Description

Allnic Audio H-10000 OTL/OCL Phono Stage Preamplifier

The H-10000 OTL/OCL is the flagship phono-stage preamplifier from Allnic Audio, designed to deliver the highest level of analog playback performance. Built around an advanced output transformer-less and output capacitor-less circuit, the H-10000 represents a rare and highly sophisticated approach to tube phono amplification.

In most vacuum tube designs, transformers or capacitors are used at the output stage to couple the amplifier to the next component in the audio chain. While effective, these components can introduce coloration, signal loss, and additional distortion. The H-10000 removes both elements entirely from the signal path through its OTL/OCL architecture. By eliminating these coupling components, the circuit achieves a more direct connection between amplification stages, preserving the delicate musical information extracted from vinyl records.

Implementing an OTL/OCL circuit in a phono-stage is extremely challenging because phono cartridges produce extremely small signals that require significant amplification. Despite this complexity, the H-10000 successfully applies this architecture to achieve extraordinary clarity, dynamics, and tonal purity.

Design and Construction

The H-10000 consists of two separate chassis: a dedicated power supply unit and a main amplification unit. This dual-chassis configuration helps isolate sensitive audio circuitry from electrical noise generated by the power supply, ensuring a cleaner signal path and improved overall performance.

The front panel of the amplification unit provides intuitive control over the unit’s advanced functionality. A central rotary selector allows the user to switch between four different inputs. Below the selector are two pairs of equalization controls, one set for each channel, enabling precise adjustment of turnover and roll-off parameters for various phono equalization curves.

Four balance meters are positioned on the front panel, two per channel, allowing users to monitor whether DC is present during the amplification process. A mute/operate control is also provided to allow safe operation when changing inputs or making adjustments.

The rear panel offers flexible connectivity options. Four pairs of RCA inputs support two moving-coil cartridges and two moving-magnet cartridges. Both balanced XLR and unbalanced RCA outputs are available, allowing easy integration with a wide range of preamplifiers and high-end audio systems.

Vacuum Tube Amplification

The H-10000 employs a total of sixteen vacuum tubes arranged in a dual-mono configuration, with eight tubes dedicated to each channel. This arrangement allows the phono stage to achieve extremely high gain while maintaining exceptional channel separation and low distortion.

The amplification process occurs across two stages. In the first stage, the signal from the phono cartridge is amplified using an ECF802 triode-pentode tube. This is followed by an E180CC double triode and two 7233 triodes, which further increase gain and drive the signal toward the equalization network.

After the phono equalization stage, the signal passes through a second amplification stage that mirrors the same tube arrangement: an ECF802, an E180CC, and two 7233 tubes. This multi-stage configuration enables the H-10000 to deliver the very high gain levels required for phono amplification while maintaining stability and extremely low distortion.

The output stage uses a single-ended push-pull topology based on the 7233 tubes. These tubes were selected because of their unusually low internal resistance, approximately 230 ohms, which allows them to drive the following preamplifier or integrated amplifier with authority while maintaining a transparent signal path.

Silver Coil Moving Coil Step-Up Transformers

Another important feature of the H-10000 is its integrated moving-coil step-up transformers. These transformers are wound using pure silver wire rather than conventional copper conductors.

Silver provides superior electrical conductivity, which reduces coil resistance and improves signal transfer efficiency. Because moving-coil cartridges produce extremely small output signals, minimizing losses within the transformer is critical to preserving musical information.

Allnic’s step-up transformers are also built using high-permeability permalloy cores, a material known for its exceptional magnetic characteristics. This combination of permalloy core material and silver wiring results in transformers capable of extremely accurate signal transfer.

Each transformer provides four selectable gain levels, allowing the user to match the phono stage precisely to the characteristics of different moving-coil cartridges. Selecting a gain setting automatically adjusts the input impedance of the moving-coil input, ensuring proper electrical loading for optimal performance.

LCR Multi-Curve Equalization

The H-10000 incorporates dual mono LCR multi-curve equalization modules that allow the phono stage to reproduce not only the standard RIAA playback curve but also several historic equalization standards used on older vinyl recordings.

The LCR equalization method uses inductors, capacitors, and resistors arranged in a passive network. This approach is widely regarded as one of the most accurate and natural sounding methods of implementing phono equalization.

Using the front-panel controls, listeners can adjust the turnover frequency and high-frequency roll-off parameters independently for each channel. This allows the phono stage to reproduce recordings mastered using different equalization standards, including those used by early record labels before the adoption of the RIAA standard.

This flexibility makes the H-10000 particularly valuable for collectors of vintage vinyl recordings.

Performance and Engineering

The H-10000 is designed to deliver exceptional performance across all measurable parameters. The unit provides a frequency response from 20 Hz to 20 kHz with essentially flat RIAA accuracy.

Total harmonic distortion remains below 0.1 percent at a one-volt output level, ensuring clean signal reproduction even at high output levels. Signal-to-noise ratio is rated at approximately −80 dB, providing a quiet background that allows subtle musical detail to emerge clearly.

The output impedance is maintained at a constant 50 ohms, ensuring compatibility with a wide range of preamplifiers and line-level components.

Technical Specifications

Inputs

• Moving Coil (MC): 2 × pairs RCA inputs

• Moving Magnet (MM): 2 × pairs RCA inputs

• Built-in 4-step pure silver coil MC step-up transformers

Outputs

• 1 × pair RCA (unbalanced)

• 1 × pair XLR (balanced)

Ground

• 2 × screw-type grounding terminals

Equalization

• Dual mono LCR multi-curve equalization modules

• Supports RIAA and additional historical phono curves

Frequency Response (RIAA)

• 20 Hz – 20 kHz (±0 dB)

Voltage Gain

• MM: +40 dB

• MC: up to +72 dB depending on step-up transformer setting

Step-Up Transformer Gain Options

• 22 dB (×13)

• 26 dB (×20)

• 28 dB (×26)

• 32 dB (×40)

Input Impedance

• MC: up to 200 Ω

• MM: up to 47 kΩ

Maximum Input Voltage (MM)

• 30 Hz: 100 mV

• 100 Hz: 150 mV

• 1 kHz: 300 mV

• 10 kHz: 600 mV

Total Harmonic Distortion

• Less than 0.1% at 1 kHz (1 V output)

Output Impedance

• 50 Ω

Signal-to-Noise Ratio

• −80 dB (CCIR, 1 kHz)

Power Consumption

• 190 W

• 110 / 120 V or 220 V

• 50 / 60 Hz

Vacuum Tubes

• 4 × ECF802

• 4 × E180CC

• 8 × 7233

Dimensions

Phono Stage Unit

• 430 mm (W) × 380 mm (D) × 200 mm (H)

Power Supply Unit

• 430 mm (W) × 330 mm (D) × 130 mm (H)

Weight

Phono Stage Unit

• 12.6 kg unpacked

• 16 kg shipping weight

Power Supply Unit

• 16 kg unpacked

• 19 kg shipping weight

Source: https://allnicaudio.com/product/h-10000/