The HD DAC X share the same New Digital board made in Switzerland by Nagra 72 Bit / 11.2 MHz. 8 core
Digital board, that also includ all the digital connections so it can be replace for future innovations.
Both feature AES-EBU, S / P-DIF inputs are studied by Nagra, the new Nagra Link single-mode ST-1 optical inputs to receive in the near future, new sources of very high resolution Nagra.
Both have the USB input, around a 8-core X-Mos chip.
Ultra high precision and ultra low jitter clocks are used in this new Nagra DAC.
A high power FPGA performs all calculations; all audio sources are in DSD256 format (11.2 MHz sample rate).
The digital part alone uses 16 ultra low noise power supplies.
Some digital power supplies have noise levels 30 times lower than the HD-DAC, itself already using very low noise circuits. The order of magnitude of the noise of these new power supplies is 0.4 to 0.8 uV RMS (from 10 Hz to 100 kHz).
The 8-layer, high-précision PCB is also of very high précision.
The analog part is very original. The principles used within the Nagra HD-DAC have been taken over and improved.
Here some of the différence that the HDDAC X have :
Higher voltage, the power supply is very sophisticated, using ultra-fast silicon carbide rectifier diodes, ultra low-noise voltage regulators, and a virtual battery system made up of many supercaps. (3 times more than the HD-Preamp).
The new HD-DAC-X and its power supply use no less than 37 regulated power supplies. Also the Chassis is bigger so we can use larger capacitors.
The 8-layer, high-précision PCB is also of very high précision.
The analog part is very original. The principles used within the Nagra HD-DAC have been taken over and improved.
The impedance of the signals is strongly lowered by a symmetrical current amplifier, of very high performances, without voltage gain, without feedback.
The rise time is of the order of 1800 V / uS on the 28 H inductive load of the gain-up transformers.
The voltage gain is only achieved by new high-end audio transformers, studied by Nagra engineers. The other role of these transformers is to unbalance the audio signal to attack a single-ended tube mount. These transformers are built exclusively in Nagra workshops, by the best specialists.
The performance of these transformers is an important part of the audio quality of this new Nagra HD DAC X. Performance has been improved over transformers used in the old HD-DAC.
An impedance reduction is performed by a stage consisting of two military tubes NOS JAN5963, cathodyne output. The tensions of the heating filaments of the tubes are individually regulated by tube, by very low noise systems.
No feedback is used around this stage, as on the current amplifier preceding the audio transformers.
Numerous special components, some of which are custom-built on Nagra's specifications, are used within this new DAC.
Advanced mechanical isolation, the audio engineers created a super vibration free stand to lower the microphonic resonances to a new level.
Rene Laflamme, Nagra audio
