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Audio-GD - HE-8 Balanced R2R 4x PCM1704 DAC (PCM 32bit 384kHz)
| Brand: Audio-GD |
| Product Type: Digital Analogue Converters |
HE-8 Balanced R2R 4x PCM1704U-K DAC
- Use of a servo-stabilised discrete power supply to power the digital circuits, ensuring extremely low noise and low operating temperature. The clock and analogue circuits are always powered by a Class A regulated power supply to achieve the best sonic results.
- Analogue sound reproduction can be selected from the front panel.
- All digital inputs and parts are isolated from the analogue parts.
- Displays the sampling rate of the input signal.
- The 10MHz clock input allows an external clock generator to be used.
- The FPGA operates using a parallel data processing mode. The I2S signal enables serial data transmission. Each bit of data requires one clock cycle. A frame of data from the left and right channels requires 64 clock cycles. Stability over 64 clock cycles is therefore necessary. Parallel mode requires only one clock to transmit and process the 32bit data from the left and right channels, which considerably improves processing speed and stability. I2S input data (USB and HDMI) is reorganised into two sets of parallel 32bit data as soon as it is input. Once the SPDIF signal has been demodulated, it too is sent to the next level of processing, via two parallel 24bit data sets. The parallel processing mode results in a clearer, more neutral sound, with better dynamics and a more analogue signature.
- The clock management design of this architecture makes the clock operation more stable, resulting in greater transparency and detailed sound.
Multi-Functional Display
A new display type has been added to the R8 mk3. Both input and sample rate are now being displayed. (2 line multi-function display)
Firmware Update Port
On the back-panel of the unit an update port is available to quickly update the firmware using the USB Blaster (included).
FPGA Signal Processing
The internal hardware design is fully controlled by complex software. Software in the FPGA can easily be upgraded offering new capabilities or improve the performance of the device without replacing any hardware.
Technical Specifications
| Technical Specifications | |
|---|---|
| Product type | R2R DAC |
| DAC Chips | 4x PCM1704UK |
| Inputs | 1x AES/EBU 1x Optical Toslink 1x Coaxial 1x BNC 1x I2S via HDMI LVDS 1x USB-B 1x Port for software update |
| Outputs | 1x Single-ended RCA 1x Balanced XLR 1x Balanced ACSS |
| Signal-to-noise ratio (SNR) | > 120dB |
| Output impedance | < 5Ω |
| Output level | RCA : 2.5V XLR : 5V ACSS : 2+2mA |
| Frequency response | 20Hz – 20kHz |
| Total harmonic distortion (THD) | < 0.01% |
| Input sensitivity | Coaxial 75Ω : 0.5Vp-p Optical : 19dBm |
| Compatible OS (USB) | Windows, OSX, Linux, ISO |
| Supported sampling rates | USB, I2S : PCM up to 32bit 384kHz Coaxial, Optique : PCM up to 24bit 192kHz |
| General | |
|---|---|
| Supply voltage | 220-240V AC 50/60 Hz |
| Consumption | 48W |
| Dimensions | 430 x 445 x 80mm |
| Weight | 12kg |
| Color | Black |
| package | 1x AUDIO-GD HE-8 1x Power cable 1x USB cable 1x Remote control |
NOS & OVERSAMPLING MODE
The R8 offers several Oversampling or NOS (Non-Oversampling) modes. If you wish to choose Oversampling, simply select the value “O”. If you want to choose the NOS then you have to choose the value “N”. You can then select one of the following modes to adapt the playback to your listening experience
ULTRA FAST SIGNAL PROCESSING
FPGA stands for Programmable Array Logic. Nowadays the FPGA is widely adopted in audio devices. The internal hardware design is fully controlled by complex software. A huge advantage is the fact the software in the FPGA can easily be upgraded offering new capabilities or improve the performance of the device without replacing any hardware. Versatile and future proof design.
- High performance SPDIF interface, replacing traditional less good performing SPDIF interface chips like DIR9001, WM8805 or AK411X,etc.
- Full re-clocking process with FIFO design applicable on all inputs. This way the output data keeps fully synchronized with the clock signal to reject any jitter.
- Built in 2X, 4X and 8X oversampling and digital filters and on top of this 4 different true NOS (only analog 6dB filtering) modes. To completely configure the sound according to your taste.
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.
ACSS – Current Amplification
Audio-GD has developed an advanced current-driven amplifier technique. Also known as ACSS, Audio-GD Current System Signal. This special technique ensures that the signal travels a much shorter path and that ensures a more transparent, faster and more neutral reproduction. A similar technique is used by, for example, KRELL. The Current Conveyor technology mostly components are the current mirror. The Current Conveyor technology isn’t a new technology, at 1966 , professor K.C. Smith and A.S.Sedra publish the concept “current mode analogue circuits “ .
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.
