ALLNIC AUDIO H-5000, Руководство пользователя

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Why LCR?
There are four de-emphasis methods for equalization to that can be applied at playback:
A. Active filters (Negative feedback types):
Different quantities of negative feedback are applied, with deeper feedback to the high
frequencies and shallower to the low frequencies. The benefits of this method are improved
signal to noise ratios, low cost and consistent operation. Some of the shortfalls are looser bass
reproduction and, possibly, a pinched and compressed high frequency playback due to excess
feedback ratios.
B. Passive filters (CR type):
The frequencies are filtered to fit the RIAA specification by varying the amount of attenuation at
different frequencies through a complex capacitor-resistor network. This technique results in no
voltage overload, purer reproduction (because there is no feedback), and more accurate RIAA
compensation. However, there are problems because the system provides no gain, and insertion
loss and impedance matching issues arise.
C. Hybrid filters (use of both CR and negative feedback types):
In this method, both types of filters applied separately; an active filter is applied to the low
frequencies and a passive filter to the high frequencies. Unfortunately, both the advantages and
disadvantages of each of these two types
of filters, already discussed, affect the playback system at the same time.
D. LCR filters, used in the H-5000:
Two pieces of a linear reactor (a kind of choke coil) comprise the main part of these filters,
assisted by precise CR filters, in order to lower impedances and insertion loss.
In vacuum tube circuits, active and passive filters usually are operated on one hundred plus
kilo-ohms of impedance. An LCR equalization filter's impedance is a constant 600 ohms.
Furthermore, an LCR equalization filter's series resistance is less than 13 ohms (as a
comparative, some famous ones are 31 ohms). The lower the impedance, the more dynamic is
the sound reproduction, with better bass response and speed.
But LCR equalization units have drawbacks as well. These drawbacks are high cost and the
difficulty of impedance matching; the latter has been the primary hindrance to the
commercialization of this superb method in the construction of phono-stage amplifiers.
However, Allnic Audio manufactures high quality LCR equalization units in-house and has
developed a 600 ohms impedance matching method.