3
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Designing a clean, strong but balanced power supply for noise-free DHT phono amplification
Since DHT amplification is so sensitive, and has the potential for extremely low noise reproduction,
an all tube, high-speed, automatic voltage regulation (AVR) circuit is most appropriate for the power
supply. AVR enhances the signal to noise ratio for noise free operation in dual mono mode. For the
H-5000 phono-stage preamplifier, Allnic uses 300B tubes, a typical DHT, as a series regulator tube in
an AVR circuit. This design results in a
superior signal to noise ratio.
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INTRODUCING THE H-5000 PURE DHT PHONO-STAGE
The H-5000 is Allnic Audio’s top of the line phono-stage. Like all Allnic Audio products, it uses
Permalloy (iron and nickel alloy) for its signal 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.
Key Features of the H-5000 Phono-stage:
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LCR TYPE PRE-RIAA AND 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. Before the establishment of the RIAA equalization
standard, different production companies utilized different equalization curves.
Vinyl record production 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. In order 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, in order 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.
The H-5000 is equipped with newly developed Allnic “Multi-Curve” LCR units (one for each
channel) which have four (4) Turn-overs (frequency options) and four (4) Roll-offs (gain
reductions in dB). These new units provide for the reproduction of various recording curves
(both for bass attenuation and treble boost) used by different companies prior to the
establishment of the RIAA standard. There are 4 Turn-over options, at: 250Hz, 400Hz, 500Hz
RIAA and 700Hz. There are 4 Roll-off options (at 10KHz): -5dB, -11dB, -13.7dB RIAA and -16dB
(See Figure 7).
The rectifier tubes supplied with the H-5000 power supply are DHTs. Please note that in
some electrical environments, the rectifier tubes in the H-5000 power supply may need to
be changed to an indirect heated tube. While rectifiers can have audible effects, the
rectifiers are not in the signal path: the signal path in the phono-stage remains pure DHT.
Summary of Contents for H-5000
Page 1: ...ALLNIC AUDIO H 5000 DIRECT HEATED TRIODE PHONO PREAMPLIFIER OWNER S MANUAL ...
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