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Audio-GD HE-9 Full Balanced Pre Amplifier Preamp pre amp Pure Class A Balance Headphone Earphone Amplifier Balanced ACSS design

Audio-GD  HE-9 Full Balanced Pre Amplifier Preamp pre amp Pure Class A Balance Headphone Earphone Amplifier Balanced ACSS design
Audio-GD  HE-9 Full Balanced Pre Amplifier Preamp pre amp Pure Class A Balance Headphone Earphone Amplifier Balanced ACSS design
Audio-GD  HE-9 Full Balanced Pre Amplifier Preamp pre amp Pure Class A Balance Headphone Earphone Amplifier Balanced ACSS design
Audio-GD  HE-9 Full Balanced Pre Amplifier Preamp pre amp Pure Class A Balance Headphone Earphone Amplifier Balanced ACSS design
Audio-GD  HE-9 Full Balanced Pre Amplifier Preamp pre amp Pure Class A Balance Headphone Earphone Amplifier Balanced ACSS design
Audio-GD  HE-9 Full Balanced Pre Amplifier Preamp pre amp Pure Class A Balance Headphone Earphone Amplifier Balanced ACSS design
Audio-GD  HE-9 Full Balanced Pre Amplifier Preamp pre amp Pure Class A Balance Headphone Earphone Amplifier Balanced ACSS design
Audio-GD  HE-9 Full Balanced Pre Amplifier Preamp pre amp Pure Class A Balance Headphone Earphone Amplifier Balanced ACSS design
Audio-GD  HE-9 Full Balanced Pre Amplifier Preamp pre amp Pure Class A Balance Headphone Earphone Amplifier Balanced ACSS design
Audio-GD  HE-9 Full Balanced Pre Amplifier Preamp pre amp Pure Class A Balance Headphone Earphone Amplifier Balanced ACSS design
Audio-GD  HE-9 Full Balanced Pre Amplifier Preamp pre amp Pure Class A Balance Headphone Earphone Amplifier Balanced ACSS design
Audio-GD  HE-9 Full Balanced Pre Amplifier Preamp pre amp Pure Class A Balance Headphone Earphone Amplifier Balanced ACSS design
Audio-GD HE-9 Full Balanced Pre Amplifier Preamp pre amp Pure Class A Balance Headphone Earphone Amplifier Balanced ACSS design
$3,083.00
Ex Tax: $3,083.00
  • Stock: 10
  • Model: 4000077443128
  • Weight: 19.00kg
  • Dimensions: 50.00cm x 50.00cm x 18.00cm
  • SKU: 4000077443128
HE-9 (2019 Edition)
Regenerative power supply
True balanced CAST design
Pure Class A output (9W @ 40 ohms)
Preamp & Headphone Amplifier,
Three-position volume characteristic control, direct drive 80DB headphones without gain boost

Overview:


Built-in regenerative power supply

Three high performance R-cows with a total power of 260 W and over 100,000 UF of audio filter capacitors ensure the purity of the power supply

Separate Class A power supplies supply the regenerative power driver, left and right channel audio signal amplifiers independently

True balanced all-transistor feedback-free CAST current transfer circuit

Four pairs of precisely paired 150W high power tubes (up to 1200W total power) act as output stages for the headphone/preamp for high power Class A output

100-stage, four-channel, digitally controlled relay I/V switchable volume control to avoid channel imbalance and sound degradation

Super exponential wide-response volume control with 16, 25 and 31DB gain levels for easy adjustment with a wide range of high and low sensitivity headphones or speakers

Hi-end grade components, precision matched tubes, OCC cable

5 inputs: XLR X2 / RCA X2 /CAST X1 (Even with RCA or unbalanced CAST inputs, the HE-9 can still be converted to balanced CAST, XLR and RCA outputs.

Preamp Outputs : XLR / RCA / CAST

Headphone output : 4 pole XLR X1 / 3 pole XLR X2 / Single ended X1


Detail of the Current Conveyor Technology (CAST)

What is Regenerative Power :

When music is life, power is water. Pure water creates wonderful life, pure power reproduces heartfelt sound.

Regenerative power is like having a private generator built into the machine.

It filters out the maximum amount of interference from the power line and provides super pure power to the audio amplifier, restoring a very undiluted and analogue sounding signal to the audio system and the user.

The regenerative power supply is designed so that 120V / 220V AC power is converted to DC power via a regenerative power input transformer, and then to a Class A parallel regulated power supply for the regenerative waveform generator and driver.

A balanced regenerative standard waveform generator produces an ultra-low distortion 50Hz waveform, which is balanced by a gain amplifier and a powerful driver stage to drive the two regenerative output transformers to produce a pure, stable voltage and frequency supply, which is then used to independently power the left and right channel audio amplifiers from separate Class A parallel regulated power supplies.

Both the regenerative waveform generator and driver are powered by the Class A regulator, making their operation immune to mains variations and interference.

The Class A shunt voltage regulator has a very high input impedance to prevent interference from entering the audio circuitry via the mains supply, and also to avoid crosstalk between the left and right sound signals through the power supply to improve separation. The low output impedance provides excellent linearity and speed, making it an excellent power supply regulator design.

Audio-gd's arguments for regenerative power supply design.

1, The pure analogue regenerative standard waveform generator has much lower distortion than the digital synthesis generator, as demonstrated by internal design analysis and practical testing of the AP SYS-2722.

2, The digital driver stage can have a higher power conversion efficiency, but the fully analogue driver stage has more analogue flavour.

3, The 400Hz regenerative waveform frequency has a higher power conversion efficiency, and the 50Hz regenerative waveform frequency is further away from the human hearing zone than 400Hz, resulting in a more mellow and natural sound quality.

Audio-GD-HE-9-Full-Balanced-Pre-Amplifier-Preamp-pre-amp-Pure-Class-A-Balance-Headphone-Earphone-Amplifier-Balanced-ACSS-design-4000077443128

ACSS:

The HE-9 is a truly balanced headphone and preamp design, using the latest CAST technology to advance the sound quality of the XLR input to be as good as CAST.

The HE-9 may look complex, but it is in fact the simplest design in the world, with most of the components used for power processing. The simple and short signal processing channels result in a dramatic improvement in sound quality with very little audio coloration.

The HE-9 uses a single stage CAST amplifier circuit with extremely low distortion, whereas an ordinary OPA op-amp uses a two stage amplifier circuit inside. The device is mounted directly on the motherboard for better sound quality.

The CAST circuit is a transistor amplifier with no feedback at all. Many audiophiles know that a negative feedback design provides better test specifications, but a feedback-free design provides better listening. This is a contradiction between traditional circuits. But the CAST circuit breaks new ground by offering extremely low tone coloration, a very neutral and natural sound with very low distortion and excellent linearity. As a result, it reproduces better dynamics and richer detail without sounding rough and dry.

All gain stages operate in current transfer mode, all transistors operate in Class A and use a Class A power supply.

The feedback-free diamond-shaped output stage is equipped with two pairs of 150W high power tubes per channel and operates at high bias Class A. The output impedance is only 1 ohm.

All components of the HE-9's balanced four channels are precisely matched for installation.


Volume control design:

The HE-9's volume control is a departure from other technologies. Conventional volume control involves placing a volume control potentiometer at the input of the amplifier to attenuate the signal, which can cause loss of detail and channel imbalance with low quality potentiometers.

In the HE-9, however, we have used an I/V conversion type of volume control, where the volume control is like a variable passive I/V converter fitted to the output of the CAST amplifier, where it works on a current signal rather than a voltage signal (like the passive I/V converter output from the R-2R's DAC chip), resulting in a very flat frequency response and no loss of detail. No detail is lost.

The consistency of the volume control is the key to the performance and sound quality of a truly balanced amplifier. It is essential that the signals of the four channels are precisely controlled. If the + and - signals of the balanced signal are not precisely controlled, the balanced output will produce severe distortion and make the sound quality and performance even worse than a normal unbalanced amplifier, wasting the design and high cost of a truly balanced amplifier.

The HE-9 uses a four-channel, digitally controlled, relay-based volume control, which is controlled by switching a high-precision DALE resistor, eliminating channel imbalances and inaccuracies in the + and - of the balanced signal, and achieving the best possible sound quality and performance. Working in the current field, there is no need to worry about the sound quality caused by the contacts of the relay.

The HE-9 features a 100 level exponential wide response volume control, which is easily adjustable with a wide range of high and low sensitivity headphones or speakers. As the user adjusts the volume, the different relays switch resistors so the output may have a slight relay switching sound, which will disappear once the volume is stopped.


Super exponential wide response volume control


Audio-GD-HE-9-Full-Balanced-Pre-Amplifier-Preamp-pre-amp-Pure-Class-A-Balance-Headphone-Earphone-Amplifier-Balanced-ACSS-design-4000077443128


Corresponds to normal knob volume range

Audio-GD-HE-9-Full-Balanced-Pre-Amplifier-Preamp-pre-amp-Pure-Class-A-Balance-Headphone-Earphone-Amplifier-Balanced-ACSS-design-4000077443128


Shielding:

The HE-9 completely isolates the four sections of the left and right amplifiers, the regenerative power driver and the secondary power transformer, even the 120V/220V incoming cables are separated by a thick aluminium plate.

The HE-9 uses a heavy, all-aluminium chassis to prevent eddy currents from being conducted through the chassis and affecting the sound quality.

Components:

The HE-9 uses all high quality audio components, including DALE resistors, WIMA capacitors, custom NOVER (UK brand) capacitors, audio grade input and output sockets and gold plated RA power sockets, all of which are precisely matched to the four channels of the HE-9's balance.


HP/PRE switch :

Selects the HE-9 from the headphone output (display H) or the preamp output (display P).

Gain switch :

L: 16DB gain, suitable for headphones above 100DB or for preamp use.

H: 25DB gain, suitable for headphones up to 80-100DB.

S: 31DB gain, suitable for use with low sensitivity headphones of 80-100DB when the source is only 2-3V @ XLR or 0.7-1.5V @ RCA for low output levels or according to your personal preference (only RCA and XLR are available).

With our new gain control technology, no in-line switches, relays or amplifier parameters are changed when switching between gains, so the sound quality is exactly the same at different gains of H and L. The user only needs to select the appropriate mode to make the volume control more convenient for personal adjustment.


Audio-GD-HE-9-Full-Balanced-Pre-Amplifier-Preamp-pre-amp-Pure-Class-A-Balance-Headphone-Earphone-Amplifier-Balanced-ACSS-design-4000077443128Selector switch :

Selects HE-9 inputs 1-5.

Volume knob :

Selects the HE-9 volume.

 

Sets the function of HE-9:

When IN5 is entered, the volume is turned down to minimum and then the volume knob is turned down one notch to enter the setting mode, one of the three displays on the display will flash to indicate that the function of this position can be changed. At this point, turn the volume knob down one more notch to exit the setting mode.

Each time the "INPUT" button is pressed, the flashing display will move one position to the right.

By pressing the "Gain" button, the flashing display will be changed, with 0 for the function to stop and 1 for the function to take effect.


Audio-GD-HE-9-Full-Balanced-Pre-Amplifier-Preamp-pre-amp-Pure-Class-A-Balance-Headphone-Earphone-Amplifier-Balanced-ACSS-design-4000077443128


The first display is the remote control function setting, mainly for the remote control volume function, when set to 0, the volume changes by one stop when the remote control is pressed. When set to 1, the volume will increase or decrease continuously when the remote button is pressed continuously. If the machine is susceptible to interference from other devices, please set this function to 0.

The second position is the automatic screen darkening setting. When set to 0, the display will light up when the machine is switched on. When set to 1, the display will automatically switch off after about 10 seconds of no operation, leaving only one LED to show that the machine is powered on.

The third position is the volume memory setting, when set to 0, the volume does not use the memory function. When set to 1, the volume has a memory function and will remain at the volume level of the last time the machine was switched off, even if the machine is switched off and then switched on again.


Audio-GD-HE-9-Full-Balanced-Pre-Amplifier-Preamp-pre-amp-Pure-Class-A-Balance-Headphone-Earphone-Amplifier-Balanced-ACSS-design-4000077443128Audio-GD-HE-9-Full-Balanced-Pre-Amplifier-Preamp-pre-amp-Pure-Class-A-Balance-Headphone-Earphone-Amplifier-Balanced-ACSS-design-4000077443128Audio-GD-HE-9-Full-Balanced-Pre-Amplifier-Preamp-pre-amp-Pure-Class-A-Balance-Headphone-Earphone-Amplifier-Balanced-ACSS-design-4000077443128

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