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发表于 2008-8-28 16:16:25
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Without doubt the SYMPHONY is the best headphone amplifier we ever made. Of course this amplifier also uses the concept of balanced ground. With this concept the headphone ground is not connected to the internal signal ground but carries a signal such that the sum of the potentials of the headphone connection wires equals zero. This strongly minimizes the energies stored and released in the electrical fields inside the headphone wire when an audio-signal is applied. The influence of the wire on the sound is thus reduced.
Moreover, with active ground polution of the internal signal ground by strong driving currents is eliminated and the power-supply-rejection-ratio at the output stages is strongly improved. Thus the best conditions are given for a clean and undistorted sound.
Balanced ground offers most of the advantages of a true balanced headphone setup without the need of balanced connections. It can be used with any conventional dynamic headphone.
The amplification section is build around LM6171 opamps biased into class-A. For the output stages BUF634 buffer amplifiers are used. These integrated circuits are very fast and thus allows the output signals to follow the input signals very closely. The amp is DC-coupled and any capacitors found in the signal path are of the highest quality polypropylen and polystyrol.
An extra feature of the SYMPHONY is a high quality built-in DAC. Digital data are accepted through optical or coaxial S/PDIF inputs or through the USB-port that can be easily connected to any computersystem. Never did your PC sound that good!
The digital receiver section is based on the DIR9001 receiver chip. Instead of the usual PPL-settings we implemented a mode of high jitter reduction. Digital input signals are decoupled using separate input trigger circuitry.
The DA-conversion section is based on the newest top-of-the-line Wolfson WM8741. This chip offers 9 different digital filter modes that can be selected by the user. Sound thus can be adapted to personal taste.
A very extensive powersupply, using three separate transformers and a large number of power-regulators assures the best working conditions for any part of the circuitry.
The amp is a true eye-catcher. Maybe not everybody likes its looks, but the anodized aluminium enclosure is far from the conventional box design that characterizes most other amps. The SYMPHONY has a face and a voice of its own!
Crossfeed
The extreme channel separation offered by headphones is artificial and not found in real nature. For many listeners this results in mental stress when using headphones.
It is impossible to think of a CORDA amplifier without crossfeed filter. A crossfeed filter simulaties aspects of the natural hearing process to reduce this stress and to make headphone listening more relaxing. For more information please press the button below.
For many people the filter is a must for relaxed listening without stress. For those who don't need it the filter can be simply switched off.
Variable output impedance
Normally a headphone amplifiers has a very low output impedance which gives the amp tight control over the headphone action. However, many headphones have been sonically optimized to be driven by an output impedance of 120 Ohm. This output impedance is an international standard.
The OPERA has two headphone-sockets, one with a very low output impedance and one with 120 Ohm output impedance. This allows to optimize the driving characteristics for the headphone used. On request the 120 Ohm output can be converted into an output with low output impedance.
Balanced ground
Each driver of a headphone is connected to the amplifier by two wires. Normally one of these wires (the ground wire) is connected to ground and thus carries a constant zero-Volts signal. The other wire carries a varying voltage, the electrical audio signal. The driver is driven by the voltage-difference between both wires.
The voltages of the 4 wires change continuously and the external electrical fields generated by the electrical charges on the wires change accordingly. There is energy associated with these fields and thus energy is constantly stored and released. The properties of the insulating material have a strong influence on this process and thus effect sound quality.
The SYMPHONY does not keep the signal of the ground wires fixed but adds an extra signal to all the four wires (signal wires and ground wires) such that the sum of the voltages of the 4 wires is constantly zero. This extra signal is the same for all wires so the voltage differences between the two wires of a single driver do not change. The effective audio signal is still the same.
However, since the sum of the voltages is zero, the total electrical charge on the wires is also zero. The external potential field is strongly reduced and much less energy is stored and released when an audio signal is applied. The purity of the sound signal is much less effected by the properties of the insulating material.
The pictures below show an example of a typical headphone cable driven by a conventional headphone amplifier (left picture) and by the SYMPHONY (right picture).
[ 本帖最后由 Pan 于 2008-8-28 16:25 编辑 ] |
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发表于 2008-8-28 16:16:14
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发表于 2008-8-28 16:17:43
