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
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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.
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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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