McIntosh C22 Vintage All-Tube Preamplifier - Holy Grail Vintage McIntosh - Serviced

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General:
I enjoy rotating different vintage HiFi gear into my home office, and it's time this vintage Holy Grail from McIntosh a new home for someone else to enjoy as much as I did. I did not take this decision lightly, as this is the nicest C22 we've ever had into the shop and I had it fully serviced and cleaned at SkyFi thinking I would keep it.

I bought this from the original owner several years back years back where it was in use until about 5 years before I found it. It definitely needed a thorough cleaning inside and out (so much dust behind the center clear glass), plus new tubes as described below in our technical notes.

This is the Holy Grail of preamps from McIntosh. 

Likely the most collectible vintage piece from McIntosh, and their top tube preamp.

This gives you all that you want from a vintage preamp and then some in pure analog beauty. 

An all-tube unit providing that warm and engaging vintage sound that so many are after. In very nice cosmetic condition with light signs of use as expected from a well cared for piece from this era. 

This particular unit was meticulously serviced in house and is working flawlessly. This is an absolute must or a vintage C22.

We also purchased a factory fresh McIntosh double-shipping carton to ensure save travels to your home.

SkyFi Cosmetic Notes:
Some marks mostly visible on the side surfaces of the unit. Overall the condition is very good for a piece at about 60 years old!

SkyFi Technical Notes:
I had this C22 fully serviced and cleaned at SkyFi thinking I would keep it long term, with about 8 hours of labor and only the best replacement parts where necessary.

Original Tube Notes on Intake:
V1 - Telefunken Smooth Plate Cross Top:  100/106 - 4, 108/106 - 5
V2 - Telefunken Smooth Plate Cross Top: 116/93, 125/112 - 2.5 (Microphonic), - 5
V3 - Telefunken Smooth Plate Smooth Top: 58/81 - 4, 50/75 - 4
V4 - Sovtek 12AX7, WEAK Replace: 41/50, 5, 8/25 - 5
V5 - Telefunken Smooth Plate Cross Top: 33/37 4, 66/81 - 4
V6 - Telefunken Smooth Plate Smooth Top: 83/75 - 4, 75/87 - 5

Final Installed Tube Compliment:
V1 - (Old V6) Telefunken Smooth Plate Smooth Top: 83/75 - 4, 75/87 - 5
V2 - (Old V3)  Telefunken Smooth Plate Smooth Top: 58/81 - 4, 50/75 - 4
V3 - SkyFi Telefunken Smooth Plate Smooth Top 75/93, 66/87
V4 - SkyFi Telefunken Smooth Plate Smooth Top 83/81 - 5, 66/68 - 4
V5 - SkyFi Telefunken Smooth Plate Smooth Top 83/87 - 4, 75/93 - 5
V6 - (Old V1) Telefunken Smooth Plate Cross Top:  100/106 - 4, 108/106 - 5

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, Power outlets, Captive Power cord

General Sound:
Big beautiful musical sound with little fatigue.

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:
Unit and new McIntosh double-shipping carton

Packing:
Original Manufacturers Packing

Specs:

Frequency Response
±0.5 dB from 20 cps to 20,000 cps

Distortion
Less than 0.2% at 10 volts output, 20 to 20,000 cps
Less than 0.02% at 3 volts output, 20 to 20,000 cps

Hum and Noise
High-level inputs: 85 dB below rated output
Low-level inputs: Less than 1.5 microvolts at input terminals

Input Sensitivity and Impedance
Auxiliary, Tape, Tuner 1, Tuner 2: 0.25 volts, 250,000 ohms
Phono 1, Phono 2: 2 millivolts, 47,000 ohms
Microphone: 2.5 millivolts, 1 megohm
Tape Head: 2 millivolts, 1 megohm
Tape Compare: 0.25 volts, 250,000 ohms

Outputs
Main (two jacks per channel): 2.5 volts at rated output
Tape: 0.25 volts at rated output
Left + Right: 1 volt from generator impedance of 25,000 ohms

Voltage Amplification
Auxiliary, Tape, Tuner 1, Tuner 2:
– To Main Output: 20 dB (10:1)
– To Tape Output: 0 dB (1:1)

Phono 1 and Phono 2 (at 1 kc):
– To Main Output: 62 dB (1250:1)
– To Tape Output: 42 dB (125:1)

Microphone:
– To Main Output: 60 dB (1000:1)
– To Tape Output: 40 dB (100:1)

Tape Head (at 500 cps):
– To Main Output: 62 dB (1250:1)
– To Tape Output: 42 dB (125:1)

Auxiliary AC Outlets (5)
1 unswitched outlet for turntable or tape machine (red)
4 switched outlets (black)

Power Requirement
117 volts AC, 50/60 cps
34 watts

Tubes
Six 12AX7 tubes

Tape Jack Switch
Two-position switch allowing signals to be fed to or from the C22 for recording or playback with an external portable tape recorder

Bass Controls
Separate channel, 11-position switch type
±20 dB at 20 cps

Treble Controls
Separate channel, 11-position switch type
±20 dB at 20,000 cps

Compensator Switch
RIAA or LP record equalization

Tape Switch
Normal or Tape Monitor

Rumble Filter
50 cps cutoff

High-Frequency Filter
5,000 cps cutoff

Additional Setup Controls
Located behind the front panel on the top of the C22 chassis and accessible by depressing the PANLOC buttons

Output Level Controls (L, L+R, R)
Allows overall system balance adjustment

Low-Frequency Trim Controls (L, R)
Allows frequencies below 100 cps to be boosted up to 6 dB

Tape Equalization Controls (L, R)
Adjust tape head input high-frequency response

Phase Switch
Two-position: normal (0°) or reverse (180°)

Dimensions:
16 x 5-7/16 x 13 inches

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.