McIntosh MX115 Tuner-Preamplifier (1968)

The McIntosh MX115 is a tuner-preamplifier from 1968, and it sits right where McIntosh Laboratory moved from vacuum tubes to solid-state. It puts a high-fidelity preamp and a sensitive FM/AM tuner in one chassis. There is no power amp built in. The preamp design and the tuner section made it a favorite with picky listeners, and it stayed in production until 1977.

It has blue illumination, precision meters and McIntosh build quality, and collectors still go after it.

Key Features

Solid-state design with no tubes
McIntosh Unity Coupled Circuitry for low distortion
Integrated FM/AM tuner with signal strength meter
Separate bass and treble tone controls with loudness contour
Mode and filter switches for enhanced FM reception
Phono inputs for both MM (moving magnet) and MC (moving coil) cartridges
Front-panel 1/4" headphone jack
Illuminated tuning and signal strength meters
High-quality rotary controls and switches

Specifications

Parameter	Specification
Year of Production	1968–1977
Category	Tuner-Preamplifier (Receiver)
Design	Solid-state
Power Output	Preamplifier only (no power amplification)
Tuner Bands	FM, AM
FM Sensitivity	1.7 μV for 30 dB quieting
Phono Input Sensitivity	MM: 2.5 mV for 0.5V output MC: 0.25 mV for 0.5V output
Input Impedance	High-level: 47k ohms MC Phono: 100 ohms
Output Impedance	Fixed: 600 ohms Variable: 47k ohms
Total Harmonic Distortion	<0.1% (typical)
Frequency Response	20 Hz – 20 kHz (±0.5 dB)
Headphone Output	1/4" jack, front panel
Power Requirements	120V AC, 60 Hz
Dimensions (W×H×D)	19" × 6.5" × 15.5"
Weight	28 lbs (12.7 kg)

Historical Context

The MX115 was one of McIntosh's earliest solid-state tuner-preamps. It moved the company from tube electronics to transistorized circuitry without giving up the sound quality and engineering the brand was known for.

FM broadcasting was gaining popularity in the late 1960s and 1970s for its better sound quality, and the MX115 had high sensitivity and selectivity to match. It has both MM and MC phono inputs for serious vinyl listeners. The Unity Coupled Circuit design keeps distortion low and bandwidth wide.

The MX115 was often paired with McIntosh power amplifiers like the MC240 or MC3500. That combination was the core of many high-performance systems in homes and studios. The unit is durable and modular, which helps long-term reliability.

Sound Signature

The MX115 sounds warm, smooth and detailed, and it still holds up by modern standards. The preamp section is known for a low noise floor and excellent channel separation. It preserves the dynamics and spatial cues of the original recording.

The phono stage is widely praised for its musicality and for pulling nuance out of vinyl, which is a good result for a solid-state design of its era. The MC input is sensitive and well matched to low-output moving coil cartridges. The FM tuner gives clear reception with strong stereo imaging and minimal interference, thanks to precise filtering and a sturdy front-end design.

Maintenance and Restoration Tips

The MX115 is known for durability, but units over 40 years old often need servicing to perform at their best. Here are common issues and recommended maintenance steps:

Capacitor Replacement: Electrolytic capacitors in the power supply and audio path degrade over time. A full recapping is strongly recommended to prevent noise, hum, or component failure.
Cleaning Controls: Rotary switches and potentiometers can become noisy due to oxidation. Use contact cleaner designed for audio equipment (e.g., DeoxIT) and exercise the controls repeatedly after application.
Tuner Alignment: If FM reception is weak or unstable, a professional alignment of the tuner section may be necessary.
Meter Lamps: The illuminated tuning and signal strength meters use small incandescent bulbs that may burn out. Replacement bulbs are available from specialty audio restoration suppliers.
Bias and Calibration: Ensure transistor bias points are checked and calibrated during servicing to maintain optimal performance.
Originality Preservation: For collectors, retaining original components and finishes increases value. Use NOS (New Old Stock) or period-correct replacements when possible.

Collectibility and Market Value

The McIntosh MX115 has a collectibility rating of 7/10. It appeals to collectors who focus on the transition era of solid-state development and the early years of high-fidelity FM reception.

Market Value: $300 – $600 USD
Factors Affecting Value:
Original condition (chrome, faceplate, knobs)
Operational status
Service history
Presence of both MC and MM phono functionality
Working meters and illumination

Fully serviced units with clean cosmetics sell for higher prices, especially with original documentation or packaging.

Conclusion

The MX115 sits between the tube era and the solid-state era. It combines a very good preamp, an excellent tuner and McIntosh build quality. Some owners use it in a vintage system, and others keep it as a collector's item.

Market Value

┌──────────────────────────────────────────────────────────────────────────┐
│ MCINTOSH MX115                                                  Nov 2026 │
├──────────────────────────────────────────────────────────────────────────┤
│ High      $37                                     Latest             $21 │
│ Median    $20                                     Trend                — │
│ Low       $12                                     Volume           ~2/mo │
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│    $50 ┤                                                                 │
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│    $29 ┤                                                                 │
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│     $0 ┤                                                                 │
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│    vol │█    ▄▄  ▄  ▄   ▄ ▄▄     ▄                                      ▄│
│        └─────────────────────────────────────────────────────────────────│
│         2026-01                      2026-04                      2026-07│
└──────────────────────────────────────────────────────────────────────────┘

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