McIntosh MC2105 Vintage Amplifier - Serviced With New Glass

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General:
The MC2105 is one of our best selling amps and a true McIntosh workhorse.

Classic McIntosh looks and sound - but with a vintage feel.

Absolutely gorgeous, and capable of powering most modern and vintage speakers. 

This MC2105 is working perfectly and looking great.

Priced accordingly, so if you're looking for an unserviced bargain on a 50+ years "young" piece of audio excellence, please look elsewhere. 

This will ship In a new official double McIntosh box which is the only way to ensure safe transport with their gear. 

SkyFi Cosmetic Notes:
- The original glass was damaged and was replaced with a current production piece of glass from the factory.
- The new glass does not propagate light in the same way as the original so text may appear dimmer than original glass.
- Scratching and scuffing to transformer covers.
- Speaker terminal strips both have barrier damage.
- Light chrome wear.

Service Notes:
- This MC2105 was previously serviced by Analogique. They replaced the capacitors on the driver board and performed the McIntosh service bulletin modifications to the driver boards. They also replaced the speaker on/off switch.

SkyFi Service Notes:
- We corrected an issue with the driver cards related to undersized heat sinks on the driver transistors.
- We also replaced both axial capacitors and increased the power handling on the large 3.6K resistor on the driver cards.
- All service bulletin modifications now correct.
- Glass replaced.
- 4 Burnt out lamps replaced.

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 inputs, captive power cord, screw terminals for speaker cables.

General Sound:
Big beautiful musical sound with little fatigue.

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:
Just the unit and power cord.

Packing:
Original Manufacturers Packing

Specs:
McIntosh Performance Limits and Ratings
PERFORMANCE
McIntosh audio power ratings are in accordance with the Federal Trade Commission Regulation of November 4, 1974 concerning power output claims for amplifiers used in home entertainment products.

POWER OUTPUT
105 watts minimum sine wave continuous average power output, per channel, both channels operating into 4 ohms, 8 ohms, or 1.6 ohms load impedance, which is: 
20.5 volts RMS across 4 ohms
29.0 volts RMS across 8 ohms 
41.0 volts RMS across 16 ohms

OUTPUT LOAD IMPEDANCE
4 ohms, 8 ohms, or 16 ohms; separate terminals are provided for each output

RATED POWER BAND
20 Hz to 20,000 Hz

TOTAL HARMONIC DISTORTION
0.25% maximum harmonic distortion at any power level from 250 milliwatts to 105 watts per channel from 20 Hz to 20,000 Hz, both channels operating

INTERMODULATION DISTORTION
0.25% if instantaneous peak power output is 210 watts or less per channel with both channels operating for any combination of frequencies 20 Hz to 20,000 Hz

FREQUENCY RESPONSE
20 Hz to 20,000 Hz +0 -0.25 dB
10 Hz to 100,000 Hz +0 -3.0 dB at one watt output

NOISE AND HUM
90 dB below rated output

OUTPUT POWER MONITOR METER
Meter is calibrated to read +3 dB when amplifier produces 105 watts. Meter range switch is provided to increase meter sensitivity by 10 dB or 20 dB Calibration accuracy at 0 dB reading is ±2% at all frequencies; meter range accuracy is ±5%

RATINGS
OUTPUT VOLTAGES
25 volts for distribution lines

DAMPING FACTOR
13 at 8 ohms output 18 at 4 ohms output 10 at 16 ohms output

INPUT IMPEDANCE
200.00 ohms

INPUT SENSITIVITY
0.5 volt. Level control provided for higher input voltage

GENERAL INFORMATION
POWER REQUIREMENTS
120 volts 50 60 Hz, 75 watts at zero signal output, 430 watts at rated output

SEMICONDUCTOR COMPLEMENT
34 silicon transistors
18 silicon rectifiers and diodes

MECHANICAL INFORMATION

FINISH
Front panel is anodized gold and black with special gold teal nomenclature illumination. Chassis is chrome and black

MOUNTING
Exclusive Mclntosh developed professional PANLOC

WEIGHT
65 pounds (29.48 kg) net, 77 pounds (34,93 kg) in shipping carton

SPECIAL FEATURES
The amplifier is completely stable when connected to any loudspeaker system or even to any reactive loads; The MC 2105 has special circuits to prevent damage by short circuit or open circuit of the output loads, or by any amount of output impedance mismatch, Thermal cutouts are mounted on the output transistor heat sinks to provide protection in the event of inadequate ventilation.
Peak reading - peak locking meters feature special circuit to respond to peak value of complex input signal

Dimensions:
Front panel measures 16 3/16 inches wide (41,12 cm) by 71/8inches high (18,1 cm). Chassis measures 15 inches wide (38,1 cm) by 6 9/16 inches high (16.67 cm) by 141⁄2 inches deep (36.83 cm), including connectors. Knob clearance required is 11⁄2 inches (3.81 cm) in front of mounting panel

Weight:
65 lbs.

Approximate Age:
1975

Link to Manual:
Click Here

Recommended Cables:

Kimber Kable - RCA Interconnects - Better

Kimber Kable - RCA Interconnects - Best

The SkyFi Testing Process for Solid State Amplifiers:

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 1KHz 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 1KHz square wave check and a 20Hz to 20KHz 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. 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.