McIntosh C108 (1977–1980)
A word of caution before we go any further: “C108” is one of those designations McIntosh applied to two completely different products. The one most collectors mean is the solid-state stereo preamplifier/control amplifier built from roughly 1977 to 1980 (some sources say 1978–1980), originally priced at $1,200 (or $1,200.00 in 1980, per Hi-Fi Engine). There is also a much later C108 car audio electronic crossover network — a 2-way unit with a variable 80Hz–160Hz crossover point and 12 dB/octave slope — that shares the name and little else.
The home preamp is the better-documented of the two, though the record is still modest. It weighs 18 pounds and measures 16 inches wide, 4.6 inches high, and 10.9 inches deep — standard McIntosh proportions for the era, with the familiar black glass front panel. It draws 105 watts. Inputs cover phono, tuner, two tape loops, and aux. Phono sensitivity is 2.5mV with 60dB of gain; line inputs need 250mV. Signal-to-noise is rated at 80dB on phono and 95dB on high level. The phono stage overloads at 80mV at 1kHz, and total distortion is given as less than 0.05%. Outputs include a variable main output and tape outs at 2.5V.
The tone control section is where the C108 gets interesting. It offers bass and treble controls with turnover switching — five bass turnover positions and five treble attenuation positions, per the advertising of the day. High Fidelity (September 1954, p.34) described this flexibility as compensating for “all recording curves use today and any that may be used in the future” — though that phrasing comes from the earlier tube-era C-108 Professional Audio Compensator, and the ad copy was reused for years. The solid-state C108 also includes low and high filters.
Output impedance is a point of mild disagreement between sources: one lists a single 500-ohm figure, while another specifies 50 ohms for the main variable output and 500 ohms for tape. Given the discrepancy, I’d treat the 500-ohm figure as applying to the tape outputs. Frequency response is 20Hz to 20kHz, with one source adding ±0.5dB.
The car audio crossover version is a separate, much later product — a black 2-way electronic crossover measuring 5.12 by 7.88 by 1.0 inches, with input sensitivity from 150mV to 7.5V, a 110dB signal-to-noise ratio, and 0.003% THD. McIntosh’s own product page is the sole source for these figures; no production years or original price are documented.
What’s missing: no detailed circuit topology beyond “solid state” and “Class A/B,” no phono load capacitance figures, no service history or known failure modes, and no collector market data for either version. If you own one and know more, the archive would welcome the correction.
eBay Listings
As an eBay Partner, we earn from qualifying purchases. This helps support our independent vintage technology research.