McIntosh C32 Vintage Preamplifier w/Built-In "Monitor Power Amplifier" - SkyFi Overhauled

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

There's so many vintage McIntosh preamp models that it can be confusing which to select for your vintage system. The C32 is the most desirable preamp from this era for several reasons.

The first - it's a preamplifier but it can also power a smaller set of speakers. Seriously!

The C32 contains a "Monitor" amplifier for speakers which can also power electrostatic headphones. From the manual: MONITOR, HEADPHONE, LINE Output: 12 watts per channel, continuous, into 8 ohms.

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 phono section with two dedicated phono inputs lets you connect your turntable without the need for additional gear.

This particular example was completely overhauled in house and is working flawlessly. I am sure we've never seen a nicer C32.

SkyFi Cosmetic Notes:
This preamp is in very good cosmetic condition overall. The only mentionable item that we noticed is some wear on the knobs.

SkyFi Technical Notes:
This preamp received an extensive overhaul here at SkyFi Audio. This device was fully disassembled, each board was serviced, then the entire device was reassembled and rewired with a brand new ribbon cable kit.

We replaced every electrolytic capacitor while the unit was apart with the exception of the large 4700uF filter capacitors for the monitor amplifier.

Select known-to=fail relays in the monitor amplifier and expander boards were replaced.

We also installed a fresh set of lamps and lamp grommets to make the front faceplate illuminate like it was new again.

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:
Second Owner

Connections:
RCA inputs and Outputs, Switched AC outlets

General Sound:
Smooth, uncolored, undistorted natural and clean

Cosmetic Condition:
8/10 = Very Good. Excellent front faceplate, one minor flaw on chassis side or top. See our detailed rating description here.

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

Included:
Just the unit and power cord.

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

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.