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Audio-GD - NFB 28 (Balanced Pre & Headphone Amp ES9028PRO Amanero USB DAC)
Balanced Headphone & pre- amplifier equipted with hyper-modern Sabre ES9028Pro dac chip. 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 sublim sonic results. Supporting todays 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%)
This version includes the low jitter TCXO clocks & Amanero USB options
Optional Femto Accusilicon AS318B oscillators clock
DC-Servo no-compromise OPA opamp with transistor upgrade included
Volume Boards are equipped with Vishay or KOA resistors, very low tolerance 0.05% .
- Discrete balanced DAC & headphone- & preamplifier
- DSD & DXD support from USB and I2S
- 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
- 1. USB input.
- 2. I2S Asynch. input (RJ45)
- 3. Toslink optical SPDIF
- 4. RCA coaxial SPDIF
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
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 chip 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; the 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 to drive difficult headphone without any problem. The class A output stages will make sure you will get the most pure and real sound reproduction.