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  • The HPA-10000 OTL/OCL is a world-class, reference level, headphone amplifier. 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 HPA-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 HPA-10000 OTL/OCL’s casework and connection options. The HPA-10000 OTL/OCL is truly a masterpiece of sophisticated, purist vacuum tube audio technology.


    ThHPA-10000 OTL/OCL has a voltaggain of +28dB, and a maximuoutput of 10 watts. It works best with headphones having an impedance fro15 t600 ohms.


    ThHPA-10000 OTL/OCL has the following features:

    ·           High-qualityNOS tubes

    ·           True OTL/OCL design

    ·           Pure Class A operation

    ·           Precision 61-step, single silver contact, constant impedance attenuator volume control, the same as Allnic’s top line-stage preamplifiers. The HPA-10000 has fixed impedance and no (± 0db) channel imbalance at any volume level.

    ·           As are all Allnic Audio products, the HPA-10000 is fully RoHS (EU Reduction of Hazardous Substances regulation) compliant in construction and materials.


    The HPA-10000 is a highly sophisticated but “purist” piece of audio technology. It is intended for experienced vacuum tube audio enthusiasts who understand and have the patience to appreciate the virtues of an innovative but “no bells and whistles” approach to circuit design and the superior sonic and “vintage” characteristics of New Old Stock (NOS) tubes - and who also value the exceptional private listening experience that the very highest quality headphones provide. The HPA-10000 is not a “plug, play and forget”, mass-market device aimed at headphone enthusiasts generally. Like all Allnic’s top-tier products, it is first and foremost a state-of-the-art example of “Tube Amp Done Right”. Proper care and attention, partnering with other equally high-quality equipment, and following the guidance provided in this manual will facilitate easy use and a listening experience of essentially unequalled quality for many, many years.

    HPA-10,000 OTL/OCL (Line-stage & Headphone Amplifier)

    • ThHPA-10000 is Allnic Audio’s Output Transformer-less (OTL) and Output Capacitor-less (OCL) stereheadphone amplifier. It utilizes a trubalanced Positive-Negative cancellation circuit, has twice the power of the previous HPA-5000 OTL/OCL headphone amplifier and has pre-out connections, so it can also serve as a superior Allnic line-stage preamp for most amplifiers.


      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 (coloration), 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 coloration of the musical signal

      • Extremely detailed expression, natural harmonics and subtle musical decay

      • The lowest possible distortion

      • The widest musical dynamics and frequency range


      In the HPA-10000 OTL/OCL, there is no coupling device between the amplifying tubes and the headphones (or power amplifier when used as a line-stage preamp); that is, the final gain/output tubes are directly connected to the headphone outputs. Thus, the benefits listed above are fully present in the Allnic HPA-10000 OTL/OCL.

      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 HPA-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 7258 pentode tube perfectly controls the circuit’s operation with extremely low distortion and incredible speed.

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