ALLNIC AUDIO H-6500 Owner's Manual - Page 4

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INTRODUCING THE H-6500 PHONO-STAGE

The H-6500 is Allnic Audio's mid-line phono-stage model, above the H-5500 and below

the H-7000 and the top-of-the-line H-8000 DHT. Like all Allnic Audio products, it uses

Permalloy (iron and nickel alloy) for its transformer cores. Allnic is grateful to Mr. G.W.

Elmen of Western Electric for inventing Permalloy for transformer core use, and in so

doing, providing an enormous service to recorded music listeners everywhere.

The H-6500 has the following features:

• LCR TYPE RIAA EQUALIZATION:

RIAA equalization is a specification for the correct playback of vinyl records, established

by the Recording Industry Association of America. The purpose of the equalization is to

permit longer playback times and improve sound quality.

RIAA equalization is a form of establishing a flat frequency response for the playback of

recorded music. The necessity for this equalization process arises from mechanical

difficulties inherent in record production. To prevent the cutting needle from over-

cutting into the next record groove in the bass, as a record is cut, some bass frequencies

are attenuated. In the treble region, for high frequency sounds not to be masked by the

noise inherent in moving a stylus over and through a modulated vinyl surface, some

treble frequencies are boosted. With the application of the correct filtering techniques

on playback, the result is a flat frequency response with better signal to noise ratios.

There are four de-emphasis methods that can be applied at playback:

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.

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.