Comparison table 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

HIGHLIGHTS

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 up gradable 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

TECHNICAL SPECIFICATIONS

specifications 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 : 18V max (XLR) / 9V 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: 4W40 ohm: 2500mW100 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	42W
Package Weight	Approximately 12kg
Dimensions	W430 X L445 X H80 (mm)
Accessories	AC power cord X1 USB cable X1 Metal remote X1

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 components 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.

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.

Peso	12 kg
Dimensioni	445 × 430 × 80 mm
Brand	Audio-GD

1 recensione per Audio-GD – R27 mk2 – Regenerative PSU Balanced R2R PCM / DxD / DSD – Pre- & Headphone Amp

Valutato 5 su 5

Tom (proprietario verificato) – Gennaio 6, 2024

I am quite new to the world of high end audio, but the integrated DAC/Preamp/Headphone units from Audio Gd caught my attention just over a year ago and seemed to be the at-home headphone solution I needed.

After liaising with Jos about which model to get, I decided to go for the R27 mk2 with the silver wiring upgrade, and the high gain option to give me more flexibility for different headphones. The guidance initially given proved very useful and I can honestly say the unit has exceeded my expectations and I expect It will stay with me for sometime as I build a system around it. I have just three headphones currently but all have paired well with the unit (using a laptop as a source via the USB input). Firstly, the Hifiman He6se – a headphone known to be difficult to power – sounds great on it, and with the high gain modification I typically have the volume at 30-35/99 most of the time, so still plenty of headroom. The sennheiser HD600 stays in the low gain area, around 40-50/99, and the Beyerdynamic T5 3rd generation lower than this at 20-25/99. All three sound great, and even the Beyerdynamic – a headphone that usually doesn’t need an amplifier – sounds much better than on my portable sources.

Furthermore, I have even tried iems (!!??) on this out of the single ended input. Now, for some you don’t get a lot of range on the volume, but there was no audible hiss from the Letshuoer S12, 7hz Timeless, Fiio FHE Eclipse (Crinacle colaboration) and the Fiio EM5. All four sounded great, especially the two planar iems that seemed to like the power on offer!

My one suggestion for Audio Gd I think… would be to have a third gain option, so Low, medium and high. This way a user could easily use a range of iems with the unit too, although I think even in the low gain option you still have some flexibility based on my experience.

I am now looking for partnering gear and I am looking forward to the journey! But best of all has been the great customer service shown by Rob and Jos. Buying a piece of high end gear such as this is a big investment and can be daunting for the uninitiated like myself, but Rob and Jos have been great at providing after service support and answering any questions I have.

I can heartily recommend the Audio Gd R27 Mk2 with the silver wiring and high gain options, and can definitely recommend Magna Hifi as a go to place for audio equipment.

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Prezzo prodotto:	€2.229,00
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Audio-GD – R27 mk2 – Regenerative PSU Balanced R2R PCM / DxD / DSD – Pre- & Headphone Amp

Color

Comparison table R27 Series

Model

R27 HE

R27 RE

R27 mk2