Different to 2015 Edition:
The 2019 Edition upgraded and has two
different volume control characters, can perform high and low
gain modes without change the amp's parameter so without effect
on sound quality. And addition a super gain control.
The L gain mode has 16DB gain,
for drive the headphones which have over 100DB sensitivity or work
The H gain mode has 25DB gain,
for drive the headphones which have 80-100DB sensitivity.
The S gain mode has 31DB gain,
for drive the headphones which have 80-100DB sensitivity but with
the low output level sources
(Available on RCA/ XLR inputs ).
Connect with KRELL amplifiers:
HE 9 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
Pin 1, GND
Pin 2, Hot
Pin 3, Cold
Pin 4, GND
have lower gain versus audio-gd Master series amplifiers when
using the CAST connection, so customers can custom order the
HE 9 to have higher ACSS output gain if expecting to connect
to KRELL amplifiers.
regenerative power supply history
The HE series products had the longest term of design and test
in audio-gd history . Even though audio-gd
had release the regenerative power supply products since 2006, and Mr.
Kingwa had publish the article in the <Radio & TV> magazine explain
the technology detail .
The HE series products had finished
the design in the New Year of 2014 , we were plan to release
them in the date of audio-gd 10 anniversary , but for got
the best sound quality and performance, we have even 3 times
change the full design for made the compare, and compare different power frequency
and voltage, create the longest design term record.
The HE series products have better detail
and dynamic reproduce ,blacker backstage ,better focus and
larger sound stage , but the sound is better analog .
The right saddle must is set on the right
horse ,if you had not enough good system units, and had not
enough cable match experiences, don't waste the money on HE
Please note the HE series products are upgrade
from Master series, even though the price had a big rate
increased but the sound quality had not same rate improved.
different between HE-1 and HE-9:
HE-1 is a decent preamp , HE-9 is a preamp with headphone amp,
their sound quality is close, if customers want the headphone
output, choice the HE-9 is proper.
Built in regenerative power supply
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
,Left and Right channel
audio signal amps .
Total applied 8 pcs exact matching 150W transistors ( In total
1200W ) as the
output stages for implement large class A output
Uses most Hi-end grade parts and exactly matched transistors, OCC
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 very high headphone / speaker without change the
16,25,31DB in total 3
type gain modes can drive the low sensitivity headphone very well.
5 groups input:
RCA X2, XLR X2, ACSS X1
Preamp output :
XLR / RCA / ACSS
Headphone amp output: 4pins XLR X1 / 3pins XLR X2 /
to read the ACSS technology :
Detail of the Current Conveyor Technology
What's the regenerative power supply :
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.
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 and steady 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.
on the regenerative power supply design points :
Through analyzed the AP SYS-2722 ,do a lot practises ,test and
listen , full analog design of the
regular wave generator have much lower distortion than the
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
HE-9 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-9 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.
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-9 has all components of four channels
exactly matched before installation.
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 .
the HE-9 , 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
FET non-feedback buffer output stages offer the
very low output impedance .
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.
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
HE-9 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
HE-9 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-9 uses heavyweight all-aluminum chassis to prevent the
eddy current of transformers from interfering on circuit board.
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-9 all parts of four channels had exact match before install.