McIntosh C26 Solid State Preamplifier - Serviced

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General:
The McIntosh C26 is a well-built vintage solid-state preamplifier that remains a popular choice for both collectors and those putting together a classic hi-fi system. It offers the clean styling and thoughtful design McIntosh is known for and would pair well with the MR78 tuner and MC240 amplifier we also have listed.

Features include dual phono inputs, making it easy to connect two turntables or cartridges without changing cables, as well as dual tape loops for recording or integrating additional components. The rear panel also includes switched and unswitched AC outlets for powering other equipment, making the C26 a flexible preamplifier for a variety of system configurations.

One interesting detail is the original McIntosh Clinic test sticker still intact on the top of the unit, dated May 1973. Most of these stickers were removed over the years, so it's uncommon to find one still in place. It's a nice piece of the unit's history and suggests it was cared for by its original owner.

In testing, the preamplifier performed as it should and all controls operate quietly with no scratchy pots or intermittent switches. This unit has also been serviced in-house, where several age-related components were replaced as preventative maintenance to improve long-term reliability.

As with everything that leaves our shop, it will be packed carefully to ensure it arrives safely.

SkyFi Cosmetic Notes:
There is some wear on the top panel and minor glass blemishes. There is a small number etched into the rear panel. There is also a screw missing on the bottom cover that no longer accepts proper 1/4" screw. Overall for its age it presents well. This listing includes the original inner box.

SkyFi Technical Notes:
This unit was serviced in house here at SkyFi. We replaced the axial electrolytic and tantalum capacitors on the preamp boards, detailed the rear panel jacks, and cleaned the controls. The volume control in this unit tracks surprisingly well. All functions have been tested for proper operation.

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, Speaker Spring Terminals, Power outlets

General Sound:
Smooth, uncolored, undistorted natural and clean

Cosmetic Condition:
7/10 = Good. One or two minor scratches. Well Maintained. See our detailed rating description here.

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

Included:
Unit, manual, and power cord.

Packing:
Will be packed using our highly developed in-house process and custom packing materials.Specs:
Frequency response: 20 Hz to 20 kHz
Total harmonic distortion: 0.1%
Gain: 62 dB (MM), 20 dB (line)
Input sensitivity: 2mV (MM), 250mV (line)
Signal to noise ratio: 74 dB (MM), 85 dB (line)
Output: 250mV (line), 2.5V (Pre out)

Dimensions:
16" x 5.4" x 13" (406.4 x 138.1 x 330mm)

Weight:
31 lbs.

Approximate Age:
1970

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.