Hafler DH-110

Ten pounds of kit-built preamp that Hafler's own manual says "defies comparison, regardless of cost" - and the period reviewers largely agreed.

Overview

The DH-110 is a ten-pound preamp, 17 inches across, that shipped for $299.95 in kit form in 1982. It's a solid-state stereo preamplifier from David Hafler's company, sold as a build-it-yourself kit (DH-110K) and factory-assembled (DH-110A). The manual is plain about the design philosophy. The DH-110 is "the control center of your music system," the interface between sources and the power amplifier, and it should be "attractive and easy to use, versatile and yet functionally unobtrusive."

The record states one thing cleanly: the DH-110 was "in only the second generation of Hafler pre-amps," following the DH-101. Production years are murkier. One source says it sold between 1979 and 1983. Another lists it as a 1983-88 model. Given the 1982 review sample and the December 1986 classified ads still listing it, the later window looks more plausible, but the archive can't settle it. Treat any single-year claim with suspicion.

The most complete period record comes from HiFI-Stereo (August 1982, p.42). The reviewer measured the unit at 17 x 8' 1 x 3 inches and 10 pounds, priced the kit at $299.95, and found the specifications "exceptionally complete." Sensitivity was checked through both a high-level input (50 mV) and the phono input (1 mV) for a 0.5-volt reference output, and both came out "exactly as rated." The same review also took A-weighted output noise measurements, but the values aren't preserved in the surviving text.

The manual's claim that the DH-110 "defies comparison, regardless of cost" is the kind of line every manufacturer writes. The circuit description gives it some weight: a fully complementary symmetry push-pull topology, with a circuit-board layout explicitly designed to reduce crosstalk and preserve channel separation. It's the same approach Hafler used across the line.

Key Features

Two Phono Inputs and Bi-Directional Dubbing

The DH-110's rear apron carries two separate phono inputs for magnetic cartridges, plus two tape loops with bi-directional dubbing — meaning you can copy from deck A to deck B or the reverse without re-cabling. There's also a tuner input and an auxiliary stereo input, which the manual specifically flags as suitable for a compact disc player or video audio source. That last detail dates the design nicely: by the early 1980s, CD was arriving, and Hafler made room for it. An external processor loop lets you patch in a graphic equalizer, time-delay unit, or noise-reduction box without breaking the signal chain anywhere else.

Tone Controls That Get Out of the Way

The tone controls are switchable, and when they're switched out, they're isolated from the circuit entirely — the manual describes the bypassed response as "ruler-flat." This was a deliberate design decision, and it's the kind of thing that matters more than any single tone-control curve: you can contour the sound when you want to, and when you don't, the controls aren't quietly coloring everything you play. The manual also calls out tight-tolerance components for precise interchannel balance at all frequencies, and RIAA equalization engineered to narrow limits for consistent phase relationships and correct spatial perspective. Whether an owner hears that as "correct spatial perspective" or just "the records sound right" is beside the point — the design intent is documented.

Phono Loading You Can Actually Change

As shipped, the phono input presents 46.55 kΩ, close to the standard 47k. The manual also documents how to change it: swap R1 and R101 on the main board, and a table of 1% metal-film values gives you loads from 10 kΩ up to 35 kΩ. The manual publishes the loading math and recommends low-noise metal-film resistors. Hafler clearly expected owners to open the thing up.

Power Switching and Accessory Outlets

The rear panel carries switched and unswitched AC outlets. The manual notes the power switch has been tested to provide adequate capacity for any Hafler power amplifier and typical related equipment. The HiFI-Stereo review singled out the same surge-current capability, noting it was enough to drive Hafler's largest amp of the day, the DH-500. The power supply is regulated and tolerant. A unit wired for 120 V will run correctly anywhere from 95 to 130 volts, and the dual-tapped transformer can be re-strapped for 100, 120, 200, 220, or 240 V lines.

Kit or Factory-Built — and Rack-Ready Either Way

The DH-110 was sold both ways, and the manual treats the kit builder well. The board comes substantially pre-assembled and pre-tested, and the manual claims a novice can complete the build "in only one evening." The warranty is three years on a factory-assembled unit and one year on kit parts. The kit warranty is void if you used anything other than rosin-core solder. Acid-core or silver solder and paste flux get the unit returned unserviced. The unit also ships with accessory rack-mount end caps that extend the front panel to standard 19-inch width.

Historical Context

The DH-110 was Hafler's second-generation preamp, following the DH-101. The manual's phrase for it is a "versatile control center" with low noise and distortion. It was typically paired with Hafler power amps. The DH-220 and DH-200 show up alongside it in period discussion, and the review confirmed it could drive the DH-500, the biggest amp Hafler made at the time. The DH-330 tuner rounds out the family. The appeal was the same one Hafler sold across the range: high-technology hi-fi at a moderate price, with the option to save money by building it yourself. The kit-versus-wired price gap was substantial. One forum poster regrets having traded away a kit-built DH-110.

Collectibility & Value

Values are modest and steady. A tested-working DH-110 has been listed around $299. In December 1986, Audio (p.159) classifieds showed the DH-110K at $360 and the DH-110A at $440, so the used market has settled back to roughly the original kit price four decades on.

The bigger issue is age. These units are now well past forty years old, and the electrolytic capacitors are the usual suspects. Recapping is common practice among owners, with Panasonic FM and Nichicon Muse series frequently cited as replacements, and there's a well-known diyAudio refurbishment thread devoted to the model. A YouTube video from 2023 is titled around "fixing the most common issue," though the archive doesn't document the specific fault. Rack ears (Hafler 5327-651) turn up separately, often unused.

eBay Listings

See all Hafler DH-110 on eBay

As an eBay Partner, we earn from qualifying purchases. This helps support our independent vintage technology research.