µRings SE
Eurorack Module
TD-URSE-B
Designed by Daniel & Michael Gilbert of Tall Dog
Electronics in Western Massachusettstall-dog.com | urings-se.com
Based on the Rings module designed by Olivier Gillet of
Mutable Instruments
mutable-instruments.net
Manufactured by Elecrow in Shenzhen, China
elecrow.com
Assembled at Rust Temple in Easthampton, MA
rusttemple.today

cba
Licensed under Creative Commons
Attribution-ShareAlike 4.0 International
creativecommons.org/licenses/by-sa/4.0
Source materials are available on GitHub
github.com/loglow/uRings_SE

Contents2About................................................................................................ 3
Included Parts............................................................................... 3History.............................................................................................. 4
Warranty......................................................................................... 5
Polyphony Selection	����������������������������������������������������������������� 6
Resonator Selection	������������������������������������������������������������������ 7
Making Connections	������������������������������������������������������������������ 9
Front Panel...................................................................................11
Calibration....................................................................................14
Firmware Warnings..................................................................15
Firmware Update.......................................................................16
Serial Programming.................................................................17
JTAG Programming...................................................................18
Documentation..........................................................................19
CC BY-SA 4.0.................................................................................20
Support..........................................................................................21
Who We Are..................................................................................21

About3

Rings is a resonator, transforming unpitched excitations(clicks, bursts, etc.) into full-bodied pitched sounds.
Rings models the bar, the tube, or the strings that you
can make vibrate by providing an external signal.
This redesigned µRings SE (Special Edition) is a newrevision of Rings that miniaturizes the module from
14HP to 8HP and redesigns its front panel layout.
µRings SE remains fully compatible with future
upstream Rings firmware upgrades and any otheralternate firmwares that are compliant with thestandard Rings design.

Included PartsµRings SE includes a standard 16-pin to 10-pin Eurorack
power cable and two sets of mounting screws for racks/
enclosures with either M2.5 or M3 threads.
The TD-URSE-B/B variant has a matte black front panel
with gold markings made from FR-4 (glass-reinforced
epoxy laminate) material. The included mounting
screws are black.
The TD-URSE-B/S variant has a satin silver front panel
with black markings made from anodized aluminummaterial via the Metalphoto process. The included
mounting screws are silver.

History

4

The original Rings (mutable-instruments.net/modules/rings) was designed by Olivier Gillet of
Mutable Instruments (mutable-instruments.net/about) under a CC BY-SA 3.0 (creativecommons.org/licenses/by-sa/3.0) license. Rings is available as a 14HP
Eurorack module.
Source: github.com/pichenettes/eurorackWarranty

5This product is covered under warranty for one year
following the date of purchase as indicated on theoriginal sales receipt. This warranty covers any defectin the manufacturing of this product. This warranty
does not cover any damage or malfunction caused
by incorrect use—such as, but not limited to, power
cables connected backwards, excessive voltage levels,
exposure to extreme temperature or moisture levels,
physical damage due to impact, or any aftermarket
physical or electrical modifications or repairs.
This warranty covers either repair or replacement,
at our sole discretion. This repair or replacement issubject to verification of the defect or malfunction andproof of purchase as confirmed by showing the model
number on an original dated sales receipt. Shippingand handling fees are to be paid for by the customer.
Please contact support@tall-dog.com for a return
authorization prior to shipping anything to us. Please
understand that we will not be able to service units
under warranty that have been modified or previously
repaired by the customer or a third party.

Polyphony Selection

6Rings operation is governed by two settings controlled
by buttons located near the center of the module: thePOLY button and the MODE button. Pressing either
button cycles between three states. The current state ofeach setting is indicated by the color of its associatedLED: green, amber, or red.
The POLY button selects the polyphony of the module:
LED ColorNotes

Green

1

Amber

2

Red

4

Enabling four note polyphony doesn’t mean that four
CV input jacks will magically appear on the module, butsimply that four notes played in sequence will nicely
overlap without cutting off each other’s tails.
To play chords, you will need to strum the moduleby playing a rapid sequence of notes—something
you might have already encountered with the Braids
module’s PLUK model.
Note that Rings might reduce the number of harmonics
in the generated signals to cope with higher polyphonysettings.

Resonator Selection

7

The MODE button selects from the three available typesof resonators. They are:Modal Resonator (Green)
Modal synthesis works by simulating the phenomenaof resonance at play in vibrating structures, that is to
say the way a string or plate (for instance) will absorb
certain frequencies while it will ring at some otherfrequencies, called the modes.
When we pluck a string, strike a drum or blow in a tube,
the short burst of energy of the blow/impact contains
many frequencies. Some of these fall outside of themodes, and are absorbed. Some of these excite themodes, producing a stable, pitched sound. Each mode
corresponds to a harmonic or partial in the spectrum of
the sound, and is modeled by a band-pass filter.
The Q factor of the filter determines how sustained theoscillations are of the corresponding partial. Various
materials or structures are characterized by different
relationships between the frequencies of their modes,
which Rings recreates.

Resonator Selection Cont’d8

Sympathetic Strings (Amber)Some interesting string instruments (such as the sitar orsarod) make use of strings that are not directly struck/
plucked by the musician, but which are just responding
to the vibration of other strings, and add extra overtones
or undertones.
Rings simulates this phenomenon with a bunch of virtual
strings (made with comb filters) allowing the addition ofextra tones to an incoming audio signal. The tuning ratio
between these strings can be altered.

Modulated/Inharmonic String (Red)This last method is perhaps the most familiar, since it’sbased on the extended Karplus-Strong method: theexcitation signal is sent to a comb filter with an absorption
filter, simulating the multiple reflection of a wave
propagating on a string and being absorbed at its ends.
However, to bring more variety to the sound, Rings
adds three extra ingredients to this classic: a delaycompensated all-pole absorption filter creating moredrastic plucking effects, delay time modulation emulating
the sound of instruments with a curved bridge (likethe sitar or tanpura), and all-pass filters in the delay
loop, shifting the position of the partials and recreating
the tension of piano strings or completely bonkers
inharmonic timbres.

Making Connections

9

Ideally, Rings would need three input signals:
1. A trigger signal on the STRUM input, which indicatesthat the currently playing note should fade away,
and that a new note is starting.
2. A CV signal on the V/OCT input, which controls thefrequency of the note.
3. An audio signal on the IN input, which will hit, strikeor caress the resonator.
Because it might not always be possible to get thesethree signals in your setup, Rings makes the following
assumptions:
1. If nothing is patched to the IN audio input, themodule will synthesize an excitation signal
whenever a note is strummed. This excitation signal
is either a low-pass filtered pulse or a burst of noise,depending on the resonator type.
2. If nothing is patched to the STRUM audio input, themodule will determine that a new string should bestrummed either by:●● Detecting note changes on the V/OCT input, or●● Detecting sharp transients within the IN audio
signal if nothing is patched to the V/OCT input.

Making Connections Cont’d

10

If there’s one take-home message from this:You can play Rings perfectly with just one CV output
taken from a sequencer or sample & hold module!
The note changes on the CV input will be interpreted asnote changes and the module will produce a suitable
excitation signal internally for these note changes tobe heard.

Front Panel

11

FREQ — Coarse frequency, adjusted by semitoneincrements. This control spans 5 octaves. Note that
the FREQ CV input is normalized to 1⁄12 V, allowing its
attenuverter to be used as a fine frequency control
when no patch cable is inserted.
STRUCT — Harmonic structure. With the modal
resonator, this parameter controls the frequency ratio
between partials (and by doing so, the perceived
structure—plate, bar, string). With the sympathetic
string resonator, this parameter controls the set offrequency ratios between all strings (with virtualnotches at octaves or fifths). Finally, with themodulated/inharmonic string resonator, this parameter
controls the amount of modulation and detuning of
the partials.
BRIGHT — Brightness. Adjusts the level of higher
harmonics in the signal, by the simultaneous action of alow-pass filter on the exciter signal (closed at 8 o’clock,fully open at 12 o’clock), and the damping filter (or Q
factor of the higher modes) on the rest of the courseof the potentiometer. Low values simulate materials
like wood or nylon. High values simulate materials likeglass or steel.
DAMP — Damping. Controls the decay time of thesound, from less than 100 ms to about 10 seconds.

Front Panel Cont’d12

POS — Excitation position. Controls on which point of
the string/surface the excitation is applied. Applying
the excitation right in the middle of the surface willcause, by symmetry, the even harmonics to cancel
each other, resulting in a hollow sound reminiscent ofa square wave. This setting will remind you of the PWM
control on a square oscillator, or of the comb-filtering
effect of a phaser.
POLY — Polyphony setting. Selects between
monophonic, duophonic and quadriphonic operation.
MODE — Resonator type. Selects between modal,
sympathetic and string resonators.
STRUM — Strumming trigger input, for polyphonicoperation. Whenever a trigger is received on this input,
the module freezes the currently playing voice and lets
it decay, and starts a note on the next voice. Normalized
to a step detector on the V/OCT input and a transient
detector on the IN input.
IN — Audio input for the excitation signal. Modular
levels are expected. Normalized to a pulse/burst
generator that reacts to note changes on the V/OCTinput.
V/OCT — CV input. Controls the main frequency of theresonator.

Front Panel Cont’d13

ODD and EVEN — Odd and even audio outputs:●● In monophonic mode, these two outputs carry twocomplementary components of the signal (odd andeven numbered partials with the modal resonator,
dephased components due to picking position andpickup placement with the string resonators).
●● In polyphonic mode, the signal is split into odd andeven numbered strings/plates.
●● Note that you need to insert a jack into each outputto split the signals. When only one jack is inserted,
both signals are mixed together.

Calibration

14

The module is factory-calibrated using precisionvoltage sources. Follow this procedure only if you wantto compensate for inaccuracies in your CV sources, or if
your module has lost its calibration settings following a
fault or the installation of alternative firmware.
To calibrate the unit:
1. Disconnect all CV inputs.
2. Connect the note CV output of a well-calibrated
keyboard interface or MIDI-CV converter to theV/OCT input jack.
3. Connect a patch cable to the FREQ CV input. Leave
the other end of the cable unplugged.
4. Press and hold both the POLY and MODE buttons fortwo seconds. The POLY LED will blink amber.
5. Play a C2 note, or send a 1V signal from your CV
source.
6. Press the POLY button. The MODE LED will blinkamber.
7. Play a C4 note, or send a 3V signal from your CV
source.
8. Press the POLY button.
If calibration was successful, the module will return toits normal state. Otherwise, both LEDs will blink red fora few seconds.

Firmware Warnings

15

Before starting the audio firmware update procedure,please double-check the following:●● Make sure that no additional sound (such as email
notification sounds, background music, etc.) fromyour computer will be played during the procedure.
●● Make sure that your speakers/monitors are muted
or not connected to your audio interface—the noises
emitted during the procedure are aggressive andcan harm your hearing.
●● On non-studio audio equipment (for example theline output from a desktop computer), you might
have to turn up the volume to the maximum.

Firmware Update

16Unplug all inputs/outputs from the module. Connect
the output of your audio interface or sound card tothe IN input jack. Set the FREQ knob to 12 o’clock.
Power on your modular system while holding the POLY
button, then release. Both LEDs should blink amber.
When you are all set, play the firmware update file intothe module. While the module receives data, the POLY
LED will blink green, and the MODE LED will monitor
the signal level. Signal reception is optimal when theMODE LED is green or yellow. Try adjusting the FREQ
knob to change gain. The module will periodicallypause to write data to its permanent memory. BothLEDs will be amber during these pauses. When theend of the audio file is reached, the module willautomatically restart. If it doesn’t restart, please retry
the procedure.
If the signal level is too weak, the LEDs will blink red
in an alternating pattern. Press the POLY button andretry with a higher gain. If this doesn’t help, try theprocedure from a different computer or audio interface,and make sure that no other equipment (such as anequalizer or FX processor) is inserted in the signalchain.

Serial Programming

17

The module can also be programmed using a serial
data connection. This is most easily accomplished byusing a USB-to-serial chip such as the popular FT232R
which can be found in many standalone breakout
boards and cables, including the FTDI TTL-232R-3V3 aswell as various equivalents from Adafruit, SparkFun,and others. Data signals should be at 3.3V levels.
The serial connection should be hooked up to thewhite shrouded 6-pin header labeled FTDI (H6) on themodule’s PCB. This is a JST-XH header that works very
well with the 0.1″ pitch female connectors that are
frequently found on these cables. Only pins 1 (GND),4 (RX), and 5 (TX) are used, and the location of pin 1 isclosest to the top of the board. Power must be supplied
separately via a Eurorack power cable connected to thePOWER (H7) header.
To prepare the processor for serial programming:
1. Power-on the module.
2. Press and hold both the BOOT (S1) and RESET (S2)buttons at the same time.
3. Release the RESET button.
4. Wait a moment, then release the BOOT button.
The processor is now ready to be programmed.

JTAG Programming

18The module can also be programmed using a JTAG
programmer connected to the black shrouded header
labeled JTAG (H5) on the module’s PCB. Power mustbe supplied separately via a Eurorack power cableconnected to the POWER (H7) header.
An example of this kind of programmer is the Olimex
ARM-USB-OCD. Their ARM-JTAG-20-10 adapter is also
necessary in order to accommodate the module’s
miniature 0.05″ pitch 10-pin header.
No additional steps are necessary to prepare themodule for programming via this method.
If you are interested in serial or JTAG programming,
please explore the Vagrant environment for Mutable
Instruments modules hacking which can be found at
github.com/pichenettes/mutable-dev-environment
Other programming resources can be found at forum.
mutable-instruments.net/t/4336 (Mac Tutorial: How
to compile and upload the firmware of MIs eurorackmodules) and at medium.com/music-thing-modularnotes/a08173cec317 (How to get started writing yourown firmware for Mutable Instruments Clouds), the latterof which was written for the Clouds module but is also
applicable to Rings.

Documentation

19

Much of the information in this manual was created byOlivier Gillet of Mutable Instruments and released under
the CC BY-SA 3.0 license.
Modifications and additions to this material werecreated by Tall Dog and released under the compatible
CC BY-SA 4.0 license.
For an overview of the implications and terms of theselicenses, please read the following page.

CC BY-SA 4.0

20

This is a human-readable summary of (and not asubstitute for) the license, which can be found atcreativecommons.org/licenses/by-sa/4.0/legalcode

You are free to:●● Share — copy and redistribute the material in any
medium or format.
●● Adapt — remix, transform, and build upon thematerial for any purpose, even commercially.

Under the following terms:●● Attribution — You must give appropriate credit,
provide a link to the license, and indicate if changes
were made. You may do so in any reasonable
manner, but not in any way that suggests thelicensor endorses you or your use.
●● ShareAlike — If you remix, transform, or build uponthe material, you must distribute your contributions
under the same license as the original.
●● No additional restrictions — You may not apply
legal terms or technological measures that legally
restrict others from doing anything the licensepermits.

Support

21

For all support inquiries, please send an email tosupport@tall-dog.com

Who We Are
Tall Dog Electronics is located in the Pioneer Valley
region of Western Massachusetts. Tall Dog has primarily
focused on producing a variety of breakout boards for
the Teensy microprocessor development platform andconducts the majority of its business via the Tindie
marketplace. Tall Dog released their first Eurorack
module, µBraids SE, in late 2017.
Michael Gilbert is a composer, recording artist, andteacher of electronic music, for over 40 years. Hismusic is a creative mix of electronic, jazz, world, andcontemporary classical idioms, and is available on 9
albums of original work as Michael William Gilbert. Themusic has featured Adam Holzman, Mark Walker, Peter
Kaukonen, David Moss, and Tony Vacca. He has also
designed and built electronic music equipment, using
it in his own studio and making it available to othermusicians.
Daniel Gilbert is a designer and engineer with abackground in film, photography, and animation. After
graduating from Hampshire College he spent the next
several years working in the Los Angeles film industry.
He now resides in Easthampton, Massachusetts, where
he designs, builds, and distributes Tall Dog products.

µRings SE User Manual
Revised 2018-11-05
Documentation CC BY-SA 4.0