Apollo is a single-unit multi level Delta-Sigma Digital-to-Analog Converter (DAC) utilizing the latest 3d generation Asahi Kasei Microdevices AK4493EQ IC’s in a «dual mono» configuration.
Apollo has been designed as a standalone pure DAC foregoing any and all superflous functionality in the pursuit of industry-leading sound quality.
Apollo should be mated with a High End digital file transport, net player or renderer for optimum usability and comprehensive digital source integrity. The new Apollo DAC represents the pinnacle in modern digital audio, achieving unparalleled dynamic range of over 150 dB and the highest full frequency range definition combined with fabulous immediacy and musicality.
MAIN FEATURES:
Tchernov Audio proprietary FDAP (Functional Digital & Analog Platform) defines the entire design philosophy.
INIMOL (Intrinsic Noise Immunity Module Layout) topology for signal path tracing optimization and reciprocal interferences minimisation. Development of Tchernov Audio.
Built-in-house dual frequency masterclock oscillator with super high short-term stability. Development of Tchernov Audio.
PCGS (Phase Correlated General Synchronization) system provides end-to-end synchronization of the display and control processes with the DAC masterclock. Development of Tchernov Audio.
Aerospace grade multi-layer PCBs are made of reinforced vibration absorbing foiled material (2,5 mm) with enhanced 70 μm copper foil tracks, covered with antistatic mask. All the vias and pads are immersion gold plated.
High energy power supply featuring 3 independent custom built transformers with minimal core induction, small value and peak factor of the idle current, aimed at reducing loss and interference.
Industrial grade matrix LED display and low noise control circuits with PCGS and special PCB layout avoiding detrimental effects on sound performance.
6 Selectable digital filters with different slope and group delay characteristics.
Digital domain phase inversion.
Direct DSD-to-Analog conversion without any intermediate data processing stages. Clickless DSD/DSD and DSD/PCM data switching software and hardware.
3 independent and galvanic isolated USB Audio 2.0 inputs.
Switchable wordclock/masterclock output.
Immensely strong and well isolated precision milled seamless aluminium chassis.
FORMATS & INTERFACES
Apollo DAC receives digital audio streams in two main formats - USB Audio 2.0 and AES. AES format has two different physical interfaces: AES/EBU x 1 (XLR) and SPDIF x 2 (RCA).
The AES inputs provide PCM data reception up to 24 bits at a sampling rate up to 192 kHz.
The USB inputs support PCM data (up to 32 bits at a sampling rate up to 384 kHz) as well as DSD 64, DSD 128 and DSD 256.
The digital interface modules provide galvanic isolation of all input signals from the DAC module and slave data synchronization with the Apollo DAC masterclock signal.
Switchable wordclock / masterclock output: x 1 (BNC).
Stereo analog outputs: XLR x 1; RCA x 1.
FDAP PLATFORM
There is a strong relationship between Delta-Sigma DAC distortion with its power and reference voltage values and their correlation. The multi-level Delta-Sigma conversion dynamic range (low level conversion linearity) strongly depends on the clocking signal quality (its short term stability and phase noise), referenced to the physical D/A conversion point.
With these concepts established, the proprietary Functional Digital & Analog Platform (FDAP) came into being. FDAP defines the entire Apollo design philosophy and includes the following key data processing and signal refinement attributes:
Extremely wide Spurious Free Dynamic Range - SFDR
High stability & low noise reference and power voltages with their estimated mutual correlation for each DAC IC
Precision D/A conversion timing
Clocking narrowband spectrum & low phase noise
Distortion spectrum with falling envelope
Low noise and negligible clocking interference induced to the analog circuits
High external noise immunity of digital and analog circuits
The unique schematics and PCB topology guarantee the high precision timing scale and provide the extreme Spurious Free Dynamic Range (SFDR). Such a solution results in an awesome scale definition, tonal balance and timbre accuracy.
SINGLE CHASSIS PRINCIPLE
Apollo audio DAC is a single chassis unit, which is a deliberate point of design. Two- or more- chassis designs introduce as many issues as they claim to solve. A separate power supply is primarily used to reduce the transformer’s magnetic and vibration influence on
the signal circuits. Such a solution makes sense only when using ordinary power transformers with maximum savings in mind. The unique properties of our highly tailored power transformers combined with their effective shielding and vibration protection allowed us to completely abandon the meaningless and prodigiously priced two- and morechassis architecture.
We consider the separate clock unit design even a more detrimental step. The accuracy of the D/A conversion depends not only on the converter specs in the amplitude domain, but on the short-term time scale accuracy as well. It is determined by phase noise (jitter) of the clocking signal. The use of sophisticated rubidium generators with the highest long-term stability is largely irrelevant for DAC devices and is aimed primarily at amusing the wouldbe owner and justifying the steep retail price of the product.
Moving the clock oscillator away from the physical D/A conversion point is just as harmful as the above. The external interference induced on the transmission line increases clock signal noise and jitter thus significantly degrading the conversion accuracy.
The ultra low noise dual frequency masterclock oscillator located close to the DAC IC’s eliminates these issues entirely. The overall jitter level of the Apollo DAC masterclock oscillator at the physical D/A conversion point is lower than 50-60 femtoseconds.
INIMOL TOPOLOGY
INIMOL (Intrinsic Noise Immunity Module Layout) topology was engineered for signal path tracing optimization and reciprocal interferences minimization. The DAC module, power supply, control and display circuits are enclosed in a rigid milled aluminum alloy chassis with high EMI suppression and excellent vibration absorption.
The mutual arrangement of all modules, nodes and their wiring is designed and executed in such a way as to minimize the length of external connections, aimed at reducing mutual interference and providing non-intersecting paths of digital, analog and control signals.
DAC MODULE
The DAC module embeds the 3d generation multi-level Delta-Sigma Asahi Kasei Microdevices AK4493EQ IC’s in a «dual mono» mode. Each channel is based on a separate DAC IC with particular antialiasing filters and power supplies.
The DAC module digital functional nodes are powered by individual integral regulators, with additional LC filters for each IC.
Each DAC IC is powered by 5 independent ultra low noise discrete regulators with very high long term and temperature stability. The ratio of the DAC IC’s reference voltages and power supply voltages is selected by the criteria of minimizing the THD and ensuring the uniformly falling distortion spectrum envelope.
The analogue circuits are powered by separate low noise discrete voltage regulators with high ripple suppression, low output impedance and aperiodic transient response. The DAC IC’s analog output signals are precisely filtered by individual antialiasing Bessel
4th order filters and processed by 2-stage filters-subtractors to achieve maximum in-phase noise reduction.
MASTERCLOCK OSCILLATOR MODULE
Tchernov Audio team has designed the proprietary dual frequency masterclock oscillator. It is a super high short-term stability quartz oscillator based on special crystal cut with a very high Q Factor. The entire circuits are powered from an ultra low noise discrete
regulator with high voltage constancy and excellent ripple suppression. The oscillator assembly is placed in a milled hermetically sealed shielding enclosure and filled with a vibration absorbing compound. The new masterclock oscillator is characterized by ultra low phase noise (jitter) and is entirely built in Russia.
POWER SUPPLY
Apollo DAC is powered by a classic linear PSU with three customized power transformers for independent DAC, interface, control and display circuits servicing. Each power transformer is specially designed and fabricated in-house with minimal core induction which results in extremely low external magnetic field, small value of an idle current and negligible vibration. The primary windings of the transformers are powered via individual EMI filters. All transformers are placed in a common magnetic steel shielding enclosure filled with a vibration absorbing compound.
The rectifiers are based on a 3-d generation true Shottky SIC diodes and are equipped with special suppressing circuits.
Apollo's power supply has a high energy hoard. The total value of the filter capacitors is over 110000 μF. A soft start circuit is applied to avoid an extra current when the capacitors start charging.
PRINTED CIRCUIT BOARDS
All Apollo modules utilize precision multi-layer printed circuit boards (PCB’s) made of reinforced vibration absorbing foiled material (2,5 mm) with uniform dielectric permittivity over the surface and enhanced 70 μm copper foil tracks. The PCBs are covered with an antistatic mask, all the vias and pads are immersion gold plated.
Such a solution enables to optimize the conductor’s topology with the view to minimize radiated interference and boosting the intrinsic noise immunity. All the conductors in the digital block, clock signals, data streams and synchronization are engineered to ensure the
minimal emission and reflections in the circuit. The DAC IC’s masterclock circuits are implemented as a closed waveguide matching structures in the inner PCB layers. A further increase of noise immunity is achieved by sectoral grounding polygons in a separate board
layer and optimal power line tracks. The PCB’s are made in Russia.
DISPLAY AND CONTROL
In Apollo we came out with the PCGS technology. It serves for the total end-to-end synchronization of all servo microcontrollers with the masterclock oscillator thus avoiding their attendant detrimental effect on sound quality.
Apollo’s industrial grade matrix LED display is synchronized with a masterclock and does not produce any sampling uncorrelated interference. The similar clocking is applied to the servo controllers in the interface module and the DAC module. Such a complex engineering contributes to the industry-leading level of the audio performance.
CASEWORK & CHASSIS
The Apollo DAC chassis has been designed from the outset to be an effective vibrationabsorbing and mechanically extremely robust assembly with excellent electromagnetic shielding properties. The chassis and cover are milled from an integral aluminum alloy billet implementing special reinforced inner structure and high shielding qualities. The ultrasonic flaw detection is applied after milling to avoid any internal defect. The supporting feet location points are determined by the computer simulation of the soundwave interference pattern in the chassis bottom at a variety of frequencies.
SPECIFICATIONS
Digital inputs
Balanced AES/EBU x 1:
IEC60958/AES3 compliant (XLR, 110Ω), 44.1 kHz to 192 kHz 16 to 24-bit 2-channel PCM
Coaxial SPDIF x 2:
IEC60958/AES3 compliant (RCA, 75Ω). 44.1 kHz to 192 kHz 16 to 24-bit 2-channel PCM
USB x 3:
USB Audio 2.0 High Speed
44.1 kHz to 384 kHz 16 to 32-bit 2-channel PCM
2.8224 MHz, 5.6448 MHz, 11.2896 MHz (1-bit 2-channel DSD)
Analogue outputs
2-channel balanced analog audio output (XLR)
2-channel single phase (unbalanced) analog audio output (RCA)
Frequency response (PCM)
Sampling frequency 44.1/48 kHz: 0 - 20000 Hz (-0.3 dB)
Sampling frequency 88.2/96 kHz: 0 - 27000 Hz / 0 - 29000 Hz (-1.5 dB)
Sampling frequency 176.4/192 kHz: 0 - 45000 Hz / 0 - 49000 Hz (-3 dB)
Sampling frequency 352.8/384 kHz: 0 - 52000 Hz / 0 - 54000 Hz (-3 dB)
Frequency response (DSD)
DSD 64: 0 - 20000 Hz (-0.3 dB)
DSD 128: 0 - 30000 Hz (-2 dB)
DSD 256 0 - 48000 Hz (-3 dB)
Analog Output Voltage
Full scale signal (FSS): 2.1 V (RMS)
Output Resistance
RCA 50±5 Ohm (0 Hz - 500 kHz)
XLR 50±5 Ohm (0 Hz - 500 kHz)
Harmonic Distortion
PCM (24 bit FSS) ≤ -112 dB
DSD (FSS) ≤ -112 dB
S/N ratio
Full scale signal (FSS): ≤ -119 dB
Dynamic range
-60 dBFS signal ≥ 147 dB
Master Clock
Totally switchable oscillators
Oscillator jitter (RMS type low frequency) ≤ 0.06 ps
Long term stability ≤ 10 ppm
Power Supply
AC (according to regional specs): (100/110/120/220/230/240) V (50/60/400) Hz
Power consumption ≤ 65 W
Mechanical
Net weight 18 kg (39.7 lbs)
Width 455 mm (17.92 in)
Height 148 mm (5.83 in)
Depth 400 mm (15.75 in)
