Audio-GD R27HE

HIGHLIGHTS

Regenerative Power Supply built-in
USB fully integrated and Isolated with internal FPGA deriving clocks from Accusilicon’s (similar to DI20 architecture)
I2S HDMI isolated input
IN2 coaxial input accepts external 10MHz clock input ( 75 ohms )
Firmware upgradable design
True balanced design, discrete push-pull R2R DAC design
Improved clock timing of internal master clock regeneration.
Discrete analogue output stages
DC coupled design (No capacitors in signal path)
Non- feedback ACSS analogue output control

R-2R LADDER DAC

The R-2R DAC has become popular and was originally designed long time ago by MSB, and did not include the wonderful correction design of the modern MSB technology. In the High-End of the shelf (finished products) market, the R2R design is usually much more complex when outstanding performance is offered. Some manufacturers are using shift registers design to realize ladder compensation. A less complex, unfortunately also a less performing.
A far better design switches resistors in parallel mode; an ultra-fast FPGA chip controls and corrects the R2R ladder. The parallel design mode controls every bit respectively and therefore achieve unprecedented performance. (In parallel mode only 1 clock cycle is needed to output all data; serial design mode needs at minimum 8 up to 24 clock cycles) The parallel design is particularly complex, however when it is done properly it can correct every bit of the ladder. (Photo below shows a FPGA design with R2R ladder). With incredible speed and accuracy the R-28 will correct the unavoidable imperfections of the basic R2R ladder caused by tolerance of resistors; avoid glitches at ultra-high speed to deliver unrivaled musical performance.

ANALOGUE OUTPUT STAGES

The analog output stages are as important, they have a tremendous influence on the final sound quality. After d/a conversion by the R2R D/A modules the analogue signal is transported by fully discrete matched-transistor output stages; DC-coupled design with first class through-hole components. No SMD compon ents are applied in the analogue section. The high speed unique ACSS ((Audio-gd Current Signal System) output stages are non-feedback and current driven. Unique performance because almost all other designs need to convert the signal multiple times from and to current and/or voltage, resulting in less detailed and less transparent sound-stage The output buffers are single ended FET; two stages in parallel to reach very low output impedance. All output stages are in pure class A without (negative) feedback to achieve purest and a real live sound reproduction. The 4 OPA op-amp’s are DC servos, this way no coupling-capacitors are needed and DC output is automatically biased. The listener will be presented a strikingly transparent and neutral sound.

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.

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.

REGENERATIVE POWER SUPPLY

An integrated regenerative power supply is a proprietary electric generator built into the unit to avoid any noise from main power and deliver ultra-low noise and clean AC wave to feed the preamp. It will regenerate the main power and block noise from the power line, this way the preamp is able to reproduce the most neutral and analog sound you can imagine. First a transformer converts main voltage. DC conversion is done by class A PSUs power supplies.

A discrete balanced regenerative wave generator produces the new ultra-low noise wave form at 400Hz. The 400Hz frequency was chosen because they have better efficiency compared to traditional 50Hz and at this frequency, 400Hz, it will boost the sound to reproduce real and pleasant analog sound. The balanced gain amps with powerful output stages are driving the regenerative transformers to produce the extreme clean AC power. The extreme regenerated clean AC power is send to separate class A PSUs power supplies for both left and right channel. The discrete class-A DC power supply with high input impedance will avoid any noise and allow the amplifier stages to have low output impedance at very high speed and linear at frequency spectrum.

CLEAN POWER

The DAC consist of 3 tuned low noise, low flux leakage, R-cores transformers. In total 130W power to supply all digital parts and the left and right analog boards. The DC power is distributed over several separate power regulators. Analogue stages are pure class A low noise shunts; fed by 3 groups linear power supplies. Resulting in ultra-high speed and clean power for all individual parts.

TECHNICAL SPECIFICATIONS

pecifications tested by OS8 mode and already through sound tuned, we always improve for better real like , musical and analog sound ,improvement may result in changes in specifications and design without notice.
S/N Ratio	>120DB
THD+N	<0.03%
Gain	L mode : +13DBH mode : +26DB

Channels imbalance	< 0.05DB
Frequency Breadth (Whole unit)	20Hz – 20KHz (< – 0.25DB)20Hz – 150KHz (< – 3DB)
Output Level	Preamp Variable output : 20V max (XLR) / 10V max (RCA)DAC Fixed output : 2-5 V (XLR) /1-2.5V ( RCA)
Headphone amp Output Power (Balanced class A )	25 ohm: 15W 40 ohm: 10W 100 ohm: 4W 300 ohm: 1350mW
Headphone amp Output Power (Single-ended class A )	25 ohm: 4W 40 ohm: 2500mW 100 ohm: 1000mW 300 ohm: 350mW
Digital Input Sensitivity	0.4-1 Vp-p(75 Ohms, Coaxial)19 dBm (Optical)
XLR input impedance	XLR : 94K ohm
Support Operate Systems (USB)	Windows, OSX, Linux, ISO
Support Sampling	USB & IIS : 44.1kHz – 384kHz /32Bit DSD64-512AES/EBU and Coaxial mode: 44.1kHz – 192kHzOptical mode: 44.1kHz – 96kHz
Power Requirement	1 Version 100-120V AC 50/60 Hz2 Version 220-240V AC 50/60 Hz
Power Consumption	53W
Package Weight	Approximately 24KG
Dimensions	W430 X L480 X H123 (MM)
Accessories	AC power cord X1 USB cable X1 Metal remote X1

Comparison R27 Series

Model	R27 HE	R27 RE	R27 mk2
Headphone Amp	Yes	Yes	Yes
Preamplifier function	Yes	Yes	Yes
DAC Type	Discrete R2R	Discrete R2R	Discrete R2R
Amplifier Type	Discrete Balanced	Discrete Balanced	Discrete Balanced
Regenerative Power Supply	Yes	Yes	No
Step Down transformers	Yes	No	Yes
Gain Modes	L mode : +13DBH mode : +26DB	L mode : +13DBH mode : +26DB	L mode : +13DBH mode : +26DB
Preamp Variable output	20V Balanced	18V Balanced	18V Balanced
Headpone output	25 ohm: 15W	25 ohm: 10W	25 ohm: 15W
Master Clock Input	Yes, 50 or 75 ohm	Yes, 50 or 75 ohm	Yes, 50 or 75 ohm
Remote Control	Aluminium Remote	Aluminium Remote	Aluminium Remote
Color Enclosure	Silver / Black	Silver / Black	Silver / Black
Size	W430 X L480 X H123	W430 X L445 X H80	W430 X L445 X H80
Weight	24kg	12kg	12kg
Power Consumption	53Watt	42Watt	32Watt

Weight	22 kg
Dimensions	480 × 430 × 123 mm
Brand	Audio-GD

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DEMO: Audio-GD – R27HE – Regenerative PSU Balanced R2R PCM / DxD / DSD – Pre- & Headphone Amp