Manufactured In Germany
NEW - V800 Digital Audio Converter
Inputs: Balanced - Coax - Toslink
V200 Headphone Amplifier DAC
Inputs: RCA - XLR Balanced - USB
V181 Balanced Headphone Amplifier DAC
Inputs: RCA - XLR Balanced - USB
V100 Headphone Amplifier DAC
Inputs: RCA - XLR Balanced
V90 Headphone Amplifier
Violectric Technology Exlpained
Which advantages do balanced signals
In contrast to unbalanced signals, balanced signals are carried by two wires
(plus ground/shield). In the transmitting device, a balanced signal is created by
generating an inverted original signal (180 degrees phase shifted). The "hot"
wire carries the original signal (a), the "cold" wire the inverted signal
(-a). In the receiving device, the balanced signal is processed by a differential
amplifier, which detects the difference between both: (a) - (-a) = 2a.
On its way between devices, the useful signal can be affected by interference (s).
Interferences however are in phase on both wires and fed to the differential amplifier
as well. Again, the amplifier detects the difference between the interference contents:
(s) - (s) = 0. Thus - in an ideal situation - all interference on the signal
path is eliminated.
Why are discrete signal paths important?
Twin op-amps are the most common design for operational amplifiers, i.e. two amplifier
circuits are integrated in one device. If left- and right-channel signals are processed
simultaneously by such a device, interaction between both cannot be excluded. This
interaction is admittedly diminutive, but should be avoided whenever a different
design offers the possibility.
Why are op-amps ideal for low-level
Discrete amplifiers (designed with transistors) are very popular in High-End
audio design also for preamplifier stages. This is often marketed as an optimization
measure, but the partially exorbitant extra expenses are of course to be paid by
the customer. But an op-amp consists of tranistors as well...
Moreover, its structure has the advantage of thermal coupling between its internal
components. Also ageing issues play a much less important role. Due to the large
number of op-amps types offered, it is possible to pick an optimum type for any
Why does an active feed-through make
Each electronic device presents input impedance as well as input capacitance.
If several devices would be coupled passively - e.g. with "Y" adapters
- the resulting input parameters could provoke malfunction and instabilities. A
buffer amplifier "reconditions" the signal and makes it compatible with
other devices due to its low-impedance output.
Why does PRE-GAIN make sense?
Two extreme examples (with the headphone amplifier at 8dB (x 2.5) overall
gain, volume control set to full):
The (pre-)amplifier provides 4V output voltage, whereas the headphone requires only
2V for 100dB sound pressure level. With the control fully turned up, the amplifier
would deliver 10V output at 8dB gain. Therefore the volume control would have to
be operated very carefully in order to avoid hearing damage. Moreover, any interference
at the input should be avoided since it would be "unforgivingly" amplified
as well. With PRE-GAIN, the input level can be reduced by 12dB (a fourth), with
1V instead of 4V as the result. This 1V is again amplified by 2.5 (8 dB), then equalling
2.5V. Now the volume control can be turned over almost the entire range.
The (pre-)amplifier provides 1V, whereas the headphone requires 20V to release 100dB
of sound pressure. With the volume control fully clockwise, the V200 would provide
2.5V at 8dB gain only - much to low for the headphone. By means of PRE-GAIN, input
level can be boosted by 12dB (four times), resulting in effective 4V. These are
again multiplied by 2.5 (8 dB), now equalling 10V. This is still not enough, but
far closer to the optimum value: The headphone achieves 114dB sound pressure level.
Why does frequency bandwidth limiting
In signal processing, sound is represented by AC voltages. Sound is audible
- for young people - from about 20 to 20000 Hz. The elder the listener, the less
he will hear high frequencies in particular. In order to transmit these frequencies
at optimum quality, the frequency response of an amplifier should be as wide and
as "flat" as possible. At the low end of the scale, this limit is represented
by DC, as there is no frequency lower than zero. In upward direction, the limit
can be set to practically any frequency, but the higher, the more susceptible the
device becomes concerning electro-magnetic interference. This is not audible in
the first place, but may interfere with the useful signal and then become evident.
Therefore, unrestricted frequency response attests thoughtlessness rather than remarkable
Why is a good volume pot essential?
A volume potentiometer is a mechanical control element, which can be obtained
on the market at any low price. Meanwhile it is often replaced by electronic circuitry,
exhibiting essential disadvantages concerning dynamic range, noise and distortion.
Conductive-plastic resistive tracks, high-quality multitap wipers and separated
chambers for the individual sections are highly desirable for sophisticated applications,
and high quality is inevitable to ensure trouble-free operation for years. Since
the market for really good pots is a small one, manufacturers like Noble or Panasonic
don't offer these any more. A current sample of top of the line pots is the
RK27 by ALPS, which is used inside HPA 100 and HPA V200.
Why are high supply voltages essential?
A headphone doesn't really require high power, but from the equation
P = U2 / R we can see that the square of the supply voltage determines the power
into a given load resistance. The higher the headphone's impedance, the more
voltage will be needed. But this deals with the achievable loudness to a limited
extent only: Technically spoken, music lives on fast transients which put high demands
on signal processing. And thus a fast transient can easily push an average amplifier
with +/-15 volts supply to its limits. Due to VIOLECTRIC´s high supply voltage you
will benefit from doubled output swing capability.
Why is a high damping factor essential?
When actuated, electro-dynamic systems respond with a counterforce. When
the voice coil of a headphone has been displaced by the signal, an (error)-current
will be induced when it swings back to its initial position. This current must be
suppressed as far as possible, which is effected best if the amplifier's output
impedance is the lowest possible. The damping factor describes nothing but the ratio
between output impedance of an amplifier and a given load. Since there is no known
technical specifications, we define the load (voice coil impedance) as 50 ohms.
This results in an output impedance of <0.06 ohms in case of the HPA V200.
Why does a relay make sense when switching
Amplifiers generate unwanted output signals when applying or removing power,
which can damage the connected headphones. The relay breaks the connection between
amplifier and headphone and thus protects the latter until electrical conditions
Why have we made such a huge effort?
A headphone amplifier is a device designed to condition audio signals with
regard to the very specific requirements of headphones. This doesn't sound too
spectacular at the first glance and can be achieved relatively easily. As with many
things however, the devil is in the details and much more effort is required to
design one amplifier for (nearly) all current headphone models. Headphones per se
are quite diverse, and there are two essential parameters: impedance and sensitivity.
In general, headphones with higher impedance can be regarded as less sensitive than
headphones with low impedance (which is not generally true, but in the majority
of cases). The sensitivity of headphones is usually stated in dB (sound pressure
level) per Milliwatt.
Extremes in this sense are the AKG K1000 with 74dB/mW on the one hand, and the Sennheiser
HD25 with108 dB/mW on the other hand: The K1000 requires 2500 times the power to
achieve the same sound pressure as the HD25.
There is also the fact that headphones with high impedance usually require much
higher voltage to achieve high loudness. Thus the amplifier must be designed with
high internal supply voltages.
Which USB devices can be connected
to the HPA V200?
Since the HPA V200 is a terminal device after USB regulations, it has a type-B
interface. Connections can only be established to hosts (tabletop or laptop PCs).
MP3 players or similar gear cannot be connected digitally via USB. Of coarse you
may connect these devices in the analog domain.
What about the quality of the USB
No matter if it's encoded MP3, CD audio or other audio files played back
from the host, the USB input is operated at 16 bit and (usually) 44.1kHz sample
rate. The USB receiver forwards the data to a D/A converter offering 105dB dynamic
range and �95dB THD+N. With these parameters, the achievable quality conforms the
16-bit CD standard, but is somewhat worse than the overall analog performance of
the HPA V200.
Why does 100% host volume setting
Volume control within the host is always accomplished digitally, i.e. bits
are removed from the data stream. Therefore a signal attenuated by 12dB has only
12 active bits left and distortion increases to 0,4 %.
Can the USB signal be utilized any
When the unbalanced cinch sockets of the HPA V200 are configured as outputs,
the converted USB signal is available there in analog form and can be used to feed
further external audio devices, like amplifiers e.g.
What the Experts Are Saying About Violectric
November 2009: Test in
Hifi Statement (click to read full review)
"Dr. Reinhold Martin who was in charge for testing was so impressed
about HPA V200 that he ordered one piece of HPA V200 afterwards to serve as his
personal reference unit!"
November 2009: Comparative Test in
Professional Audio Musik & Equipment
"All three Violectric headphone amplifiers are real top devices
which provide together with high quality headphones a real treat for the ears. Who
would want it absolutely honest and neutral is best suited with the V100. Who requires
even more detailed sound and an impulse behaviour hardly more to be excelled, has
to take V200 into account. In every aspect this is the best headphone amplifier
we have ever tested."
November 2009: Test in STUDIO Magazine
"My hearing test proved in practically every discipline clear advantages
for the Violectric HPA V200. It showed very exactly illustrated transients, delivered
clean impulses in the area of low frequencies and was convincing with much finer
details and an outlined, defined bass reproduction. My other amplifiers pointed
out blurred transients which tended to be pulled wide in the time domain and decreased
impulses discernible without strain, also with deep frequency which sounded rather
spongy. In the same manner a clearly better localisation on the stereobase, a more
differentiated picture of the acoustical rooms and progressive depth rates revealed
from the V200. To say it with a sentence, the V200 simply sounded classes better
(compared to the headphone outputs of a CD player and the Benchmark DAC), comprehensible
under any circustances with both headphones (Beyerdynamic DT880 / Ultrasone edition
8). I had the impression to put on a better headphone together with the Violectric