McIntosh MAC1900 Vintage Receiver - Serviced and Ready to Wow

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Our favorite vintage Mc receiver, because of both its looks and operation. Also referred to as the MAC1900.

Serviced and ready for another decade of operation.

Super clean example. Possibly the nicest one we've seen.

Service Notes: This unit underwent a routine service in August 2020. This included the replacement of 10 electrolytic capacitors, lamp replacement where required, cleaning of all controls, chassis and faceplate cleaned and detailed. All inputs and outputs were tested, and both AM and FM are working well.

Original MAC-1900 Owner's Manual

Original MAC-1900 "If You're a Hurry" Guide

Original MAC-1900 Service Manual

The SkyFi Testing Process for Receivers:
We start with a visual inspection of all internal components to make sure there are no signs of stress or aging. Capacitors are checked for telltale sings of bulging or leaking, resistors are checked for signs of overheating or cracking, and transistors are checked for signs of stress or damage.

We then power up the unit carefully and run a simple 1k sine wave while monitoring the output on an oscilloscope for signs of distortion or noise. Finally, we run the receiver to its full rated power into the appropriate resistive load provided by our Sencore amplifier tester. If there is an issue, it will usually be noticeable at this point. If everything reads clean, we will often test for THD (Total Harmonic Distortion) measured by our Keithley distortion meter, and compare it against the original manufacturers specifications. The receiver then remains powered on to "burn in" on our test bench for a few hours to make sure there are no heat related issues. If there are balanced inputs available they will be also be tested.

Then the tuner is thoroughly tested in our lab utilizing our professional Sencore SG80 FM Generator, which allows us to generate a reference FM signal of any frequency and amplitude, and then measure the resulting tuner output on our Sencore PR81 or oscilloscope.

Final testing involves pushing actual music thorough the receiver. We've learned over time that some issues are only noticeable to a trained ear while listening to familiar source material. Our test bench has reference vintage KEF speakers that we're very familiar with which quickly reveal any discrepancies. Some receivers will then move into our listening room where they are tested with our in-house reference speakers of choice.

Specifications:
Tuning range: FM, AM
Power output: 55 watts per channel into 8Ω (stereo)
Frequency response: 20Hz to 20kHz
Total harmonic distortion: 0.2%
Damping factor: 50
Input sensitivity: 2mV (MM), 250mV (line)
Signal to noise ratio: 76dB (MM), 90dB (line)
Output: 250mV (line)
Speaker load impedance: 4Ω to 16Ω
Semiconductors: 3 x IC, 53 x transistors, 39 x diodes, 4 x thyristors
Dimensions: 15.99" x 5.51" x 15" (406 x 140 x 381mm)
Weight: 33 lbs. (14.97kg)
Finish: Black and gold anodized front
Years: 1972-1975