Audio-GD - D27.28 Balanced Dual ES9028 PRO FPGA 3x Accusilicon AS318B DAC / Pre / Headphone Amplifier (DSD, DxD, Amanero USB)
Balanced Headphone & pre- amplifier with integrated digital analogue converter based on flagship from Sabre, the Dual ES9028Pro. All parts and components are selected based on excellent sonic and measurements performance. Components are e.g. from DALE resistors (USA), WIMA capacitors (Germany) and NOVER parts (UK) . The used components but also the technical design (e.g. discrete analogue section) of this system were being selected after many years of experience and practices and are considered to perform and provide sublime sonic results. Supporting today's high resolutions and up to date interfaces like USB and I2S.
Latest update: Volume boards are equipped with Vishay KOA resistors (dual parallel) to achieve very low tolerance (0.05%)
Dual ES9028Pro design, one per channel in mono mode, this improves the channel crossover and sound stage is larger and extremely precise.
The ES9028 version could be ordered at speical request; the ES9038 PRO is highlly recommended!
2019 version of D27
3x Femto Accusilicon 318B oscillators clocks included
DC-Servo no-compromise OPA opamp with transistor upgrade included
- Discrete balanced DAC & headphone- & pre-amplifier
- Three Femto Accusilicon 318B oscillators clocks
- DSD & DXD support from USB and I2S
- Dual Sabre ES9028Pro 32bit / 768K
- Asynchronous 32bit / 384K transfer USB-32 Chip
- Shortest current driven signal path with discrete and DC coupled ACSS output stages
- R-core transformer
- DALE resistors (USA), WIMA caps (Germany) and NOVER components (UK)
- 6-group PSU's to purify the power supply
- Four-channel digital controlled relay-based volume control to avoid channel imbalance and will improve sound quality
- 80 steps volume control in both high gain mode and low gain mode. smooth volume level control
- Static storage control software to avoid degrade sound quality, the MCU will be disabled when inactive
- Amanero combo384 with isolation
FULLY MENU CONTROLLED - NO JUMPERS
- 1. Coaxial RCA SPDIF
- 2. Toslink / Optical
- 3. HDMI I2S LVDS
- 4. USB Amanero
- 5, Analog XLR input
- 6, Analog RCA input
Line outputs can be set to variable or fixed
- ACSS balanced
- XLR balanced
- RCA single ended
- Headphone (4-pin) XLR balanced
- Headphone 6,3mm jack single ended
- Separate the data for left en right channel for each ES9028 Pro mono for best performance
- Re-clock process and FIFO design for all inputs; output data is synchronized with clock signal to reject jitter.
- Built in high performance SPDIF interface to avoid usage of the poor performing SPDIF interface inside the ES9028 Pro.
HIGH PRECISION VOLUME CONTROL
Volume control consist of relay-controlled attenuators. Fully-independent, fully-balanced stereo volume controls. The volume controls feature consist of high-precision 0.05% tolerance film resistors and golden contact relays. Buffered inputs and outputs.There 4 channels volume boards are built in the unit to achieve ultimate balanced volume control. They are controlled by a digital signal controlling the high quality relays switching the precision resistors in analog area.
|Audio-GD lineair volume characteristic
||Volume steps in comparison to standard volume control
Quality of volume control is very important in balanced applications . It have to effectuate the four channels to work as synchronous as possible to keep the balanced signal in perfect shape. In traditional volume controls the balanced output will introduce distortion which will negatively influence sound quality and performance and might even get worse than a single ended setup and waste the advantages of balanced designed solution.
ANALOGUE OUTPUT STAGES
The final step the of the signal flow are the analog output stages, they can have a massive effect the total sound quality.
The output stages are directly placed behind the ES9028 pro dac chips and they are built with discrete transistors through-hole components becuase this offers the best results we discovered after many years of experience.
The high speed ACSS (propitiatory Audio-GD current driven signal processing system) are non feedback designed and work in current signal mode, hence the dual ES9028 pro output is in current mode amplified by the ACSS amp. No shortcuts are taken; a complete current driven solution.
The output buffers are the pure class A , built with 4 pcs 150W (in total 600W ) per channels; to drive even the most difficult headphone without any problem. The class A output stages will make sure you will get the most pure and real sound reproduction.