HF-85

About the HF-85

The Eico HF-85 is a stereophonic preamplifier produced by Eico (Electronic Instrument Co.Inc.) around 1958 to 1963. It features a tube-based design with 5 x 12AX7/ECC83 tubes and 1 x 6X4 tube rectifier, delivering a frequency response from 5Hz to 200kHz and total harmonic distortion of 0.15%. The unit includes multiple inputs such as microphone, moving magnet phono, and line level, with input sensitivities of 1mV for mic and MM, and 170mV for line. It has a signal-to-noise ratio of 60dB for mic and MM inputs and 75dB for line input. The HF-85 is housed in a metal case with dimensions approximately 3-5/8 x 12 x 8-1/2 inches and weighs about 9.5 lbs. It is AC powered (105-120V) and was designed as a high fidelity stereo preamplifier with a classic tube sound favored by audiophiles. The preamp benefits from recap and power supply upgrades to reduce hum and improve stability. It has a reputation for sweet, articulate sound with a non-cathode follower output stage, and includes tone control feedback and RIAA equalization for phono inputs. Modifications and rebuilds are common to enhance performance and reliability. The HF-85 is considered a classic vintage tube preamp with a dedicated following among HiFi enthusiasts.