Hafler DH-330 (circa 1984–1986)

The Hafler DH-330 is an FM tuner from David Hafler's company, sold in the mid-1980s as both a kit and a factory-wired unit. HiFI-Stereo (May 1984, p.36) listed it at $374.95 in kit form and $449.95 wired. On a factory-wired sample, the magazine measured 10.8 dBf (about 1.9 µV) mono usable sensitivity, slightly better than Hafler's own 11.3 dBf rating. The manufacturer's specifications also gave 50-dB quieting sensitivity of 17.2 dBf mono / 37.2 dBf stereo, THD of 0.1% mono / 0.18% stereo at 1 kHz, S/N of 72 dB mono / 68 dB stereo, and a capture ratio of 1.5 dB.

Audio's November 1986 equipment profile (p.78) described a well-thought-out front end. A triple-tuned circuit sits between the RF stage and the mixer. The RF and mixer positions use dual-gate MOS-FETs, and another MOS-FET buffers the local oscillator to prevent pulling under strong signal conditions. A delayed AGC helps the tuner cope with high-level antenna input. An LED supplements the frequency readout, for times when tuning slightly off-center is the best way to dodge interference. The review's listening test (p.83) pulled in 53 satisfactory signals with an outdoor antenna. The "AutoFilter" circuit can be left to run itself - when the incoming signal is strong and clean, the filter drops out of the audio path entirely.

Documentation outside the period reviews is thin. Production dates and quantities don't appear to have survived. The DH-330 was a competitively priced, carefully engineered tuner, and like other Hafler products it let you choose between building it yourself and buying it ready to go.