AudioValve Assistent 100 User Manual

Audio Art Magazine

Equipment collection

AudioValve

Assistent 100 (Top-level Special Edition)

Exquisite Delight in Superior Sound

Integrated Valve Amplifier

The output power of each sound channel is 110W (8Ω load). The used valve: EF86 × 2, ECC82 × 2, QQE 03/12 × 2 and 6C33 × 4. Input terminal: 5 sets of

XLR and 5 sets of RCA. Output terminal: 1 set of TAPE OUT (RCA). Damping: 20. Input impedance: 47 kΩ. S/N ratio: > 80 dB. Total harmonic distortion: <

0.15 % (- 50 watt). Frequency response: 5 Hz - 60 KHz. Dimensions (WHD): 550 × 170 × 450mm, weight: 45 kg. Import general agency: Dian-Li (03-

2127378).

Written by Shu Shihao

Helmut Becker, the boss of AudioValve, is a fairly “distinct” designer. The
products designed by him never follow the trend but each piece still can
manifest his insightful opinion about sound. Though it always takes longer time for

this company to promote new products, the waiting is definitely worthwhile.

Take Assistant 100, the subject of this

review, for example, Helmut Becker
employs the rarely seen 6C33 valve
and adheres to his distinct design
principles, to produce through delicate
work the only two integrated
amplifiers in the world till now.

First use of gauge design

This time, we went to visit Mr. Chen,
who is the shopkeeper of T&V Pro

Audio in Tao-yuan city. He is a music­lover, and also a veteran hi-fi fan.
Once he heard the sound from Audio
Valve in a music exhibition hall, and
since then he cannot tear himself
away from the sound and has
immersed himself into the business
world as an agency of Audio Valve. He

explains that T&V not only relates with

his work (audio and video), but also
stands for “Technology” and
“Vacation” which implies it “enables
you to enjoy the vacation via
technology”. Through this, we sense
his great passion for promoting music
appreciation. Since he is an exclusive

dealer for Audio Valve, of course he

has the greatly praised Assistent50
integrated amplifier. From appearance

and shape, these two products are
almost alike. But, Assistent 100 is of

much bigger volume and 20kg heavier
than the other. Assistent 50 can only
be started via remote control while
Assistent 100 has switches on the
panel. As one more special point to

mention, Helmut Becker designs two

small gauges on Assistent 100, which

adds perfect classical tone and also
funny experience when they light up
in case of big output power.
Assistent50 uses two QQE 03/12
power valves, while Assistent 100
employs four legendary 6C33 power
valves. How legendary? Let me tell
you.

Valves from a MIG Fighter

During the cold war between United
States and Soviet Union, in 1976, the
legendary pilot Victor Ivanovich
Belenko from Soviet Union drove a
MiG-25 Foxbat, the “top secret” at that
time, across the iron curtain and
landed in Japan. Certainly, Soviet
Union wanted Japan in any case to
return the fighter, but before giving it
back, US military experts had already
reached Japan and dismantled this
fighter. The experts gasped with

admiration at the technology and skill.
Moreover, they surprisingly discovered
on this MiG-25 the valves which were
quite obsolete at that time. Yes, exactly.
The valve always used on
communications equipments is 6C33.

It’s said this type of valve is designed
to resist the strong EMP produced
from nuclear explosion, since the
common crystal will lose function in
the event of EMP while 6C33 can
work normally. Besides, this type of
valve not only meets the high G
requirements of fighters, but also has
quite long service life. They can even
resist the nuclear explosion, not to
mention the electro-magnetic

interference in general environment.

In the acoustic application, what’s the
strength of 6C33 that makes DIY fans

so enthusiastic about it? It mainly lies
in its low internal resistance which
simplifies the manufacturing of output
transformer. Moreover, its plate current

is above 200mA and the peak value

even exceeds 1A, far higher than that
of the commonly used power valve.

What’s more, 6C33 can work under

rather low voltage (about
150V~200V), which also reduces the
requirements on all components
within inside. However, though 6C33 is
of good use, the circuit design is
rather difficult. The machine is likely to
get burned if not the design is not
careful enough. Certainly, with
appropriate design, the exquisite
sound will naturally come at your
fingers’ ends.

Complexity for Stability

What on earth did Helmut Becker

employ to handle this valve? The
answer is the exclusive ISBR
(Interactive Servo Bias Regulator).
To be exact, it’s the evolution version
of ABR (Auto Bias Regulator). The
four pieces of 6C33 used on Assistent
100 not only adopt auto bias, but also
each power valve is equipped with
auto-detection circuit. When the
valves are ageing or of malfunction,
the nearby LED lights will indicate the
state. Compared with the general valve

amplifier, though Assistent 100

produces high distortion at low input,

the distortion value remains almost
the same till whole output, unlike the
general valve amplifier which
produces higher distortion as the
output increases. So, at high output,

the distortion of Assistent 100 is

apparently much lower than the
general valve amplifiers. To respond to

the trend of environmental protection
and energy saving, AudioValve for the

first time applies Intelligent Power
Management on Assistent 100 to
control the electric current required by
the amplifying circuit, enabling the
optimal efficiency between the power
supply input and the power output
without influencing the sound
performance at all.

High heat has always been a fatal
weakness for 6C33 valve amplifiers.

Therefore, the valves are always
exposed for air cooling. But, Assistent
100 adopts a nearly closed box
structure, then how to resolve the
problem of heat dissipation? The fact
is that it’s quite easy by using the four
fans. Two of them are installed on the
left side of the box and started when
power on. The other two will work
synchronically only if high power, and
will stop when the gauge light is off.

You don’t need to worry about the
impact of fans on the sound quality at
all. We cannot hear any noise from the
fans even when we listen closely. It’s
evident that Audio Valve employs high-

class components.
The “cathode coupling output circuit”
always used by Audio Valve is also

applied on Assistent 100. Unlike the

general valve amplifiers whose power
valve plate is connected with the
output transformer, the output
transformer of Assistent 100 is
connected with the cathode of 6C33,
which results in the amplification
factor being 1. So, much higher
amplification should be added on the
front end to obtain sufficient gain. On

the front end of 6C33, AudioValve uses

two EF86, two CC82 and two QQE
03/12 for primary amplification, phase
splitting and driving. Though
complicated, this can be aimed to get
the most stable working state.

Fairly soft, beautiful and
comfortable

This time, we experienced on the site

Assistent 100, the “Top-level Special
Edition”. It’s specially designed for
Taiwan market. And the sales agency
particularly asks the factory to set the
acceptable input voltage range to ±
5%. If the voltage is out of this range,
Assistent 100 cannot be turned on. To

better enjoy the beautiful sound of

Assistent 100, we suggest you adjust

Audio Art Magazine

well the power supply beforehand. I

have already heard of the sound quality
of Audio Valve amplifiers, but this time

we used the valve amplifiers I’ve
never listened before. My first concern
is whether Assistent 100 still retains
the beautiful sound quality as
consistently produced by Audio
Valve? We played the third song
“Times of Your Life” in Joanna Wong‘s
new album “The Adult Storybook”.
Upon hearing her voice, at once I felt
quite relieved. The sound from
Assistent 100 is fairly soft, beautiful
and comfortable. It has all the flavor of
valve amplifiers, and, besides, has
very good resolution. The sound of

piano, guitar and string instruments feel
very exquisite and gentle. It is of high
fidelity and excellent resolution.
Moreover, the background is
exceptionally pure and clean. Joanna’s
voice has no much exaggeration, and
neutrally and directly passes to my ears.
You can even hear each tiny element in
the sound when she sings lightly,
without any careless feeling given by
common high power valve amplifiers.

Rich tone variety

Then, listen to the first song I Love You

Porgy in the “Joshua Bell at Home with

Friends”. The piano touch key at the
right start is quite clear and full, like a
real acoustic grand piano in front of my
eyes. Bell’s violin has a strong flavor of
wood, presenting a noble and dignified
taste. The trumpet played by Chris

Botti is quite smooth and tender, like
feeling the silky velvet. All these prove
that the sound quality presentation of
Assistent100 is of superior level.

Coming to the melodious violin playing
at the beginning of the second song, we
can sense that the rich overtone
structures and the end-rhyme is fairly
charming so that the sound even at the
high position is not irritating but naturally
extending upward. Through Assistant
100, the abundant tone variety created
by Bell is just like Leica camera
displaying rich tones and appears
versatile, with awesome beauty and
fidelity. When listening to this album, I
even particularly turn up the volume to
check whether Assistent 100 can really

maintain the low distortion even at
greater output. Amazingly, no matter

how big the volume is, I didn’t feel any
“noisy” sound or “dry” musical quality I
heard from other general amplifiers.
Instead, the whole listening experience
is quite smooth, full of sweet taste and
moisture, which is indeed rarely
amazing.

Low frequency of abundant
layering

In the new album promoted by RR,

Britten’s ORCHESTRA, the
performance of the orchestra presents a
very good sense of layering from near to
far, forming a fine musical picture woven
in silk. In fact, the low-frequency of

Assistent 100 is not too much, but it
has a perfect proportion with medium
and high frequency, with very good
layering. When the drum is being
beaten, the vibration of the drum head
can be heard quite clearly, with the
vibration wave lingering in the air. The
sound is cohesive without the
pressure feeling, which is the best
portrait of loose and comfortable
state. On the site, it works with the

highly efficient Dynavox GEM Opal

speaker (reviewed in the No. 160
publication), which better
demonstrates the loose and
comfortable feature of Assistent 100.

At the same time, the design of high
electrical current in Assistent 100 takes

under good control the 12-inch low
frequency woofer of GEM Opal. The
low frequency line ends very clean,
presenting an excellent transient state
between dynamic and static ones. In a

word, I think the sound of Assistent 100

is whole and comprehensive. It can
definitely pass the “Twenty Factors of
Stereo” with high scores.

Incomparable musicality

You may know the Buddhist word
“TiHuGuanDing (being enlightened)”,
but only few of you may know what
“TiHu” really refers to. Tihu is actually a
kind of finest cream repeatedly
extracted from the cow’s milk. As for me,
the sound quality of Assistent 100 is

the most wonderful “Tihu”, which, with
the balanced and exquisite overall
performance, makes the sound of
Assistent100 quite pleasant to hear,
even repeatedly. The stereo fans who

have listened to the high-power valve
amplifiers of AudiValve must know the
sound of such products is no never
coarse. It’s like a martial artist with deep
internal force, giving out exquisite sound
through a skillful way. It’s the same for
Assistant 100 using 6C33. Mr. Chen

from T&V told us he always got
indulged in listening to Assistent100 in
the audio-visual room for a whole
afternoon, forgetting the surrounding
world. Isn’t this the best evidence for
the incomparable musicality of
Assistant 100?

A