L-10000 OTL/OCL Preamplifier

The L-10000 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 300B direct-heated, single-ended triode as its directly coupled output power tubes; i.e., there are no output transformers on the single-ended (unbalanced) outputs, so the 300Bs communicate the signal directly to the connected power amplifier or amplifiers. The 300B has justly won the reputation of being a superb output tube in single-ended amplifiers, and in the L-10000 OTL/OCL preamplifier they fully reveal their 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-10000, 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-10000 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 100% reliably eliminated by doing away with the potential for DC in the signal path. To do this, Allnic uses a “floating power supply circuit”, a design which deals with the theoretical issue by simply not creating any DC potential in the first place.

The L-10000’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.

In addition, Allnic’s newly developed 61 STEP CONSTANT IMPEDANCE BRIDGED TYPE ATTENUATOR, a world premiere, is standard with the L-10000 and enhances its lifelike, dimensional sound.

The L-10000 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 breathtakingly lifelike, and the placement of instruments and bodies in three dimensions startling, life-size, and addictive. The L-10000 OTL/OCL has no voice of its own, none. It is silent, except for the music emanating from the blackest of backgrounds. In addition, the stunningly realistic sonic quality is matched by the simple elegance, flexibility, and ergonomic functionality of the L-10000’s casework and connection options. The L-10000 is truly a masterpiece and is Allnic Audio’s top line-stage preamplifier. Few preamplifiers can compete.