ALLNIC AUDIO L-8500 OTL/OCL, Руководство пользователя

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INTRODUCING THE L-8500 OTL/OCL LINE-STAGE PREAMPLIFIER
Immerse yourself in the original recorded space. The L-8500 OTL/OCL (Output Transformer-
Less/Output Capacitor-Less) is a triple gain stage, remote controlled, line-stage preamplifier,
without transformers or capacitors in its single-ended signal path. It uses the 12B4 triode as
its directly coupled output power tubes; i.e., there are no output transformers on the single-
ended (unbalanced) RCA outputs, so the 12B4s communicate the signal directly to the
connected power amplifier or amplifiers, fully revealing the 12B4s’ inherent accuracy and
beauty.
In common circuits, output capacitors or output transformers are required to separate the
AC music signal from the DC operating potential. If this is not done, the latter will destroy
the power amplifier, the loudspeakers, or both. However, these two coupling devices also
introduce their own influences on the transmission of the musical signal, adding their own
character (colouration), increasing distortion, and consuming small signals, all as predicted
by physical efficiency theory. In addition, they also limit signal dynamics. For these reasons,
the elimination of output transformers and capacitors has been considered the best solution
for the design of the most accurate amplifiers. Removal of these two coupling devices from
the signal path achieves the best results possible:
•
No colouration of the musical signal
•
Extremely detailed expression, natural harmonics and subtle musical decay
•
The lowest possible distortion
•
The widest musical dynamics
In the L-8500, there is no coupling device between the preamplifier and the power amplifier;
that is, the final gain/output tubes are directly connected to the power amplifier. Thus, the
benefits listed above are fully present in the Allnic L-8500 preamplifier.
Some circuit experts might be concerned about DC potential in the music signal in an
OTL/OCL design. However, the chance of this problem occurring can be essentially and
reliably 100% mitigated. To do this, Allnic uses a “floating power supply circuit”, a design
that deals with the issue by not creating any DC potential in the first place, or such a small
potential that it is harmless.
The L-8500’s OTL/OCL circuit is basically SEPP, “Single-Ended, Push-Pull”, so a “cancellation
circuit” is required to adjust the balance of signal between the upper and lower power
output tubes’ input grids. Allnic uses an extremely sophisticated “Active Balanced Positive
and Negative Feedback Circuit”, in which the 6AN8 pentode perfectly controls the circuit’s
operation with extremely low distortion and incredible speed.
The L-8500 OTL/OCL is a world-class, reference level, line-stage preamplifier. It offers
unbelievably realistic, holographic sound-staging combined with incredible resolution,
clarity, micro-dynamics, and drive. Instrument and vocal tones and timbres are