McIntosh C22 Vintage All-Tube Preamp - Collectors Edition - SkyFi Restored
This is the Holy Grail of preamps from McIntosh.
This is also the cleanest and best looking C22 to come through our shop by far.
This is an all tube unit, not a hybrid, that provides the warm and engaging vintage sound that so many are after.
This is *not* the C22 re-issue from several years back and is even harder to find especially in this condition!
This C22 comes complete with its wood cabinet, and a hard copy of the original manual from the 1960's! Please note that the original sales brochure photos are online only, and not included as hard copies.
SkyFi Restoration Outline:
This C22 just went through and extensive in-house restoration. This example was previously worked on at one of the former and official McIntosh clinics.
The clinic work consisted of the addition of some capacitors under the chassis, and bypassing some dead capacitor sections. Upon further investigation we found that at least two more multi-section capacitor sections had since failed. This example also featured Selenium rectifiers for the both the filament and B+ supplies. We opted for a full power supply rebuild to bring this unit back up to spec.
The power supply rebuild included all new custom made multi-section filter cans. We also swapped the selenium rectifiers for silicon with proper compensating components in place. Each and every power supply resistor was been replaced with period correct new production carbon composition and wire wound parts.
We also thoroughly reviewed the signal path components in this example, testing all resistors for accuracy, and all caps for value and leakage.
In all, we replaced (2) axial electrolytics, (2) resistors, and (2) caps that were out of spec.
All other parts were left original to preserve the sonic character of this piece.
On final testing we noticed some source bleed on the phono inputs and opted to add 10K resistors to each input. (These resistors were indicated in the service manual as only present on later serial number examples. Our guess is that this piece was early production and did not receive this modification, which was eventually applied to all late production C22's at the factory in Binghamton).
This C22 came to us with a complete set of current production Sovtek 12AX7 tubes which we left in place. We also added high-quality LED "festoon" type indicator lamps for the dial glass to replace the burnt out incandescent lamps/prevent further need for replacement.
±0.5 db from 20 cps to 20,000 cps.
Less than 0.2% at 10 volts output, 20 to 20,000 cycles. Less than .02% at 3 volts output, 20 to 20,000 cycles.
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, and Tuner 2: 0.25 volts, 250,000 ohms. Phono 1 and 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.
Main (2 jacks on each channel) : 2.5 V with rated output. Tape: 0.25 V with rated output. Left Plus Right: 1 V from generator impedance of 25,000 ohms.
Auxiliary, Tape, Tuner I, and Tuner 2: To Main Output, 20 db (10 to 1).
To Tape Output, 0 db (1 to 1). Phono 1 and Phono 2 (At 1 KC): To Main Output, 62 db (1250 to 1). To Tape Output, 42 db (125 to 1). Microphone: To Main Output, 60 db (1000 to 1). To Tape Output, 40 db (100 to 1). Tape Head (At 500 cps): To Main Output, 62 db (1250 to 1). To Tape Output, 42 db (125 to 1).
AUXILIARY AC OUTLETS (5)
1 unswitched for turntable or tape machine (Red), 4 switched (Black).
117 volts 50/60 cps AC, 34 watts.
6 each 12AX7.
TAPE JACK SWITCH
2 position, connects panel jacks to allow signals to be fed from or to the C22 to record or playback using an external portable tape recorder.
Separate channel 11 position switch type,± 20db at 20 cycles.
Separate channel 11 position switch type,±20 db at 20,000 cycles.
COMPENSATOR SWITCH RIAA or LP record equalization.
TAPE SWITCH Normal, or Tape Monitor.
RUMBLE FILTER 50 cps cutoff.
HF FILTER 5000 cycle cutoff.
ADDITIONAL SET·UP CONTROLS
The following controls are located behind the front panel on the top of the C22 chassis. These controls are readily accessible by depressing the PANLOC buttons to slide the C22 forward from the mounting panel.
OUTPUT LEVEL CONTROLS (L, L+ R, AND R)
Allows the balance of the enti re system to be conveniently adjusted.
LOW FREQUENCY TRIM CONTROLS (L AND R)
Allows frequencies below 100 cps to be boosted up to 6 db
TAPE EQUALIZATION CONTROLS (L AND R) Adjusts tape head input high frequency response.
2 position, normal (0°) or reverse (180°).
PILOT LAMP INTENSITY SWITCH 2 position, bright or dim.
Front panel; 16 inches wide by 57/16inches high; chassis (including PANLOC shelf) 15 inches wide by 5 inches high by 13 inches deep, including connectors; clearance in front of mounting panel including knobs,lYz inches.
16 pounds net, 25 pounds in shipping carton.
The SkyFi Testing Process for Preamplifiers:
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. Special attention is paid to the power supply which is the most common source of failure for preamps. We then power up the unit and run a simple 1k sine wave while monitoring the low voltage output on an oscilloscope for signs of distortion or noise to get a baseline.
At this point we will lubricate and clean all switches and potentiometers (that are not sealed) with a high quality contact cleaner, and then re-test all functions for any signs of noise or scratching.
Final testing involves putting actual music through the preamplifier We have learned over time that some issues are only noticeable to a trained ear while listening to a familiar source material. Our test bench has reference vintage KEF speakers that we are super familiar with which will quickly reveal any discrepancies. Some preamps will then move into the listening room where they will be tested with our in-house reference system.
Please click here for detailed specifics regarding our specialized packing process that separates us from the rest.
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