McIntosh C32 Vintage Preamp w/Phono and EQ - SkyFi Serviced

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General:
The C32 is a full featured preamp with just about every function you could want for a complete system.

If you have vintage speakers or want to get a bit more out of your modern speakers, then you'll likely appreciate the front mounted 5-band EQ built into this preamp.

The built-in phono section lets you connect your turntable without the need for additional gear.

This nice example received a service at our shop including new an official McIntosh replacement front glass faceplate. It's now working and sounding wonderful. 


SkyFi Cosmetic Notes:
This preamp came to us with broken glass. The was replaced with a reproduction piece sourced directly from the McIntosh factory. The new glass propagates light differently than original glass so the brightness and color of the indicator lamps and lettering may appear muted or more dim than an original 1970's glass faceplate. 

The jacks on the rear panel have lost most of their plating, and the top cover shows some wear. 

Overall good condition for its age.

SkyFi Technical Notes:
This preamp was serviced in-house at SkyFi Audio. In additional to our regular maintenance, we installed select replacement ribbon cables and replaced select electrolytic capacitors and relays as needed.

Brand Background:
McIntosh Laboratory is an American manufacturer of handcrafted high-end audio equipment based in Binghamton, New York. The company was founded in 1949 by Frank McIntosh. The company designs and produces audio amplifiers, stereo tuners and other consumer electronics products.

Ownership:
Single Owner

Connections:
RCA inputs and Outputs, Switched AC outlets

General Sound:
Smooth, uncolored, undistorted natural and clean

Cosmetic Condition:
6/10 = Fair. Three to four minor scratches, or one major scratch. See our detailed rating description here.

Working Condition:
Working perfectly and tested in our lab and listening room.

Included:
Just the Unit

Packing:
Will be packed using our highly developed in-house process and custom packing materials.Original MSRP:
$1,659.00 (1977 ~ 1982)

Specs:
Frequency response: 20 Hz to 20 kHz
Total harmonic distortion: 0.05%
Gain: 62 dB (MM), 20 dB (line)
Input sensitivity: 2mV (MM), 250mV (line)
Signal to noise ratio: 90 dB (MM), 100 dB (line)
Output: 250mV (line), 2.5V (Pre out)

Dimensions:
16" x 5.4" x 13" (406 x 138 x 330mm)

Weight:
26 lbs.

Approximate Age:
1977

Link to Manual:
Click Here

Recommended Cables:
Kimber Kable - RCA Interconnects - Better

Kimber Kable - RCA Interconnects - Best

Kimber Kable - Phono Interconnects

Testing Process:
We start with a visual inspection of all internal components to make sure that there are no signs of heat stress or damage. Capacitors are checked for telltale signs of predictive failure including bulging, shrunken wrappers, or physical leakage. We also inspect the PCBs for discoloration from resistors or transistors that may have been running hot. On vintage units we often spot check select capacitors for value and ESR.

When we first power on a preamplifier we connect its RCA output to a Sencore PA81 Power Analyzer which simulates real world loading conditions and gives us an oscilloscope interface.

The first order of business is checking that the volume control works smoothly throughout its entire range with acceptable channel balance. This is accomplished by feeding a 1 KHz sine wave into one of the preamp’s line level inputs while monitoring the preamp’s output on an oscilloscope.

We then switch to a 1 KHz square wave to test the tone controls, loudness function, and filters where applicable. During this step we are watching for equal alteration of the test signal by both channels. This also helps us identify dirty controls that will need treatment.

Once the basic line stage functions are verified, we test each input individually. This is especially important for devices that use relays to select their sources. If the preamp is equipped with a phono stage we test that as well. We use an inverse RIAA filter which allows us to feed a reference test signal into the phono input with the proper RIAA equalization and level. A square wave or sine sweep is used to verify that the device’s phono stage is faithfully reproducing the RIAA curve. If the preamp under test has balanced inputs and/or outputs these are tested as well.

We finish up our bench testing with a listening test with our bench amplifier and reference speakers. During this test we check for hum or hiss that may not have shown up in earlier testing. We also check that all of the tone controls and filters perform as expected.

If the preamplifier has remote control functions these are also tested. Preamps with tube circuits or complicated power supply topologies are connected at our long term test rig for extended stress testing under real world conditions.