McIntosh C40 (1993)
A solid-state audio control center with built-in monitor amplifier, released in March 1993
Overview
The McIntosh C40 is an audio control center and preamplifier with a built-in 20W + 20W monitor amplifier, manufactured by McIntosh Laboratory. Released in March 1993, it combines high-fidelity signal routing with onboard amplification for direct speaker drive. Designed for both stereo and specialized listening setups, it includes eight unbalanced inputs, processor loops, and a 5-band equalizer with ±12 dB adjustment. The unit features digital logic-controlled reed relays for all signal switching and includes Power Guard protection in the monitor amplifier section to prevent distortion.
Specifications
| Year of Production | 1993 |
| Product type | Audio control center / Preamplifier (with built-in monitor amplifier) |
| Frequency response | 20 Hz to 20,000 Hz, +0 -0.5 dB |
| Rated output | 2.5 V (main, balanced output) |
| Output impedance | 600 Ω (main, balanced output) |
| Maximum output voltage | 8 V (main, balanced output, 20 Hz to 20,000 Hz) |
| Total harmonic distortion | 0.002% maximum (20 Hz to 20,000 Hz at rated output) |
| Input sensitivity Phono | 2.5 mV (at 2.5 V rated output) |
| Input sensitivity High level | 250 mV (at 2.5 V rated output) |
| Signal-to-noise ratio (A-weighted) Phono | 90 dB (for input up to 10 mV) |
| Signal-to-noise ratio (A-weighted) High level | 105 dB (below rated output) |
| Maximum input signal Phono | 90 mV |
| Maximum input signal High level | 10 V |
| Input impedance Phono | 47 kΩ, 65 pF |
| Input impedance High level | 22 kΩ |
| Voltage gain Phono → Tape | 40 dB |
| Voltage gain High level → Tape | 0 dB |
| Voltage gain Phono → Main | 60 dB |
| Voltage gain High level → Main | 20 dB |
| Equalizer control | 5-band, ±12 dB at 30 Hz, 150 Hz, 500 Hz, 1.5 kHz, 10 kHz |
| Monitor Amplifier Section Output | 20 W + 20 W (8 Ω, 20 Hz-20,000 Hz) |
| Monitor Amplifier Section Total harmonic distortion | 0.005% maximum (250 mW to rated output) |
| Monitor Amplifier Section Frequency response | 20 Hz to 20,000 Hz, +0 -0.5 dB |
| Monitor Amplifier Section Input Sensitivity / Impedance | 750 mV / 27 kΩ |
| Monitor Amplifier Section Signal-to-noise ratio (A-weighted) | 100 dB (below rated output) |
| AC power outlets | 4 switched, 1 unswitched |
| Power requirements | 100 VAC, 50 Hz/60 Hz |
| Power consumption | 25W ~ 58W |
| Dimensions (W x H x D) | 445 x 137 x 432 mm (including terminals) |
| Panel operating clearance | 38 mm |
| Weight | 12 kg |
Design
All signal switching in the C40 uses sealed reed relays controlled by digital logic. The 5-band equalizer allows ±12 dB boost or cut, with a center position that bypasses the circuit for flat response. It includes a compander system with expansion and compression modes for dynamic range compensation and active loudness control adjustable independently of the master volume. The phono equalizer uses 1% tolerance resistors to ensure low RIAA deviation. The front panel is glass with gold and teal blue lighting. The unit is compatible with the optional SCR-3 relay unit for speaker switching and amplifier power control and includes an external input terminal for use with surround amplifiers. The built-in monitor amplifier features a Power Guard circuit that compares input and output waveforms and reduces level to prevent distortion.
Product Family
The McIntosh C40 is categorized as a "Classic Model" and "Preamplifier" in the McIntosh lineup.
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