High-Power Headphone Amplifier A High-End Headphone Amplifier Designed Around Drive Capability Allnic answers the most fundamental question in headphone amplifier design: “Not how much output power is required, but how precisely the load is controlled.” The ASRA / RHPA-7500 is a high-end headphone amplifier that addresses this question head-on, redefining the essence of true drive-oriented design. The RHPA-7500 moves beyond the conventional low-power assumptions of traditional headphone amplifiers. It is a drive-centric headphone amplifier engineered according to the same principles of current delivery, load control, and output structure used in speaker amplifiers. 1. Pentode · Triode Dual Output Architecture The ASRA / RHPA-7500 adopts a dual output architecture, delivering 20W in Pentode mode and 10W in Triode mode. In Pentode mode, the sound emphasizes energy, scale, and authoritative control. In Triode mode, density, purity, and the refined tonal character unique to vacuum tubes come to the forefront. Rather than focusing on output figures alone, the core design philosophy of the RHPA-7500 lies in allowing the listener to select the most appropriate drive mode to match the music and the headphones. 2. Permalloy Output Transformer (Permalloy Output Transformer) The output stage employs high-purity, nickel-based Permalloy output transformers. With its exceptionally high magnetic permeability and superior micro-signal responsiveness, Permalloy minimizes coloration and transient delay that commonly occur in conventional output transformers. As a result, the RHPA-7500 achieves an openness and speed reminiscent of OTL designs, while simultaneously preserving the distinctive texture and tonal richness of vacuum tubes—despite utilizing a transformer-coupled output stage. 3. Dedicated Output for RAAL Ribbon Headphones Ribbon headphones inherently require dedicated impedance matching and output design. Rather than treating RAAL ribbon headphones as an exceptional or problematic load, the ASRA / RHPA-7500 formally integrates a dedicated drive circuit, including a dedicated Permalloy output transformer, specifically engineered for RAAL ribbon headphones. This design allows ribbon headphones to be driven directly and stably without any external interface, delivering fast, transparent high frequencies and outstanding spatial resolution. 4. Versatility Beyond a Headphone Amplifier In addition to 1/4-inch and 4-pin XLR headphone outputs, the RHPA-7500 is equipped with speaker binding posts, enabling it to directly drive small, high-efficiency speakers. This amplifier transcends the traditional boundaries between a headphone amplifier and an integrated amplifier, offering an expanded playback platform. 5. Precision Volume Control (41-Step Constant Impedance Attenuator Option) The optional 41-step Constant Impedance Attenuator maintains consistent channel balance and tonal density regardless of volume level. Even during fine volume adjustments, it provides precise control without compromising the sonic character. S PE CI F I C A T I O N S F O R: Vacuum Tubes ECF80 × 2 / 12AU7 (6211) × 2 / 7558 × 4 Output Power 20W (Pentode) / 10W (Triode) Output Impedance 10Ω – 300Ω Voltage Gain +28dB Headphone Outputs 1/4″ (6.35mm) × 1 4-pin XLR × 1 RAAL Ribbon Dedicated 4-pin XLR Speaker Output 1 Pair Binding Posts Analog Inputs RCA × 3 / XLR × 1 Volume Control Precision Potentiometer (Option: 41-Step Constant Impedance Attenuator) Frequency Response 20Hz – 20kHz (±0dB) Dimensions (W × D × H) 35.5 × 44.5 × 14.0 cm Weight 12 kg
