Neurochrome TCA HPA-1

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Headphone amplifier

The Tom Christiansen Audio HPA-1 is an exceptional headphone amplifier for the most demanding audiophiles and audio engineers. Its high power, ultra-low distortion and particularly wide dynamic range make it one of the most accurate headphone amps ever measured.

The HPA-1 is completely transparent. It has no sonic signature and delivers precise, fatigue-free music reproduction.

Audio Science Review's verdict

"The Tom Christiansen Audio HPA-1 provides superb measured performance. It has no weaknesses, subjectively or objectively. It is completely transparent and as such joins the very exclusive club of half a dozen headphone amplifiers with such remarkable performance. Its price is high, though, just behind the Benchmark HPA4. It is up to you to decide whether the look and ergonomics of the unit, along with the brand's excellent support, justify the extra cost." Full review available here.

Design

The signal path stays balanced up to the volume control, an ALPS RK271 "Blue Velvet" potentiometer. The output stage is built around a fast, high-current current-feedback op-amp, error-corrected by a precision op-amp in a composite configuration. Susumu ±0.1% resistors at critical nodes, two Nichicon MUSE bipolar capacitors as the only capacitors in the signal path, and a 4-layer PCB. A protection circuit shuts the output down if excessive DC appears, protecting the headphones in the event of a failure.

In use

On the front panel: XLR or RCA input selector, 0 dB or +12 dB gain switch, volume and a 6.35 mm jack output. With 1.2 W into 32 Ω and an output impedance of 35 mΩ, it drives low-impedance headphones as well as 300 Ω models. The built-in switch-mode power supply accepts any mains voltage. Made in Canada.

Specifications

• Output power: 1.5 W into 20 Ω; 1.2 W into 32 Ω; 250 mW into 300 Ω
• THD: < -130 dB (300 Ω, 100 mW, 1 kHz)
• THD+N: 0.0003% (-110 dB) (300 Ω, 100 mW, 1 kHz)
• IMD SMPTE: < -108 dB; IMD DFD: < -112 dB
• Dynamic range (AES17): 130 dB
• Signal-to-noise ratio: 132 dB
• Residual noise: 1.25 µV RMS, A-weighted
• Gain: 0 dB or +12 dB
• Input sensitivity: 2.8 V / 0.7 V RMS (low / high gain, 32 Ω, 200 mW)
• Output impedance: 35 mΩ at 1 kHz
• Channel separation: 98 dB at 1 kHz
• Slew rate: ±17 V/µs
• Inputs: balanced XLR, unbalanced RCA
• Output: 6.35 mm jack
• Volume: ALPS RK271 "Blue Velvet" potentiometer
• Mains: 80–264 V AC, 47–440 Hz
• Dimensions (W × H × D): 140 × 55 × 210 mm
• Weight: 850 g