CH C1 Mono User manual

C1 Digital to Analog Controller
User Manual

Dear Client,
We are honored that you have chosen the CH C1 Digital to Analog Controller. Our team has put all his efforts into designing and
manufacturing this top uality versatile and future-proof product and is proud to present it to you. We hope your C1 will bring you
uncountable hours of emotion from your musical collection.
But before starting your musical journey, we kindly ask you to pay attention to the information contained in this manual. The C1,
as you will discover in the following pages, is a Swiss precision product designed for ultimate performance and flexibility. However,
reaching sonic excellence re uires your unit to be setup and operated correctly and this what this manual is all about. If you have
any uestions or re uire assistance, please don't hesitate to contact your authorized dealer.
We hope you will enjoy your C1 D/A Controller for many years.
The Concert has just begun...
Cossy F.
Heeb T.

FCC-Notice
Note: This e uipment has been tested and found to comply with the limits for a Class B digital device, pursuant to Part 15 of
the FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a residential
installation. This e uipment generates, uses and can radiate radio fre uency energy and, if not installed and used in
accordance with the instructions, may cause harmful interference to radio communications. However there is no guarantee that
interference will not occur in a particular installation.
If this e uipment does cause harmful interference to radio or television reception, which can be determined by turning the
e uipment off and on, the user is encouraged to try to correct the interference by one or more of the following measures:
•adjust or relocate the receiving antenna
•increase the separation between the e uipment and the receiver
•connect the e uipment into a mains outlet on a circuit different from that to which the receiver is connected
•consult the dealer or an experienced ratio/TV technician for help
Disposal – Environmental care
Directive 2002/96/EG of the European Parliament re uires consumer electro-technical appliances to be
disposed separately and have to be indicated with the following symbol. Should you dispose this
component please do so in conformity with local and global legal and environmental regulations and
according to best practices. We strongly encourage you to recycle any batteries used with this component.

Table of contents
1 Technical Highlights.............................................................................................................................................................. 8
1.1 Digital to analog conversion......................................................................................................................................... 9
1.1.1 Clock management............................................................................................................................................. 9
1.1.2 HiD processing engine......................................................................................................................................... 9
1.1.3 D/A conversion stage........................................................................................................................................ 10
1.1.4 Output stage.................................................................................................................................................... 10
1.1.5 Volume control capability.................................................................................................................................. 10
1.2 Mechanical construction............................................................................................................................................. 11
1.3 Modular architecture and slot-in boards...................................................................................................................... 11
1.3.1 Digital inputs and CH Link: DIGITAL_IN board.................................................................................................... 12
1.3.2 USB Audio inputs: USB_IN board option............................................................................................................. 12
1.3.3 Analog inputs: ANALOG_IN board option........................................................................................................... 12
1.3.4 External clock synchronization: SYNC_IO board option........................................................................................ 12
1.3.5 Ethernet streaming: NETWORK board option....................................................................................................... 13
1.4 Power supply............................................................................................................................................................ 13
1.4.1 Optional external power supply......................................................................................................................... 13
2 Before Use........................................................................................................................................................................ 14
2.1 Package content........................................................................................................................................................ 14
2.2 Safety notice............................................................................................................................................................. 14
2.3 User Manual............................................................................................................................................................. 15
2.4 Mains supply............................................................................................................................................................. 15
2.5 Transport and packaging............................................................................................................................................ 15
2.6 Cleaning................................................................................................................................................................... 16
2.7 Maintenance and service............................................................................................................................................ 16
3 Installation........................................................................................................................................................................ 17
3.1 Unpacking................................................................................................................................................................ 17
3.1.1 Removing the security screw.............................................................................................................................. 17
3.2 Positioning................................................................................................................................................................ 17
3.2.1 Unit position adjustment.................................................................................................................................... 17
3.2.2 Adjustment shaft covers.................................................................................................................................... 18
3.3 Connections............................................................................................................................................................... 19
3.3.1 CONTROL board................................................................................................................................................ 20
3.3.1.1 USB port.................................................................................................................................................. 21
3.3.1.2 Ethernet port........................................................................................................................................... 21
3.3.2 NETWORK board............................................................................................................................................... 21
3.3.2.1 USB port.................................................................................................................................................. 21
3.3.2.2 Ethernet port........................................................................................................................................... 21
3.3.3 DIGITAL_IN boards........................................................................................................................................... 21
3.3.3.1 Standard digital inputs............................................................................................................................. 22
3.3.3.2 CH Link digital audio interface.................................................................................................................. 22
3.3.4 USB_IN boards................................................................................................................................................. 22
3.3.4.1 Microsoft Windows configuration (XP, Vista, 7 and 8)..................................................................................23
3.3.5 ANALOG_IN boards.......................................................................................................................................... 23
3.3.6 SYNC_IO board................................................................................................................................................ 24
3.3.6.1 BNC clock input........................................................................................................................................ 24
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3.3.6.2 BNC clock outputs..................................................................................................................................... 25
3.3.7 Power cord receptacle and voltage selection....................................................................................................... 25
3.3.8 External power supply connector....................................................................................................................... 25
4 Operation.......................................................................................................................................................................... 26
4.1 Front panel controls................................................................................................................................................... 26
4.1.1 Front panel...................................................................................................................................................... 26
4.1.2 User control knob............................................................................................................................................. 26
4.2 Operating modes....................................................................................................................................................... 28
4.2.1 Normal mode................................................................................................................................................... 28
4.2.2 Shortcuts.......................................................................................................................................................... 29
4.2.3 Menu mode...................................................................................................................................................... 31
4.3 Configuration............................................................................................................................................................ 34
4.3.1 C1 configuration menu items............................................................................................................................. 35
4.3.1.1 AUDIO SETTING........................................................................................................................................ 35
4.3.1.2 DISPLAY SETTING...................................................................................................................................... 38
4.3.1.3 SHORTCUTS.............................................................................................................................................. 40
4.3.1.4 FACTORY SETTING..................................................................................................................................... 41
4.3.1.5 INSTALLED OPTIONS................................................................................................................................. 42
4.3.1.6 NETWORK................................................................................................................................................ 43
4.4 Remote control.......................................................................................................................................................... 44
4.4.1 Remote control operation.................................................................................................................................. 44
4.4.2 Changing the remote control batteries................................................................................................................ 45
4.5 Advanced clocking..................................................................................................................................................... 45
4.5.1 General clocking considerations......................................................................................................................... 45
4.5.2 Without SYNC_IO board.................................................................................................................................... 45
4.5.3 C1 D/A controller (with SYNC_IO board) + D1 SACD/CD drive (with SYNC_IO board)..........................................46
4.5.4 3x C1 D/A controllers + multichannel D1 drive (all with SYNC_IO board)............................................................47
4.5.5 C1 D/A controller + Computer (USB audio)........................................................................................................ 49
4.5.6 C1 D/A controller + Computer (Ethernet audio streaming)..................................................................................49
4.6 Returning to Factory defaults..................................................................................................................................... 50
5 Firmware update............................................................................................................................................................... 51
5.1 Introduction.............................................................................................................................................................. 51
5.2 Firmware Update procedure....................................................................................................................................... 51
5.2.1 Preparing the firmware image........................................................................................................................... 51
5.2.2 Updating the firmware (Firmware Update procedure)......................................................................................... 52
5.2.3 Emergency Firmware Update procedure............................................................................................................. 52
6 Troubleshooting................................................................................................................................................................. 54
7 Specifications..................................................................................................................................................................... 56
7.1 Specifications............................................................................................................................................................ 56
7.2 Dimensions............................................................................................................................................................... 58
7.3 Factory settings......................................................................................................................................................... 59
Rev 1.9 C1 User Manual 7

1 Technical Highlights
CH products are proudly designed and manufactured in Switzerland by CH Precision Sàrl. Our engineers have put all their know-
how into bringing you the C1, a top performances future-proof digital to analog (D/A) controller, based on slot-in boards and USB
flash-drive firmware update. In its base version the C1 is a four inputs D/A converter, with integrated preamplifier functions such
as source selection and volume control. Default configured C1 have one DIGITAL_IN board and a CONTROL board. Audio inputs on
each DIGITAL_IN board include three standard digital audio connectors (RCA coaxial S/PDIF, TOSLINK optical S/PDIF and XLR AES-
EBU) supporting S/PDIF encoded PCM up to 24bits/192kHz, as well as proprietary high definition CH Link interface, supporting
both I2S PCM (up to 32 bits/768kHz) and native DSD audio signal connection.
Optional boards allow to extend the functionality of the base version of the C1 D/A controller. By adding extra DIGITAL_IN boards
(a total of up to three input boards can be plugged in the unit), the C1 can be connected to even more standard digital sources.
Addition of optional USB_IN board and/or optional NETWORK Ethernet streaming board (replaces standard CONTROL board)
unleashes the full capabilities of the C1 as the ultimate high-resolution computer audio file player. On the other hand, ANALOG_IN
optional board will turn your C1 into a top uality preamplifier while offering single-ended RCA and balanced XLR analog inputs.
Finally, the SYNC_IO optional board provides advanced clock synchronization capabilities for use with external clock generators or
to enslave the D1 SACD/CD drive to the C1's Masterclock for zero-jitter connection.
C1 main components
(1) External power supply input. For X1 optional external power supply only
(2) Mains switch and power cord receptacle (on back panel)
(3) Adjustment shafts and screws
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(2)
(1)
(3)
(4)
(5)
(6)
(7)
(3)
(8)
(9)
(10)
(3)
(13)
(3)
(14)
(11)
(12)

(4) Power supply section
(5) Main power transformer
(6) Standby power transformer (ensures green mode Standby)
(7) Power supply regulation board
(8) AMOLED display (on front panel)
(9) Audio in, clock in/out, USB (firmware update) and RJ-45 (control/network) connectors (from slot-in boards). Analog ground to Earth jumper
(10) Slot-in boards (SYNC_IO, CONTROL/NETWORK, DIGITAL_IN/USB_IN/ ANALOG_IN)
(11) Main processing and control board
(12) Left channel DAC board
(13) Right channel DAC board
(14) Concentric push control knob
1.1 Digital to analog con ersion
The C1 D/A controller is built around a synchronous CH-HiD processing engine feeding two first grade factory-calibrated monaural
D/A conversion boards. The conversion stage is a linearized R2R topology, followed by a fully discrete output stage. The whole
purpose of this design is not only to reconstruct correct level information but also perfect timing, since it is the key element for
recreating nature-like immersion into a musical performance.
1.1.1 Clock management
The first re uirement to achieve perfect timing is that audio data are fed into the DAC chips synchronously to a jitter-free clock.
This is why two high-precision low-drift audio crystal clock oscillator (22.5792 MHz for 44.1 kHz multiples and 24.576 MHz for 48
kHz multiples) are located only a few cm from the DAC chips. The clocking section has its owns dedicated power supply fully
decoupled (complete galvanic isolation) from all noisy digital signals. This critical Masterclock signal is carried to the DAC chips in
LVDS (low-voltage differential signaling) form to avoid any cross-talk pollution.
In order to be synchronous to the incoming audio signal, these crystal oscillators can be fine tuned using a voltage controlled
feedback (VCXO), computed by a proprietary algorithm. Performances of this “digital phase-locked loop” (digital PLL) is jitter
rejection below 0.1 Hz, while fre uency tracking is achieved through sub 0.1 PPM correction steps. Phase alignment is also
guaranteed with a +/-2.5 us accuracy. When combined with matching CH D1 SACD/CD drive and optional synchronization boards
(or a computer source), the C1 can even be configured as the clock master, having the source (either CH D1 or computer) clock-
enslaved. In such configuration, the jitter is completely removed from the system.
1.1.2 HiD processing engine
After years of development in the high-end audio industry we came to the conclusion that the digital samples contained in the
original audio stream should remain untouched, only computing missing information between them to remove most of the burden
(and phase non-linearity) off the analog filtering stage. Compared to widely-used asynchronous sample rate conversion (ASRC),
synchronous up-sampling removes all harshness often found in digital players.
Rev 1.9 C1 User Manual 9

The 4.8GFLOPS DPS engine used for each channel performs several tasks, including synchronous up-sampling (to 705.6/768 kHz),
DSD to PCM conversion (for DSD layer playback of SACDs), volume control, resolution enhancement and linearity enhancement
(proprietary scrambling algorithm).
1.1.3 D/A con ersion stage
The digital to analog conversion stage of each channel is handled by four Burr-Brown PCM 1704 R2R chips.
While total harmonic distortion (THD) figure of top R2R conversion chips (such as PCM 1704 used in C1) is slightly less impressive
than those of Delta-Sigma technology based converters, their temporal behavior (on transient events which music is filled with) is
inherently better. The high fre uency behavior (above 20 kHz) is also much more accurate and free from modulation noise that
often disrupts treble speakers (tweeters), as high energy content into the 20 kHz -100 kHz band can not be handled properly by
most tweeters.
Combining four PCM 1704 the way it is done in the C1 enables improved THD figures compared to individual conversion chips and
to exploit their full output range (scrambling) which leads to an enhanced linearity, especially for small signal modulation (which is
common in the C1, especially when used as a preamplifier with volume control).
In order to achieve reproductive audio performances through our production, each chip used for a single channel should be
identical, including gain and offset. Unfortunately, tolerances on these parameter is rather loose. In order to avoid costly manual
component measurement and matching (or disparity of the audio performance of a production batch), we have introduced a fully
automated calibration process that is factory-performed, and can also be run by customer to keep top performances over time.
During this calibration process, the DSP sets several codes to each individual DAC chip, while a dedicated analog to digital converter
(ADC) measures the resulting voltage. The DSP is then able to compensate for any disparity across DAC chips on a DAC board.
1.1.4 Output stage
Each PCM 1704 chip outputs an analog current which reflects the digital code fed to the C1.
It is first converted by an ultra-fast current to voltage stage (I-V). The bandwidth of this stage has to be very wide, in order not to
distort (i.e. add harmonic distortion) the staircase shape of the sample-and-hold DAC chip output.
A fully discrete low-pass filter without feedback comes next, to smooth out the voltage signal without generating in-band phase
shift.
Finally, a differential output stage with high output current capability follows, driving single-ended 75 Ohm WBT nextgen RCA,
single-ended 50 Ohm BNC and fully-balanced Neutrik XLR connectors.
1.1.5 Volume control capability
The C1 can be used as a pure DAC (digital to analog converter) together with an analog preamplifier. But it can also be used as a
controller, directly feeding power amplifiers. In that case, it allows volume control in the range of -95.5 dB to +24.0 dB (with
0.5dB steps), with full muting capability when volume is turned lower than -95.5 dB. Positive gain (+0.5 dB to +24.0 dB) is only
possible when the incoming signal is lower than 0 dBFS (full scale). Otherwise, the C1 will automatically decrease the volume in
order to avoid any clipping. Left/right balance correction is also available in a +/- 6dB range (with 0.5dB steps).
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Volume control is achieved by a combination of analog attenuators and high resolution digital multiplication.
When the volume is set in the range -95.5 dB to -12.5 dB, a 12 dB analog attenuator in engaged, and the DSP attenuates (i.e.
multiply the audio sample in 32 bits floating point resolution) by [volume + 12 dB].
When the volume is set between -12.0 dB and -6.5 dB, a 6 dB analog attenuator in engaged, and the DSP attenuates by [volume
+ 6 dB].
When the volume is in the range -6 dB to 0dB, no analog attenuator is engaged, and the DSP attenuates by [volume].
When the volume is positive (i.e. +0.5 dB to +24.0 dB), no analog attenuator is engaged, and the DSP applies a positive gain
corresponding to [volume], whenever possible. If the DSP detects that the upcoming resulting samples will digitally clip (sample
value * volume > 0 dB full scale), it will soft clip this event and automatically decrease the volume to a value that will avoid
clipping in the future.
1.2 Mechanical construction
The C1 D/A controller is assembled from high- uality aluminum and steel elements with no visible screws on the front, top and
side panels. The front panel, base, side panels and top cover are machined from aluminum. The power supply is isolated from the
audio section in its own compartment to avoid any contamination of the audio circuits by noise radiated from the supply. Pin
assembly of all chassis elements provides smooth joints between elements while screws every 6cm ensures protection against
electromagnetic interferences. First class mechanical and chemical surface treatments provide the luxury finish of the C1.
Four steel feet support the unit. Each feet ends with a elastomer ring to sit on delicate surfaces but is also e uipped with a height
adjustable steel spike to fine tune unit positioning. Horizontal adjustment is done with the provided screwdriver through the four
adjustment shafts accessible from the top of the unit. In addition to providing convenient horizontal adjustment from the top of the
unit, the shafts also serve as vibration evacuation channels for any stacked unit. Special shaft covers are provided to interface with
the spikes of the stacked unit. Any vibration from the upper unit is transmitted by the shaft cover to the shaft and from the shaft to
the lower unit feet or spike, forming a privileged path for vibrations evacuation.
1.3 Modular architecture and slot-in boards
The C1 benefits from a fully modular architecture. It features separated sections for power-supply, front panel, computing +
signal/clocks routing + central host processor, slot-in boards and monaural conversion boards. This modular architecture combined
to the USB plug for all firmwares (MCU, DSPs and FPGAs) update allows for easy servicing and upgrade should one section become
faulty or obsolete.
The slot-in boards section consists in a vertically mounted mother board with optional boards plugged into it. Optional boards
provide audio functionality and connectivity to other e uipment. There are six types of slot-in boards:
•DIGITAL_IN: provides three standard digital audio input plus a proprietary CH-link input
•USB_IN : provides asynchronous USB audio (up to 24bits/192kHz) input. Computer is enslaved to the C1, sending audio
packets a a C1-specified rate
Rev 1.9 C1 User Manual 11

•ANALOG_IN: provides single-ended RCA and balanced XLR analog audio input
•SYNC_IO: provides advanced clock synchronization options (1 clock in, 2 clock out)
•CONTROL: provides a USB port for software upgrade and an Ethernet port for command
•NETWORK: optional board used to upgrade the CONTROL board slot. Provides a USB port for software upgrade and an
Ethernet port for high resolution audio streaming and command
There are five slots in the C1. Three of them can be populated with any combination of DIGITAL_IN, USB_IN and ANALOG_IN
boards. One of them is dedicated to the optional SYNC_IO board while the last one is default loaded with a CONTROL board, but
can be upgraded to a NETWORK board for Ethernet streaming capability. Note that optional boards MUST be installed by a
ualified technician. Failure to do so will void any warranty.
1.3.1 Digital inputs and CH Link: DIGITAL_IN board
Each DIGITAL_IN board provides standard digital inputs in XLR (AES-EBU), Coaxial RCA (S/PDIF) and Optical TOSLINK (S/PDIF)
formats as well as in the CH Link high-definition proprietary format. CH Link uses a dedicated connector to carry high resolution
audio and control data over a single link between CH units. It supports both PCM (up to 768kHz, 32bits) and DSD. To comply with
high definition digital content protection, DSD signals are cyphered when transported over CH Link from the D1 to the C1. On its
standard digital input connectors, C1 can lock to incoming S/PDIF modulated 16 or 24 bits PCM audio, at sample rates of 44.1, 48,
88.2, 96, 176.4 or 192 kHz, +/- 80 PPM.
1.3.2 USB Audio inputs: USB_IN board option
The USB_IN board provides asynchronous UBS audio input. Asynchronous mode means that the C1 is the clock master, and the
computer is the clock slave. Therefore no jitter is imported from the computer world. Moreover, all noisy digital devices on this
board (such as the DSP) are powered by the USB port (i.e. by the computer), and are galvanic isolated from the rest of the C1. The
USB input can be configured (in C1's menu) as audio class 1.0 (no driver re uired, Fs limited to 96kHz) or as audio class 2.0 (a
provided driver is needed for Microsoft Windows XP/Vista/7 systems, Fs up to 192kHz are supported).
1.3.3 Analog inputs: ANALOG_IN board option
The ANALOG_IN board features stereo analog input on two connector pairs: a single-ended RCA pair and a balanced XLR pair. The
analog stage design is fully discrete. One can find high-grade A/D conversion chip on this board, using the same high-precision
low-jitter clock signals as the two monaural DAC boards. The analog data are sampled at the rate of 5.6448 MHz (DSD2x) before
entering one 32 bit floating point DSP per channel. This option turns the C1 into an analog preamp.
1.3.4 External clock synchronization: SYNC_IO board option
The SYNC_IO board provides advanced clock synchronization options for C1 when used with an external clock generator or
matching CH source (such as the D1). It includes a clock input on BNC connector with selectable 75 Ohm or high input impedance.
Supported input fre uencies on this connector are all standard audio Wordclocks (44.1, 48, 88.2, 96, 176.4 and 196 kHz), audio
Masterclocks (22.5792 and 24.576 MHz), DSD bitclock (2.8224 MHz) and atomic-clock multiples (100 kHz and 10 MHz). When
fed with an audio Wordclock, the C1's internal clock will lock its VCXO internal clock in fre uency and in phase (phase accuracy of
12 C1 User Manual Rev 1.9

+/- 2.5 us), tracking below 0.1 Hz with 0.1 PPM corrections for optimal jitter rejection.
Two 75 Ohm Wordclock outputs completes the input/output capabilities of the SYNC_IO board.
When C1 is matched with a D1, both e uipped with a SYNC_IO board, the optimal configuration is to set the C1 as the clock master
(C1 clock source: INTERNAL), and D1 as the clock slave (D1 clock source: SYNCHRO BNC 75). In that case, connect one of C1's BNC
clock out to D1's clock in configured as a 75 Ohm input with a 75 Ohm BNC-terminated cable.
1.3.5 Ethernet streaming: NETWORK board option
The CONTROL board can be replaced by a NETWORK board, providing all the features of the CONTROL board, plus Ethernet based
audio streaming. Once a musical server is installed and configured properly, simply connect the C1's Ethernet plug to you local
network to use it as an audio renderer. High resolution audio format are supported, and the complete system is enslaved to the
C1's internal clock for jitter-free playback.
1.4 Power supply
The power supply of the C1 is a linear supply with multiple independent local regulations. It is based on an oversized magnetically
shielded toroidal mains transformer and includes a mains filter. A secondary (also toroidal) transformer is used as Standby
transformer to ensure green Standby mode, meeting the latest energy saving regulations. Both transformers have static shields
between primaries and secondaries. They are mounted on a separate steel plate which is isolated from the main base aluminium
plate by silent blocks.
Discrete (power-transistor and op-amp based) ultra low noise regulators are used throughout the power supply and special care has
been paid to the Masterclock power supply. The Masterclock benefits from its own dedicated supply, completely decoupled from the
noisy digital and motor sections. This ensures an ultra-low jitter clock source for the whole system.
Input AC voltage to the power supply can be set to 100V, 115V or 230V AC depending on your local mains voltage.
1.4.1 Optional external power supply
The C1 is e uipped with an external power supply input. This input is dedicated to the CH X1 external power supply. When the
external power supply is connected, the internal power supply of the C1 is turned-off (only the Standby transformer remains
active). Turning the internal power supply off ensures that no power supply induced noise or radiations are generated inside the C1
unit, thus permitting optimal operating conditions for the circuits.
Rev 1.9 C1 User Manual 13

2 Before Use
Please read the following carefully.
2.1 Package content
Make sure that the package content is complete. If not, please contact your authorized dealer. Your package should contain:
•C1 D/A controller
•Power cord
•Accessory box
•User Manual (this manual, located in the accessory box)
•C1 D/A controller Service Booklet with warranty card (located in the accessory box)
•Remote control (located the in the accessory box)
•Adjustment screwdriver (located in the accessory box)
•4x adjustment steel spikes (located in the accessory box)
•4x adjustment shafts steel stacking covers (located in the accessory box)
•4x adjustment shafts aluminum top covers (located in the accessory box)
Please store the packaging material for future transportation. Check your C1 D/A controller for apparent damages. In case of
damage, please contact your authorized dealer. If your C1D/A controller is still very cold from transport, please let it warm up to
room temperature in order to avoid condensation inside the unit.
2.2 Safety notice
Make sure to observe the following rules:
•Install your C1 D/A controller on a stable base
•Do not install your C1 D/A controller near water
•Always handle with care. The C1 D/A controller is uite heavy, so have someone help you when moving it around
•Do not expose the unit to any kind of li uid
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•Do not install in direct sun light or near any heat source such as radiators or other apparatus generating heat
•Do not install in a confined space and make sure sufficient air can flow around the unit
•Do not operate under high ambient temperature (>40°C) or with extremely high humidity such as in humid cellars
•Only use options and accessories specified or recommended by the manufacturer
•Do not open the unit nor try to service it by yourself. Do not try to install any option board by yourself. Always refer to a
ualified technician for service, maintenance or upgrades. Failure to do so will void the unit's warranty
2.3 User Manual
Please read this manual carefully before making connections or operating your C1 D/A controller. After reading, store the manual
in an accessible place for future reference. If, after reading this manual, you feel unsure about how to make connections or how to
operate the unit, please contact your authorized dealer.
2.4 Mains supply
Make sure to use 3 terminals (phase, neutral and earth) power cords with ground conductor. Make sure that the mains voltage
selection of the unit matches your mains voltage.
Make sure your C1 D/A controller is disconnected from AC wall power in the following cases:
•When making connections (it is also recommended to disconnect the rest of the system from AC wall power)
•When cleaning
•During thunder storms
•When unused for a long period
2.5 Transport and packaging
The C1 D/A controller must always be stored in its original packaging for transportation. Doing so will ensure optimal level of
protection of your unit. Therefore, keep all the packaging material in a dry and clean place for future use.
In addition, the transformer base plate must be secured for transportation to avoid excessive constraints on the silent blocks
isolating the chassis from transformer vibrations. This is done by the insertion of a security screw on the bottom of the unit. Do not
forget to install this screw for transportation and to remove it at installation of the unit in its new location.
Finally we recommend to remove the adjustment spikes and to put them into the accessory box for transportation. Indeed,
Rev 1.9 C1 User Manual 15

vibrations during transport may cause the adjustment spikes to move from their fully retracted position. There is risk of scratching
the installation base if the spikes are not fully retracted when installing the unit.
2.6 Cleaning
Use a soft, dry towel or cloth for cleaning. Never use any solvent or li uids as they may damage the surface treatment or
penetrate inside the unit.
2.7 Maintenance and ser ice
The C1 D/A controller contains no user serviceable parts. Do not try to open, modify or repair your C1 by yourself. This will void
any warranty. Your C1 D/A controller must be checked by a ualified technician in any of the following cases:
•The unit is not functioning properly
•The mains cable or the power cord receptacle is damaged
•The unit has been dropped to the floor or presents external damage
•The C1 D/A controller has been exposed to li uids (such as rain) or unknown substances
16 C1 User Manual Rev 1.9

3 Installation
3.1 Unpacking
Unpack the C1 D/A controller and store the packaging for future transportation. Be careful when lifting the C1 as the unit is heavy
(over 20kg). Get someone to help you if necessary. When unpacking and installing the C1, take care not to damage the high
uality surface treatments.
3.1.1 Remo ing the security screw
The transformer base plate must be secured during transportation to avoid damage to the isolating silent blocks. The security screw
is located at the bottom of the unit. To remove the security screw, tilt the unit on its side and unscrew. Do not tilt the unit on the
front or back panels as this may damage the user control knob or the connectors.
Security screw location
(1) Security screw. Must be mounted for transport and removed at installation
3.2 Positioning
Position the C1 unit on a stable base. Make sure cooling air is able to freely flow around the unit.
3.2.1 Unit position adjustment
The C1 D/A controller is e uipped with height adjustable feet. More precisely, each feet has an internal height adjustable spike
which can be accessed with the provided adjustment screwdriver through the adjustment shafts. When delivered from factory, the
adjustment spikes are not mounted in the feet but are located in the accessory box. Remove the adjustment spikes from the
accessory box and put one into each adjustment shaft. Place the provided screwdriver into the adjustment shafts and turn clockwise
to secure the spikes and make the re uired adjustments.
Rev 1.9 C1 User Manual 17
(1)

When the spikes are fully retracted, the C1 sits on elastomer rings to protect the base. If the base on which the C1 is located is
fragile or should not be scratched, please make sure to use the optional CH support discs to protect the base.
Adjustment shafts, feet and spikes
(1) Adjustment shafts. Insert adjustment spikes and use screwdriver to secure and adjust individual feet spikes
(2) Feet
(3) Adjustment spike heads (when inserted into adjustment shafts)
(4) Adjustment spike
3.2.2 Adjustment shaft co ers
Once the position of the unit is adjusted, place the appropriate shaft covers on the four adjustment shafts. There are two types of
shaft covers delivered with your C1 unit. One type of shaft cover (stacking cover, made of steel) is used when different CH units
are stacked. This type of cover includes a receptacle to receive the corresponding spike of the unit placed just above. By doing so,
mechanical vibrations are optimally transmitted to ground and minimized inside CH units. The second type of shaft cover (top
cover, made of aluminum) can be used when units are not stacked or for the top unit when stacked. It covers the shaft and
provides a smooth finish to the top of the unit. Shaft covers are located in the accessories box delivered with your C1 unit.
Never stack any component other than CH's on your C1. Never use the aluminum shaft covers (top covers) when another CH
component is to be stacked on top of your C1.
Shaft co ers (left: stacking co er, right: top co er)
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3.3 Connections
This section provides information about how to connect your C1 D/A controller to your system. As the C1 is a modular design with
different optional boards, the description applies to the example configuration presented below. If your options do not match the
example or you don't feel secure with the connections to be applied to your configuration, please contact your authorized dealer
for assistance.
The example configuration is a full featured controller with many inputs (standard digital input AES-EBU, Coaxial and Optical, CH-
Link, USB and balanced and single-ended analog in) and clock synchronization option (SYNC_IO board). This is one of the most
complete configurations of C1. If your configuration does not include some of the presented options, just discard the corresponding
connections.
Rear panel connections
(1) 75 Ohm RCA single-ended analog output for right channel
(2) 50 Ohm BNC single-ended analog output for right channel
(3) 75 Ohm RCA single-ended analog output for left channel
(4) 50 Ohm BNC single-ended analog output for left channel
(5) BNC clock input. Provides 75Ohm or Hi-Z input. [optional SNYC_IO board]
(6) Ethernet port for command interface [CONTROL board] or for audio streaming and commands [optional NETWORK board]
(7) TOSLINK (S/PDIF) digital input [DIGITAL_IN #1 board]
(8) AES-EBU digital input [DIGITAL_IN #1 board]
(9) USB audio [optional USB_IN board]
(10) RCA single-ended analog input for left channel [optional ANALOG_IN board]
(11) XLR balanced analog input for left channel [optional ANALOG_IN board]
(12) Earth connector. Internally connected to digital ground
(13) External power supply connector for X1 power supply option
(14) Power on/off switch
(15) XLR balanced analog output for right channel
(16) XLR balanced analog output for left channel
(17) BNC 75 Ohm clock output 2. [optional SYNC_IO board]
(18) BNC 75 Ohm clock output 1. [optional SYNC_IO board]
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(19) USB port for software upgrades. [CONTROL board or optional NETWORK board]
(20) CH Link digital input [DIGITAL_IN #1 board]
(21) Coaxial (S/PDIF) digital input [DIGITAL_IN #1 board]
(22) RCA single-ended analog input for right channel [optional ANALOG_IN board]
(23) XLR balanced analog input for right channel. [optional ANALOG_IN board]
(24) Analog ground connector 2
(25) Analog ground connector 1.Can be connected to digital ground (Earth) using provided jumper
(26) Power fuse and voltage selection
(27) Power cord receptacle
The CONTROL board is mandatory in any C1 configuration and is always factory installed. It can be upgraded by an optional
NETWORK board that replaces it, covering all functions of the CONTOL board plus audio streaming capability. Depending on
optional boards and their arrangement in the C1's expansion slots, connector arrangement may differ on your unit. Each C1 unit
provides 4 expansion slots supporting any combination of the following optional boards (note that one slot is dedicated to the
SYNC_IO board):
•DIGITAL_IN boards (one is already installed in the default C1 configuration) provides 4 digital inputs (coaxial S/PDIF,
optical TOSLINK, AES-EBU and CH-Link)
•USB_IN boards provides an asynchronous USB audio input
•ANALOG_IN boards provides 2 pairs (L+R) or analog inputs (balanced XLR and single-ended RCA)
•SYNC_IO board for external clock synchronization
Note that only one SYNC_IO board is allowed. Optional input boards can be placed in any slot. Installation of optional boards must
be done by a ualified technician only. Do not attempt to install any optional board by yourself as this would void the unit's
warranty.
3.3.1 CONTROL board
The CONTROL board is factory installed into the C1. It provides a USB port for software updates and an Ethernet port for controlling
the unit over a network. Following drawing shows the layout of the back panel of the CONTROL board:
CONTROL board back panel layout
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