Price: USD6660 (1
set with 4 blocks .Exclude shipping cost . )
1,The user that purchased and using audio-gd Master series power amp
can provide the series number when place the order .
2, The product has burn in 500 hours before shipping cause the
leadtime is long .)
3, The DC power cable length 50CM in default , if need longer cable,
please custom order .
4, The rear of the regenerate power supply chassis built with organic glass, no
fonts on it, if care , don't order it please.
Recommend match with
HE-1 preamp with the most reallike sound :
Compare to Master 2H:
tried two pair Master 2Hs working in Bi-Amps mode, compare to one
pair HE-2MK2 working in the normal mode, in our opinion that the
HE-2MK2 still better sound quality overall than the two Master 2Hs.
About the DC blocker :
Because the product has the low impedance transformers design , if
the power line (120V or 230V) has serious disturb , usually will has
the low voltage DC in the power line, cause the transformers have
the vibration and cause the noise.
Even though in the same serious disturb in
the power line , the high impedance transformers design can without
vibration and noise , for example the R core, EI core or high
impedance design toroidal core transformers.
But for the power amp, the high impedance
transformer design has effect and degrade on sound dynamic, bass
impact and control .
Because the serious disturb power line is
rare, based on the customers feedback, it has around 10% users
encounter with serious disturb , so our power amps have not include
the DC blocker .
For avoid the sound quality degrade, the
HE-2 MK2 can not custom order built in the DC blocker, if users have the
DC disturb cause the transformers' hum, please order the external
high quality outlet which built the DC blocker .
About the external power processor :
Because the product built with regenerate power supply , we don't
recommend connected to the active external power process like external
regenerate power processor, isolate power transformers, voltage
regulator ect, In the extreme case even the power has serious
interrupt, use a good quality power filter
outlet is enough .
Separate blocks regenerate power
supply (The regenerate power supply for the gain boards )
Fully balanced design, the gain stages and pre-driver stages work in
pure class A, built with discrete analog stages without any OPA or
coupling caps in the signal channels.
The output transistor stages have supper excellent linear, it
sound like the pure class A design but without the high heat of the
pure class A design .
2 analog inputs: XLR / ACSS
Applies 80 pieces of ON Semiconductor transistors.
Each channel supports 30W pure class A and 250W class A (8 Ohms) output.
The capacitance of the whole machine reaches as high as 260,000
uF, with 6 unit transformers (Over 2000W) and separate power
supplies for the right channel and left channels.
A total of 8 groups of high-quality class A parallel connection
Applies all audiophile grade components, including DALE
resistors, WIMA caps, custom order NOVER (UK brand) caps, all
audiophile grade input & output sockets and gold IEC socket.
The non negative feedback output
drive stages had applied "Linear Fidelity" technology :
The HE-2 MK2 had applied the
"Linear Fidelity" technology on the output drive stages . The output
drive stages had not negative feedback but can keep the distortion
low and steady, and had the ultra excellent linear
In some lot power amp designs, the
distortion had big different level on different power output level ,
even on one power output level, the full frequency band's distortion
level had quite different , especial the low and high frequency .
The blue line of below diagram show the
distortion to frequency at 8 ohm 20W output of an well known power
amp which worth around USD10k.
The below diagram show the most
musical instrument frequency bands . The frequency band had cover
from 20Hz to 4KHz .
Different distortion must effect on the
sound . For example, if playing piano music recorder, cause by the
larger different distortion on the frequency band, you can hear the
low frequency band like playing a brand A piano, the middle
frequency band like playing a brand B piano, and the high frequency
brand like a brand C, the music recorder like the different brand
pianos edited together.
The negative feedback applied,
most is for reduce the distortion.
Some people dislike the
negative feedback design on the power amp, it reduce the distortion
but make the listen unpleasure.
The negative feedback power amp
had good distortion result on emulational load measure, but while
connect the real speakers, the electric potential of the speaker can
through the feedback loop feed to the amp input stages cause the
The negative feedback power amp
even reduce the distortion , but the distortion increase while
output power increase, this cause the larger dynamic music sound
become harsh and fire to your face while listen the music.
Usually the non negative feedback design has high distortion and
difficult to control, especial the drive output stage which is work
under strong current state.
In the HE-2 MK2 design, the gain
stages have applied the ACSS technology, it is the non negative
feedback design but it's native advantage has very low distortion.
The output drive stages had
applied the " Linear Fidelity " technology .
overall design in the HE-2 MK2 is non negative feedback design.
From the diagrams, the
amp has quite flat and steady distortion on the frequency band from
20Hz to 5KHz, keep the same sounding character while playing the
musical instruments .
The distortion roll off a
lot start at 5KHz, even lower than some amps which is depend on the
negative feedback , it obvious show the supper linear performance of
Compare the diagram, the upon
diagram has 0.015% distortion at 20KHz , the below diagram has
0.002% distortion on 20KHz.
The ultra low distortion had not
depend on the negative feedback, but depend on the ultra linear of
the amp, so it's sound very transparency and analogue.
On the different output power
level , the amp has similar distortion level, while listen with
softer and dynamic music, it offer the same sound character
without harsh .
Below diagrams had show the
distortion on the HE-2 MK2.
THD+N at 8 ohm 10W: approximately
THD+N at 8 ohm 50W: approximately
THD+N at 8 ohm 100W: approximately
Regenerative power supply :
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 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 :
1, 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 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