Hafler DH-110

David Hafler was an American Audio engineer who was best known for his work on improving the Williamson amplifier design through the use of ultra-linear circuitry. His background as a producer of linear power supplies for use in audio applications lead to the founding of Dynaco, and later, in 1972, to the founding of the David Hafler Company, a manufacturer of high quality audio products at affordable prices. Under the supervision of its founder, the company produced many famous preamps, among them the DH-101 and DH-110, as well as a line of MOSFET power amps, including the DH-120, DH-200, DH-220, DH-500, and XL-280.

The Hafler DH-110 was the company’s second preamplifier design. It replaced the DH-101 and was built from the early 1980s to the early 1990s. In typical Halfer fashion, the unit came in form of a DIY kit as well as in fully pre-assembled condition. The DH-110 has a sleek and unobtrusive design and is very well equipped. The features include a headphone amplifier, a muting circuit to prevent downstream thumps, a mono and tone control defeat switch, a rumble filter, as well as an external processing loop. The body is well constructed and protected from outer interference through full copper coating, similar to the Harman / Kardon designs of that time period. With two tape loops and two phono stages, the amplifier offers great connectivity.

While this is a great preamplifier for the price and can well keep up with mid-priced modern designs in terms of tonality, there is also some criticism. For example, the headphone stage is not very loud. Therefore, if your headphones need lots of clean power, this preamp might not be the right on for you. The volume attenuator steps are quite enormous, this especially becomes and issue when listening at night when the house is asleep and the steps at low volume leave you stranded between to quiet and too loud. Another issue is that only one of the two outputs is actually run though the volume attenuator, which does not make it a great companion when bi-amping your speakers or wanting to add a subwoofer – whoever would want to do such a thing. In combination with the Hafler DH-120 amplifier, the unit produces a decent and musical sound with lots of drive forward. It is not as delicate and refined as the Restek V1 or the DB Systems DB1 preamplifiers, but then these cost 3-5 times the amount of the Hafler, and many will wonder whether it is actually worth paying the extra.

Specifications

PHONO PREAMP SECTION

• Rated Output: 3 Wms, 8 Hz-105 kHz
• Maximum Output (3.5): 12 Vrms, 20 Hz-20 kHz
• Total Harmonic Distortion: Less than 0.0006% @ 1 kHz
• RIAA Equalization Accuracy: +0, -0.1 dB, 30 Hz-15 kHz
• Full Power Bandwidth: -6 dB, 4 Hz-210 kHz
• Sensitivity (3.7): 12.5 millivolts
• Signal to Noise: 87 dB
• Slew Rate: 12 volts per microsecond

LINE AMPLIFIER SECTION

• Rated Output: 3 Vrms, 4 Hz-210 kHz
• Maximum Output (3.5): 14 Vrms, 20 Hz-20 kHz
• Total Harmonic Distortion: <0.001%, 20 Hz-20 kHz
• Signal to Noise: 90 dB
• Slew Rate: 12 volts per microsecond
• Rise Time: 2.5 microseconds maximum
• Channel Separation: > 82 dB @ 1 kHz

GENERAL SPECIFICATIONS

• Inputs: 2 Phono, Tuner, Compact Disc or Video, 2 Tape recorders, EPL Outputs: 2 Tape (buffered), 2 Line, EPL, Headphone Jack
• Controls: Volume, Balance, Bass, Treble, Input Selector, Phono l/2 Selector,
• Monitor Selector, Mono-Stereo, Filter, External Processor Loop,
• Power Consumption: 3.5 watts
• Dimensions: 17” wide x 3” high x 81⁄2” deep
• Net Weight: 5 Kg.
• Country of manufacture: U.S.A.
• Year(s): 1982 - 1992

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