Audio-GD HE1 mk2 – Demo Model – Regenerative PSU Balanced Preamplifier (RCA, XLR, ACSS)

Shipped since July 2019, the unit has upgraded the transformers , can power on long term.

Connect with KRELL amplifiers:

HE-1 is compatible with KRELL amplifiers CAST inputs.

A cable can be made with one side connecting to Master 1 ACSS outputs, other side to a  KRELL amplifier CAST inputs.

• The ACSS output pins:
  Pin 1, GND
  Pin 2, Hot
  Pin 3, Cold
  Pin 4, GND

KRELL amplifiers have lower gain versus audio-gd Master series amplifiers when using the CAST connection, so customers can custom order the Master 1 to have higher ACSS output gain if expecting to connect to KRELL amplifiers.

New 2019 verSION

• The analog circuits design is slower develop compare to the digital design. Especial the excellent design.
• HE-1 released since 2015, we have not change its design , we always like to upgrade the design but we can’t .
• Now we are release the new version, the most improve is applied the single polarity FET buffer stages in input and output, which is had a bit lower distortion and improve on the sound quality.
• The Single polarity FET stages are the non feedback design and applied the Toshiba K170 , which is even had money but can not buy from market nowdays.
• The others improve on power supplies for less noise and darker black back stage.
• The control parts let  users can disable the input short by themselves without soldering work.

SUMMARY

Built in regenerative power supply

• Fully balanced class A design built by discrete analog stages without any OPA or coupling caps in the signal channels.
• Non- feedback ACSS analog output stage.
• Uses three R-core transformers (In total 260W ) and more than 100,000uf audio grade NOVER capacitors are used to ensure ample and smooth power delivery.
• Separate class A PSUs power supply for regenerative drivers and audio signal amps .
• Four-channel 100 steps digitally controlled relay-based volume control avoids channel imbalance and improves sound quality.
• Supper Exponential Volume Characteristic, easy match the volume with different power amp and speaker .
• 5 analog inputs:  RCA X2, XLR X2, ACSS X1 ( Even with RCA or XLR inputs, the output still had ACSS aviable)
• 3 outputs:   XLR / RCA / ACSS (They can connect 3 units power amp  simultaneously)
  
  

Current Conveyor Technology

What’s the regenerative power supply :

While audio is life , the Power supply is water , Pure water create the wonderful life ,clean power supply reproduce the beautiful sound .

The regenerative power supply like a proprietary electric generator built in the unit.

It can block most disturb from the power line , supply the ultra clean power supply for the audio amps , reproduce the most neutral and analog sound like audio signal for the system and the users.

In the regenerative power supply design, the AC power through the regenerative input transformer , conversion to DC power ,through the class A PSUs power supply for the regenerative wave generator and driver stages .

A balance regenerative regular wave generator produce the ultra low distortion 50Hz wave ,through the balance  gain amps and the strong  output stages , drive the regenerative transformers produce the clean AC power supply feed to the separate class A PSUs power supply for the L and R channel preamps .

The class A parallel connection PSU has very high input impedance to avoid disturb through the PSU from affecting the signal parts and low output impedance with very fast speed and high linear,  it is a very clean power supply.

Audio-gd on the regenerative power supply design points  :

1, Through analyzed the AP SYS-2722 , full analog design of the  regular wave generator have much lower distortion than the digital generator.

2, Digital drive stages  have higher efficiency , but full analog drive stages  have much better analog sound like .

3, 400Hz regenerative wave have higher efficiency , 50Hz regenerative wave had much far away the human ears sensitivity area than the 400Hz, boost the sound have much better analog sound like.

ACSS

HE-1 is a true balanced design applying the newest ACSS design which can improve the XLR connection to sound as good as the ACSS connection. The HE-1 seem complex , but in fact they are the most simple design the world has ever had , their a lot components to process the power supply. The simplest and shortest signal journey brings out the most neutral and least colored sound.

HE-1 applies ultra-low distortion single stage ACSS amplifier , an OPA already had built in two stages amplifier. they are soldered directly on the motherboard.The ACSS is a non-feedback technology made with discrete amplifiers. Most people know the global feedback design can offer better specs in test measurements, and non-feedback can’t do well in test measurements but can offer better sound for the human’s ears. Here is a conflict of the classic circuits.

But the ACSS opens a new field, it can offer a least coloration sound which is more neutral with very low distortion and high linearity. So it can retain the dynamics, detail and neutral sound but not sound bright or harsh. All signal gain is in current area, all transistors work in class A mode and applies class A power supplies.

The XLR /RCA output buffers are Non-feedback, for low impedance, we applied a two-stage parallel connection, the output impedance is only 10 ohms.
HE-1 has all components of four channels exactly matched before installation.

Volume control

The volume control is also different from conventional technology. Conventional volume control technology is the volume control implement in the analog amp input stage through a volume pot to reduce the signal  . The volume pots quality effect the sound quality direct , the low quality volume pot cause lost the detail and channels imbalance cause the soundstage distortion  . Even the high performance volume pot ,in the attenuation then gain the signal mode ,still cause the detail lose and cause the S/N worst .

In the HE-1 , we applied the I/V conversion volume control , the volume control just  a variable passive I/V conversion place at the ACSS amp output , where the output is the current signal, not the voltage signal. The volume control is I/V conversion, and the volume depends on the current (I) conversion to the voltage (V). (Like R-2R D/A chips output passive I/V conversion)  It can keep the signal frequency band flat and not lost any detail. It can’t degrade on sound quality in every volume level . After the volume , there are four groups  FET non-feedback buffer output stages offer the very low output impedance  .

The volume control quality is much important in the real balance gear . It must guarantee the four channels signal control exact to achieve the performance of the real balance gear .  If the cool and hot of the balance signal can’t guarantee exact, the balance output will has large distortion cause the sound quality and performance even much worst than a single end gear , waste the  balance gear  design and the cost.

In HE-1 is applied a four channels digital control relays based volume control, through changing the DALE resistors to control the volume for avoid channels imbalanced ,achieve the best performance and sound quality of the gear.

HE-1 have 100 steps volume control, applied Supper Exponential Volume Characteristic, easy match the volume with different power amp and speaker .While change the volume, the different relays break or close, it may had slightly switch sound on output and disappear while stop change the volume.

Supper Exponential volume characteristic    The Volume steps comparison to normal volume knob

Enclosure

HE-1 has complete separation of left, right amplifier channels, regenerative drivers and transformer, even the 230V / 120V power input lines had shield in the two thick aluminum boards .

HE-1 uses heavyweight all-aluminum  chassis to prevent the eddy current of transformers from interfering on circuit board.

Components

Uses all audiophile grade components, including DALE resistors, WIMA caps, custom order NOVER (UK brand) caps, all audiophile grade input & output sockets (Neutrik ) and gold IEC socket.  HE-1 all parts of four channels had exact match before install.

FEATURES

Auto dark the display:
While the unit selected input 5 and the volume on 0 step, turn the volume knob lower 1 step, the left second display show „1“ mean the auto dark active, the display will dark after you stop operate all buttons .
If you want disable the function, While the unit selected input 5 and the volume on 0 step, turn the volume knob lower 1 step to let the left second display show 0 .

Display inform:
Left first mean the input channel number .
         Left second mean the auto dark function.
         Another two display mean the volume level, number higher volume is higher .