;
much easier than resoldering them to line them up correctly afterward.
• Headers: The easiest way to align headers is to plug the related pin and
socket headers together, insert them into the circuit boards, then solder. A
rubber band — or even some tape — around the boards works to hold them
in place if you don't have some small clamps.
Help
If you're still having problems, email me! I am always happy to help. When
emailing, please include high-resolution pictures of your circuit boards.
Most of the troubleshooting requests I have received were solved by zooming
in and closely examining the pictures. Cold solder joints are sneaky and hard to
spot if you haven't dealt with them before. A cold solder joint is where the solder
doesn't adhere to both the pad and the component lead, and just owed around
one of them without making contact. They happen, and they suck, but they're easy
xes once you nd them.
2) IMO, their 5abb were the best, but they discontinued them so FML. No, you can't have mine.
Kit Notes (cont.)
Narrow Screwdriver
Cat. A B C
No. in. mm in. mm in. mm
ETR 0.062 1.60 0.044 1.12 0.625 15.90
A
B
C
g.6: Weller ETR soldering tip

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PCB Assembled View

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SMD Reference

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Exploded View
LONG
SHORT

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Control & Jack Reference
B100k
A100k
B100k
A100k B100k
B100k
A100k
B100k
A100k B100k

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Power Cable Assembly
Triangle indicates
location of red stripe.

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IC Orientation
Diode Orientation
Capacitor Orientation
Line/Slope Line/Slope
Pin 1
Miscellaneous
(OR) LINE
LINE

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