ALLNIC AUDIO HA-5000 Benutzerhandbuch - Seite 4
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INTRODUCING THE HA-5000 PHONO HEAD AMPLIFIER
The HA-5000 is Allnic Audio's phono pre-preamplifier, or "Head Amplifier". It is an active,
tube based device for amplification of low voltage signals from moving coil cartridges to
allow connection of moving coil cartridges to the moving magnet inputs of a phono-stage,
such as the Allnic H-1202, H-1500 Plus, H-7000/V and H-8000 DHT. The HA-5000 is an active
phono pre-preamplifier, not a "step-up transformer" like Allnic's AUT-2000, which uses a
transformer to boost the signal from the cartridge.
The HA-5000 has the following features.
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Innovative Fixed Bias Circuit
In the HA-5000, two Nuvistor 7895 tubes, the smallest vacuum tube, perform as amplifying
devices. They magnify the tiniest signal in audio, the output voltage of MC cartridges, to match
to the MM input of phono stages. Allnic applies its innovative, fixed bias circuit to achieve quiet
and stable operation of the extremely sensitive 7895 tubes. The fixed bias circuit eliminates the
sub-sonics so harmful to phono stages and inherent in the characteristics of the R.I.A.A curve,
which requires amplification of the lower frequencies. The fixed bias circuit applies a sustained
negative DC voltage to the grid of the tubes and to the input coupling capacitors, blocking
capacitor "crossover distortion". This distortion is a common phenomenon but, unfortunately, is
often neglected in pre-preamplifiers. The result of no "zero crossover distortion" is, simply,
clearer and more vivid reproduction of the music.
Very High S/N Ratio
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The above mentioned characteristics of the R.I.A.A curve demand a hum-free pre-
preamplifier and, therefore, a silent power supply circuit. Even one micro volt (1/1,000,000 of
one volt) of hum noise (120Hz hum) in the output signal of a phono pre-preamplifier will
result 63mV to the loud speakers. That is unacceptable, and Allnic has overcome the issue
through its automatic pure vacuum tube voltage regulation circuitry. This voltage regulation
circuit minimizes power supply hum noise to inaudibility.
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Extremely Wide Frequency Range
Though the HA-5000 has a single gain stage and no negative feedback, its frequency range
capability extends from 15Hz to 125Khz(-3dB), revealing the full richness of the musical
information on vinyl.
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Ultra Flexibility
The capability to follow an unpredictable musical signal with ease is strongly believed to be
the heart of musicality for audio equipment. This ability can be indicated by square wave
response at high frequencies, especially at 10Kh and the even more rarely achieved 20Khz.
Exceeding these expectations, Allnic's HA-5000 shows a response shape that is, even at
100Khz, in a word, beautiful.
Micro-Phonic Free Tube Damping Know-how
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