C1 Mono – Dual Monaural Digital to Analog Controller (legacy)

Digital signals carry stereo information in a single data stream. That means that we cannot follow our normal approach to scalable system architecture, using independent C1 DAC Controllers for left and right channels, as we have to have a single input connection. Instead, to deliver improved performance, we retain the C1 input architecture but then split the digital information into left and right channels for routing to dedicated external DACs, with a single chassis for each channel. This allows us to retain the exceptional functional flexibility of the C1 and the scalability of the system, while delivering a genuinely significant upgrade in performance.

“Neutral, exciting, fast, tons of detail, yet musical in a way that is honest to the source, not gussied up with bloom and decay trails, it is not like the audio we grew up with. This kind of sound did not exist until now. As far as I’m concerned, CH Precision is at the forefront of digital technology. They are the leader of the pack.”


Product Description

Feeding the left and right channels to independent DACs allows us to provide dedicated, fully regulated power supplies for the digital processing and decoding functions electrically isolating these critical processes from the control functionality and the optional analog inputs. By placing the DACs in completely separate chassis units, we achieve zero crosstalk between the two channels and prevent high-frequency contamination of the critical analog power supplies. The analog output from each DAC chassis retains the discrete, fully-complementary topology of the C1, but now with a dedicated power supply for each channel, further reducing noise and increasing stability. The improved performance of the output stage adds dynamic range and authority to the C1 Mono’s musical performance, to match the added resolution of its digital stages. The end result is the most musically natural and satisfying digital replay we have ever achieved.

Read more (PDF)

Standard Inputs

  • Factory fitted with CH-Link HD, AES/EBU, S/PDIF and TosLink digital inputs
  • The CH-Link HD interface allows for synchronized transfer of high definition audio content (up to 32bit/768kHz) and DSD, offering the ideal interconnection to the D1 CD/SACD Transport or other CH-Link HD equipped units
  • Standard digital inputs accept PCM to 24bit/192kHz, DSD 1bit/2.822MHz (DSD64)

Optional Digital Inputs

  • The C1 can accept up to three digital input boards to allow multiple digital sources to be connected
  • Ethernet audio streaming input board, UPnP/DLNA compatible, allows connection to audio servers (NAS drives), streaming services and internet radio
  • PCM to 24bit/192kHz (384kHz for uncompressed formats)
  • DSD 1bit/2.8224MHz (DSD64), 5.6448MHz (DSD128) or 11.2896 MHz (DSD256)
  • Native DSD and DoP
  • WAV, AIFF, FLAC, ALAC, AAC and MP3 formats supported in PCM
  • DSF and DFF formats supported in DSD
  • Asynchronous USB audio input board – PCM to 24bit/384kHz, DSD 1bit/5.6448MHz (DSD128, DoP encoded)

Digital to Analog Conversion

  • Four PCM1704 R-2R converters per channel
  • Fully complementary, dual mono symmetrical circuit topology
  • Discrete dedicated regulated linear power supplies for low noise and maximum channel separation


  • Independent 2.4GFLOPS DSP engines for each channel
  • Proprietary CH-PEtER synchronous data over-sampling processing
  • DSD to 705.6kHz PCM conversion
  • Resolution enhancement of audio material recorded at less than 24bits
  • Digital to Analog converters data scrambling
  • Linearization of the R-2R converters through on-board calibration process

Timing & Clocking

  • Ultra low jitter digitally controlled VCXO oscillators with dedicated power supplies
  • Optional master/slave Clock-Sync board allows synchronization with external clocks when used with the D1 CD/SACD transport, I1 Universal Integrated amplifier or computer-based audio source
  • Clock-Sync board also allows use of the T1 10MHz Time Reference clock

Volume Control

  • By-passable 0.5dB step hybrid volume control, coarse steps using relays and a resistor ladder and fine steps in the digital domain, to maximise system resolution

Analog Input Board

  • Discrete, fully differential analog input circuit
  • Balanced XLR and single-ended RCA inputs
  • 6V RMS maximum input level
  • Input offset and balance user selectable

Analog-to-Digital conversion

  • DSD 1bit/5.6448MHz (DSD128) direct conversion

Analog Output Stage

  • Pure class A, fully symmetrical circuit
  • Fully discrete, ultra low noise, high slew rate design
  • Zero global feedback
  • One pair each – balanced XLR, single-ended RCA and BNC outputs
  • DC coupled
  • 5.4V RMS maximum output (balanced XLR), 2.7V RMS maximum output (single-ended RCA/BNC)
  • Switchable absolute phase
  • Channel balance in 0.5dB steps


  • 480 x 272 pixel, 24bit RGB AMOLED
  • 15 standard, user-selectable text colors
  • User definable RGB option for text color

Remote Control Options

  • Infrared Remote Control handset for basic functions

Optional Hardware

  • Digital Input Board – CH-Link HD, AES/EBU, S/PDIF and TosLink
  • Network Player Input Board
  • Asynchronous USB Input Board
  • Clock-Sync Board
  • Analog Input Board – one pair balanced XLR, one pair single-ended RCA
  • Fully compatible with X1 External Power Supply
  • Compatible with T1 10MHz Time Reference external clock (with Clock-Sync board)

Technical Specifications

Conversion type
Linearized R-2R, 4x PCM1704 per channel
24 bit / 705.6kHz & 768kHz

DSP processing
CH-PEtER upsampler, synchronous, DSD to PCM
conversion and resolution enhancer

Full scale analog outputs level
5.4V RMS balanced
2.7V RMS single-ended

Signal to Noise Ratio
> 120dB

Total Harmonic Distortion + Noise
< 0.001%, full scale, 22kHz BW

440 x 440 x 133mm (W x D x H), 20kg per unit

C1 Mono Specific Downloads

Some of our awards