Adcom GFP-1
Documentation on the Adcom GFP-1 preamplifier is thin. The model left no service manual trail and few period references.
HiFI-Stereo (September 1981, p.48) tested the GFP-1 and reported that it had inputs for two magnetic phono cartridges and two high-level sources, labeled TUNER and AUX. Output noise with the high-level inputs was below the meter's 100-microvolt floor, so it was effectively unmeasurable. The tone controls had an unusually wide range: approximately ±20 dB at 30 Hz and ±15 dB at 20,000 Hz, with the response curves hinged at 3,000 Hz.
An updated version, the GFP-1A, appeared by late 1983. Audio (October 1983, p.82) described it as "virtually two preamplifiers in one". A later HiFI-Stereo (March 1984, p.37) test of the 1A found the tone controls to be rare exceptions to the rule that tone controls are more trouble than they're worth. It also reported flawless CX playback with no audible pumping.
Production years and original pricing for the original GFP-1 are unrecorded in the sources available to the Archive. The unit appears to have been a short-lived first-generation model, superseded quickly by the GFP-1A.
Known specifications (from period reviews):
- Two magnetic phono inputs, two high-level inputs (Tuner, Aux)
- Tone controls: ±20 dB at 30 Hz, ±15 dB at 20 kHz, hinged at 3 kHz
- Output noise (high-level inputs): below 100 µV (unmeasurable on test bench)
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