Усилители для наушников — Zaehl H1

The H1 is a desktop headphone amplifier from Zähl Elektronik-Tontechnik of Bergisch Gladbach, Germany, designed and built by Michael Zähl, whose mixing desks are used by artists such as The Chemical Brothers, Nils Frahm and Aphex Twin. It uses the same amplifier circuitry as the larger HM1 headphone mixing amplifier, but drops the mixing inputs, the high and low equaliser, the A/B comparison and the preamplifier function for a shorter signal path. The HM1 is limited to 50 units a year, while the H1 has no production limit. The recommended retail price is EUR 6,500 excluding VAT, and the US price is USD 7,999.

Key specs that matter

Rated output is 4 W RMS into 30 ohm and 7 W RMS into 15 ohm, with peak figures of 7.6 W into 30 ohm, 11 W into 15 ohm and 12 W into 10 ohm, plus 18 W for 1.5 ms. Maximum output level is +23 dBu, and the output is limited by voltage at 10.6 Vrms rather than by current. Output impedance is 0.8 ohm in Class A mode and 0.045 ohm in Class A and Servo mode, where THD falls from 0.07 % to 0.0005 %. Frequency response is 10 Hz to 30 kHz within 0.05 dB, and 1 Hz to 500 kHz better than -3 dB at the headphone output. Noise floor is -101.5 dBu with volume at maximum and gain at 0, and line input impedance is 20 kohm. The chassis measures 195 x 90 x 300 mm and weighs about 4.5 kg.

Engineering and use context

The H1 is a pure Class A design with no switching parts, built dual mono with separate supplies per channel from an internal toroidal transformer shielded in mumetal, so no external power brick is needed. A front toggle chooses between Class A, which runs without negative feedback, and Class A with Servo, which adds feedback for lower distortion and output impedance. Because the output stage runs at full bias all the time, the amplifier draws around 43 W typical from the mains and needs free air around it for cooling. The stereo base control uses mid and side processing, with two steps wider, two steps narrower and a mono setting, while a 21 detent potentiometer sets balance. Relays cut the input when the volume is turned to minimum. Mains voltage is switchable between 230 V and 115 V.

Pairing

Outputs are a 4 pin XLR, a 6.3 mm jack and a 4.4 mm Pentaconn socket, fed from balanced or unbalanced line inputs, so a DAC with XLR outputs suits it best. A -10 dB gain setting with a lower noise floor makes the H1 usable with very sensitive in-ear monitors, while the voltage reserve covers low-efficiency planar headphones.

Alternatives

The Zähl HM1 adds mixable inputs, A/B comparison and a high and low frequency equaliser to the same amplifier circuitry.