德国MEIER AUDIO CORDA CONCERTO耳放
CORDA CONCERTO
Take the design of the SYMPHONY, remove the DAC section, add a few small improvements to the amplification circuitry and exchange the luxurious enclosure for a more modest and plain version and what you get is the CONCERTO.
Of course this amplifier also uses the concept of active balanced headphone ground. Within this concept each headphone connection wire carries an additional signal such that the sum of the potentials of the wires equals zero. This strongly minimizes the energies stored and released in the electrical fields inside the headphone cable when an audio-signal is applied. The influence of the wire on the sound is thus reduced.
Moreover, with active ground pollution 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.
Active balanced headphone 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 volume control is technically very sophisticated. The position of the potentiometer is measured with the use of an AD-converter. The output of this converter is then used to switch a bank of relais to set the proper volume level. There are a total of 64 levels which allows for very small stepsizes and a very analog feeling. The advantages of this concept are strongly reduced channel-imbalances and a much cleaner and more detailed sound. The use of a conventional stereo-potentiometer does add its own sonic signature which is now prevented.
The amplification section is build around AD797 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.
A very extensive powersupply, a large number of power-regulators, and a total filter capacity of 85.000 microF (!!) assure the best working conditions for any part of the circuitry.
Of course this amp also has our proprietary crossfeed filter incorporated which helps to strongly reduce listening fatigue.
Technically the CONCERTO is an extremely advanced headphone amplifier and offers excellent value-for-money!
Active balanced headphone 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 CONCERTO 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 CONCERTO (right picture).
At the left below we see the signals as generated by a conventional headphone amplifier. The ground signal is kept constant. Left and right channel signals vary independently.
At the right we can see the signals generated by the CONCERTO. The ground wire now carries a signal that is also added to the left and right channel signals. The difference between Left and Ground and between Right and Ground is the same as in the left picture.
The left picture below shows the electrical potential field of the positively charged headphone cable when both signal wires carry a positive signal at the point of time indicated by the yellow bar at the picture above.
The right picture shows the potential field for balanced ground operation. It can be easily seen that field potentials are much lower than at the left picture.
The differences are even more pronounced in the far field, as shown in the next pictures. Since the "balanced" headphone cable has zero netto charge there is hardly any energy stored in the far field.
Apart from these principle benefits there are also some technical advantages offered by active balanced headphone ground.
When a positive signal is applied to a headphone driver by a conventional headphone amplifier current passes from the output stage of the amp, through the headphone driver towards the ground plane of the amp. During this process the current is "taken" from the positive power supply line whose voltage, as a result, will not be entirely constant. (In the pictures below the positive and negative supply lines are depicted as two large storage capacitors.)
The currents that run through the ground plane do induce small voltage differences. Ground is thus polluted and since it acts as a internal reference for all signal amplification processes sound quality is impaired.
Also variations of the powersupply lines are not entirely rejected/neglected by the output stage and are partly transferred to the output signal. This reduces sound quality even further.
When a signal is applied by the CONCERTO, current passes the signal output stage, the driver, and the ground output stage. Both positive and negative powersupply lines are "loaded" simultaneously. No driving currents pass through the internal ground plane. There is no pollution of the internal referfence.
The voltage variations of the two powerlines are mirrored. Their mean value is roughly constant. This strongly increases their rejection at the output stages.
If voltage variations are found in one of the powerlines only, then these have a similar effect on the signals of both the signal output stage and of the ground output stage. However, it is the difference between the two output signals that drives the headphone. This difference is not changed and the effective audio signal is not influenced. PSRR (Power Supply Rejection Ratio) is very high.
Balanced ground thus offers many advantages for a faithfull reproduction of your favourite music. It certainly makes the CONCERTO to one of the best amplifiers currently available.
德国MEIER AUDIO CORDA CONCERTO耳放
Technical detailsOutput impedance < 0,1 ohm
Maximum output 13V / 500 mA.
Discrete volume control. Typical stepsize 0.5 dB, 63 steps.
Gain switch. Maximum gain factors -6 / +7 dB
(or -12 / +7 dB user-selectable)
Crossfeed filter switch:
1. Stereo / crossfeed OFF
2. Crossfeed ON
1 pair of analog inputs
Input impedance 14 kOhm
Gold-plated input jacks.
Silver plated headphone jack (Neutrik).
Silver plated heavy duty switches
25 Watts toroidal transformer.
110V and 220V mains power switchable.
Power uptake 10 Watts
Built-in groundloop breaker.
Double regulated voltage lines.
Low impedance electrolytic buffer capacitors (Nichicon). Total Buffer capacity 85.000 uF.
Bypass capacitors in the power supply.
Polystyrol and polypropylen capacitors in the signal path.
Metalfilm resistors in the signal path.
AD797 opamps biased into class-A.
2 BURR-BROWN BUF634 buffer amplifiers at left and right headphone output channel.
(Active) balanced headphone ground.
Star-grounding and ultra short signal paths.
Signal paths and signal path components at the bottom side of the PCB for maximal shielding.
Sturdy anodized aluminium enclosure
Weight: 1.7 kg
Size: 24.5 x 17.7 x 6.7 cm 您也得翻译翻译才能显得您更专业，更权威不是么~~~
您这弄得有点应付了。。。 能否PM下价格
谢谢~~ 老板能否pm价格？谢谢 顶起来大家看看 看不懂 耳放？ 解码器? 引用第7楼ldjizhou于2010-08-14 11:12发表的 :
看不懂 耳放？ 解码器?
专业纯耳放 楼主写的是德文吗？米国人看不懂德文，麻烦给翻译翻译 价格多少啊 引用第11楼zhpmx500于2010-09-14 12:38发表的 :
价格多少啊
6880 既然价格都这么贵了，要是都翻译都搞不好，也拿来卖就显得不厚道了。
看外观，估计里面是和SOLO一个类型吧，还期待解剖图 里面比SOLO多得多 引用第9楼signalww于2010-08-16 20:24发表的 :
楼主写的是德文吗？米国人看不懂德文，麻烦给翻译翻译
明显是英文..... 这个不是700多美金包国际寄费吗？而且好像已经停产了。新的
叫classic 能不能翻译一下啊，这里能看懂的人不多的
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