The C1 Mono retains the C1 input architecture but then splits the digital information into left and right channels for routing to dedicated external DACs, with a single chassis for each channel. This allows CH to retain the exceptional functional flexibility of the C1 and the scalability of the system, while delivering a genuinely significant upgrade in performance.
C1 Mono Dual Monaural D/A Controller
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.
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 analogue 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 analogue power supplies. The analogue 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.
Owners of existing C1 units wishing to upgrade them to dual-monaural, three chassis status can do so by having their C1 modified and adding the separate mono DACs – without any cost penalty. The price of the complete upgrade is the same as the difference in cost between the C1 and C1 Mono. The C1 Mono is also compatible with X1 external power supplies, so that owners who have matched an X1 to their C1 can add a second output board to their power supply and use it to drive both DACs. Or of course, you can simply add dedicated X1s to both the DACs and the C1 controller, creating a six-box true dual-monaural system. For ultimate performance, add a T1 10MHz Time Reference with its GPS facility, while a D1/X1 and CH-Link HD will provide optimum replay of material from CD/SACD discs.
Every CH Precision product conforms to our model of modular construction and scalable upgradability – but none take that concept as far, or offer the potential performance benefits enjoyed by the C1 Mono. It is our digital masterpiece.
Up to three input boards allows the unit to include many input types. One digital input HD board is provided in base configuration, while two slots are kept free and can be fitted from factory or after product installation with the following board types:
- digital input HD board (1x CH Link HD, 1x AES/EBU, 1x S/PDIF and 1x Toslink)
- analogue input board (1x XLR balanced and 1x RCA single-ended)
- USB input (1x USB B-type)
The CH-Link HD interface allows for synchronised transfer of High Definition audio content and control over a single connection and is the optimal link between the C1 mono and the matching D1 SACD/CD drive. Audio data on CH-Link HD is cyphered when protected content is transmitted.
The ethernet audio input board option replaces the ethernet control board, turning the C1 mono into a UPnP, Tidal, Qobuz and Web radio compatible network player. It should be noted that this input can be added even if the three available input slots are fitted.
For each channel a fully programmable 2.4GFLOPS DSP engine is used for the following processes:
- proprietary CH-PEtER processing for data upsampling at 705.6kHz/768kHz
- DSD to PCM direct conversion at 705.6kHz
- resolution enhancement for data streams of less than 24 bits resolution
- D/A converters data scrambling
This DSP engine also linearises each of the four R-2R converters – its absolute output level as well as DC offset is taken into account – thanks to a calibration process which is done at factory but can also be performed by the user afterwards to maintain optimal operation over time.
Timing & clocking
Extreme care has been given to the timing of the audio conversion. The clocking section of the C1 mono is based on two ultra low jitter digitally controlled VCXOs to support synchronously every available audio sampling rates.
When equipped with the optional synchronisation board, the C1 mono can be used with external clock generators like the CH Precision T1, or it can transmit the D1 SACD/CD drive a synchronisation clock in order to slave it.
The digital to analogue converter boards are full dual mono with one board per channel. A dedicated set of regulated power supplies has been built for each channel in order to keep the channel separation at its maximum. Each channel is using four R-2R converter in a balanced design to create directly from the D/A conversion process an analogue balanced signal.
An integrated hybrid volume control is embedded into the C1 mono, which can be turned off in case an external analogue preamplifier is used. It has been done with a mix of analogue and digital steps to ensure the best possible resolution at all listening levels. Coarse steps are done with relay-driven resistor-based dividers, while the fine steps are done into the DSP engine in floating point.
All analogue stages of the audio signal inside the C1 mono are built only with discrete components, no operational amplifier have been used into these sections. This deliberate choice warranties the shortest path for the audio signal and allows the use of custom-designed building blocks. All analogue stages have the following features:
- no use of global negative feedback
- operating mode in pure class A
- fully symmetrical design
No capacitors have been used in the signal path to ensure the maximum transparency.
|CH Link HD||
High Definition Link
PCM 16 to 32 bit / up to 768kHz
|AES/EBU||XLR connector, up to 5Vpp, 110Ω
PCM 16 to 24 bit / up to 192kHz
|S/PDIF||RCA connector, up to 1Vpp, 75Ω
PCM 16 to 24 bit / up to 192kHz
PCM 16 to 24 bit / up to 192kHz
PCM 16 to 32 bit (fixed point) / up to 384kHz
PCM 16 to 32 bit (fixed point) / up to 192kHz (384kHz for uncompressed formats)
WAV, AIFF, FLAC, ALAC, AAC, MP3 format supported in PCM
|Inputs type||Balanced, 6V RMS maximum input level
Single-Ended, 6V RMS maximum input level
|Input stage||Discrete fully differential input stage|
|A/D conversion||DSD 1 bit / 5.6448MHz (DSD128) direct conversion|
|Conversion type||Linearised R-2R, 4x PCM1704 per channel, 24 bit / 705.6kHz & 768kHz|
|DSP processing||CH-PEtER upsampler, synchronous, DSD to PCM conversion
and resolution enhancer
|Outputs type||Balanced (XLR), one pair
Single-Ended (RCA & BNC), one pair each
|Output stage||Discrete I/V stage with ultra-high bandwidth
Active discrete filtering stage
High-current discrete output stageAll analog stages have a zero global negative feedback
|Output level||5.4V RMS in balanced mode
2.7V RMS in single-ended mode
|Signal to Noise Ratio||Better than 120dB|
|Total Harmonic Distortion + Noise||Less than 0.001%|
BNC, 0.5Vpp to 5Vpp, 75Ω or Hi-Z
44.1kHz, 48kHz, 88.2kHz, 96kHz, 176.4kHz, 192kHz, 352.8kHz, 384kHz
2x BNC, 2Vpp, 75Ω
input sampling frequency or clock loopback if externally synchronised
|Display||480×272 pixels, 24bits colour, AMOLED|
|Mains operation||Selectable 100V, 115, 230V AC, 47-63Hz|
|Fuses value and location||Standby fuse (black holder): 250mA T (230V AC), 500mA T (100V AC, 115V AC)
Main fuse (white holder): 1.6A T (230V AC), 3.15A T (100V AC, 115V AC)
|Power supply consumption||<1W (standby), 60W average in operation|
|Dimensions/Weight||440 x 440 x 133mm (W x D x H), 24kg|
|Remote control||IR Remote control provided, RC5 codes
Ethernet based system control via the Android CH Control App