McIntosh C26 Vintage Analog Preamplifier - Serviced

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General:
This is a great vintage preamp from McIntosh and a good foundation to your system. Would pair up well with the classic vintage MR78 tuner and MC2105 amplifier we also recently listed for sale.

The C26 is a well-equipped preamp, featuring dual phono inputs and tone controls to get the most out of your setup.

This particular C26 has the benefit of being serviced in the past by our good friends and experts at Audio Classics, and has new modern gold-plated RCA jacks in the back. 

All controls are quiet, and all bulbs are working just like they should.

SkyFi Cosmetic Notes:
This unit presents very well overall. Light blemishes are present in the glass near the Panloc buttons and headphone jack.

SkyFi Technical Notes:
"TBH 1977" Official McIntosh Clinic sticker.

This unit was previously serviced by Audio Classics. From our bench evaluation it appears as though the entire rear RCA jack panel was swapped for a gold plated alternative (big upgrade). Some capacitors were also replaced in the power supply.

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:
Accurate to the recording

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.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.