McIntosh MC2100 Vintage Solid State Amplifier - SkyFi Serviced

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General:
This is one of the first series of McIntosh Solid State amplifiers, designed and created with ideas and tech learned from their amazing tube amplifiers of the era. The MC2100 was produced from 1969 through 1978.

It resembles the MC240 or MC275 classic tube look, but with solid state "space-age" technology of the day. 

Offering that sweet McIntosh signature sound with 105WPC (or 210W in mono) in conjunction with 0.25% or less THD. Yes that's with both channels driven and measured from 20 Hz to 20,000 Hz.

This particular MC2100 was serviced in house and is now functioning beautifully and sounding excellent.

SkyFi Cosmetic Notes:
This amplifier has light wear on the transformers and chassis. Both output barrier strips have broken barriers between the Common and 4 ohms areas. The cage has a small deformation on the top surface. Overall the condition is good.

SkyFi Technical Notes:
This amplifier was serviced in house here at SkyFi. We replaced the electrolytic capacitors on the input board, and performed preventative maintenance on the driver boards (New caps and select resistors). All transistors in this device are original.

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:
Single Owner

Connections:
RCA input, Speaker Binding Posts

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

Packing:
Will be packed using our highly developed in-house process and custom packing materials.Specs:
105 WPC stereo
210 W monoural

Frequency Response:
20 Hz - 20 kHz
(+0 – 0.25 dB)

Distortion:
0.25%

Noise and Hum:
-90dB

Output Impedance:
4, 8, and 16 ohms stereo
2, 4, and 8 ohms mono

Damping Factor:
11

Input Impedance:
200k

Input Sensitivity:
0.5v

McIntosh Included Patented Features:
Sentry Monitor
Autoformers

Dimensions:
7-3/4" H x 11-3/4" W x 17" D

Weight:
57 lbs.

Approximate Age:
1970

Link to Manual:
Click Here

Recommended Cables:
Kimber Kable - RCA Interconnects - Better

Kimber Kable - RCA Interconnects - Best

Kimber Kable - Speaker Cables - Better

Kimber Summit Series Monocle XL Speaker Cables (PAIR) - Best

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.

If the amplifier passes visual inspection, we move on to a controlled power on sequence using a Sencore safety analyzer to monitor current draw in real time. Once the amplifier is determined to be safe to operate, we connect it to full AC mains for function and power testing. We connect the speaker outputs of the amplifier to a Sencore PA81 Power Analyzer which acts as a dummy load, DC offset monitor, and oscilloscope interface. We start with a low level 1 KHz test signal at the amplifier's input and slowly increase its amplitude while monitoring the output on an oscilloscope for signs of noise, clipping, distortion, or improper channel balance. We continue increasing the signal level until the amplifier reaches clipping.

At this point we take an output power measurement and compare it to the spec sheet of the amplifier to verify proper performance. If the device under test has both balanced and single ended inputs they are both tested at this time.

We finish off the bench evaluation with a 1 KHz square wave check and a 20 Hz to 20 KHz sine sweep to assess the amplifier's frequency response characteristics.

This battery of tests will usually reveal if the amplifier has any issues that need further attention.

Before the device leaves the bench, we perform a listening test with actual music using a variety of preferred test tracks. Our benches are outfitted with familiar monitor speakers which help us identify inconsistencies that will not always show up on our test gear. The main things that we are listening for are hum or noise with no signal present, proper center image, clicks, pops, or any other obvious undesirable audio characteristics.

If the unit passes all of these tests it is moved to our long term testing rig where we simulate real word operating conditions for 6-8 hours minimum. This allows us to monitor the unit for signs of thermal runaway or intermittent issues that only crop up when the unit has fully come up to temperature.