Real Balanced ACSS Preamp & Headphone amp
How to choice
between Master-5 and Master-6?
The Master-5 and Master-6
had same PCB design. The Master-6 output stage without limit so
can offer large output power.
If your headphones are not difficult to drive, the Master-5 is
ok for the choice.
If you have some difficult drive headphones, choice the Master-6
can offer large output power.
Input: XLR x2 / RCA
x2 / ACSS x1
with the single end ACSS or RCA input, Master-5 can conversion
to XLR and balanced ACSS and RCA output
from preamp , and conversion to balanced and single end
Output: XLR x1 / RCA x1/ ACSS x1
Headphone amp output: 4pins XLR X1 / 3pins XLR X2 /
Single end X1
USD1450 (Excluding shipping cost)
Weight: Approximately 16kg
Dimension: W430 X L430 X H93(MM)
Accessories: Power cable x1
Master-5 can work with all sources and power amps in the world, but its ACSS output can only work with
audio-gd Master series power amps.
Master-5 Preamp/HP button select between RCA / XLR of the preamp
and headphone amp output, the ACSS signal output always
Master-5 is a class A amp, don't cover the vents please .
Advice: 1, Master-5
has extremely high fidelity; its SQ is neutral. It can show how good or
how bad a recording or source is.
2, It is better not to stack gear on top of each other, if necessary to
stack Master-5 on other gear, place a paper or other insulating
material on top of other gear, because Master-5 has conductive aluminium
3, Attention must be given to matching suitable power cable and signal
A review of our
preamp and power amp from John Darko.
reviews in headfi.
Master-5 is a true balanced design applying the newest ACSS
design which can improve the XLR connection to sound as good as the
ACSS connection. They 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.
Master-5 applies ultra-low distortion
single stage ACSS amplifier and soldered directly on the motherboard.
It is a fully class A preamp / headphone amp and applies class A power supplies.
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, all transistors
work in class A mode.
The Master-5 output buffers are
Non-feedback, for low impedance and ultra-low distortion , we applied
two pare MOSFET (K214/J77) and transistors
, the output
impedance is only 1 ohms , it can drive most headphones and amps
as well .
Master-5 has all components of four channels
exactly matched before installation.
Three special transformer are used to supply power
separately for the audio and control circuit.
Master-5 uses 8 groups of
high-quality class A parallel connection PSU, four double-stages for
dedicated DC supply.
class A parallel connection PSU has very high input impedance to avoid
pulse through the PSU from affecting the preamp and low
output impedance with very fast speed and high linear, so it is a very
Master-5 applies two linear PSUs for the
display and control parts, avoid the disturbances through power line
from affecting the amplifier.
Master-5 can input
not only XLR balanced signal or RCA unbalanced signal, but also the
top-grade ACSS current signal. It can also output RCA signal, balanced
signal, ACSS current signal to the power amplifier. Using RCA input, Master-5 can convert to balanced ACSS signal and output real balance
signal from XLR and ACSS.
Master-5 can output RCA, XLR and ACSS at the same time
in preamp output model , in headphone amp model, Master-5 can output
XLR ,single end for headphone, and ACSS for power amp at same time.
The input channels of Master-5 adopt separated
shielding method. When switching, the idle signal lines linked to the
equipment and the ground wire are completely disconnected. The idle
input ports of the equipment are shielded. In that case, the sound
quality won't be affected even with more connected equipment.
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 still cause the detail lose. Whatever
quality volume pots, must cause the S/N worst .
the Master-5 , 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
diamond non-feedback buffer output stages offer the
very low output impedance .
Mark Levinson also knows that current volume control has great
benefits, so in their Top End preamp NO.32 volume control, they use
many components to change the signal to current signal (I), then
implement the volume control
, and then change back
to voltage signal (V) again. But Master-5 is simply a more complete
work in terms of the current signal, and technically, it is superior
to conventional technology.
The less conversion bring much neutral sound .
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. .Master-5 has total four channels through changing the
DALE resistors to control the volume for avoid channels
imbalanced ,achieve the best performance and sound quality of
users select between 99 steps exponential characteristic volume
control and 70 steps linear characteristic volume control,
whatever volume control allow users smooth to control the volume
Master-5 has complete separation of left, right
amplifier channels, power supply, and transformer.
Master-5 uses heavyweight all-aluminum alloy chassis to prevent the
eddy current of transformers from interfering on circuit board.
Master-5 applies optical couple isolation for the MCU and the
control implementations to prevent the MCU affecting the audio parts.
Uses all audiophile grade
components, including DALE resistors, WIMA & SOLEN caps, custom
order NOVER (UK brand) caps, all audiophile grade input & output
sockets (Neutrik ) and gold IEC socket. Master-5 all parts of four channels had exact match before install.