McIntosh MC7108 8-Channel Configurable Power Amplifier

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General:
The McIntosh MC7108 is an unusually flexible multi-channel power amplifier that can be configured for 4, 5, 6, 7, or 8-channel operation, making it well suited for a wide range of stereo and home theater systems.

In its standard configuration, it provides up to eight 40-watt channels. Channel pairs can also be bridged to deliver 100 watts per channel, allowing you to trade channel count for higher output power depending on your system needs.

MC7108 Output Configurations:

8-Channel Mode:
8 x 40W

7-Channel Mode:
6 x 40W + 1 x 100W bridged channel

6-Channel Mode:
4 x 40W + 2 x 100W bridged channels

5-Channel Mode:
2 x 40W + 3 x 100W bridged channels

4-Channel Mode:
4 x 100W bridged channels

Each 100W output is created by bridging a pair of amplifier channels.

Bridged operation is rated for 4-ohm loudspeaker loads.

This example  is in excellent cosmetic condition and was fully tested in our lab, where it performed properly across all channels.

Service Notes:
• Channel 1 volume trimmer replaced
• All lamps replaced

Cosmetic Notes:
• Light marks on the end caps and metal trim surrounding the glass

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 and output jacks, screw terminals for speakers, captive power cord. 12V triggers.

General Sound:
Accurate to the recording

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:
POWER OUTPUT, EIGHT CHANNELS
40 watts per channel, minimum sine wave continuous average power output per channel, all channels operating into 4 ohm loads.

The output RMS voltage is:
12.6V across 4 ohms

POWER OUTPUT, TWO CHANNELS BRIDGED
100 watts into a 4 ohm load, minimum sine wave continuous average power output.

The output RMS voltage is:
20V across 4 ohms

OUTPUT LOAD IMPEDANCE
8 or 4 ohms, for all eight separate channels
8 or 4 ohms, for all Bridged Pairs

RATED POWER BAND
20H2 to 20,000Hz

TOTAL HARMONIC DISTORTION
0.005% maximum harmonic distortion at any power level from 250mW to rated power per channel from 20Hz to 20,000Hz, all channels operating.

IHF DYNAMIC HEADROOM
1.8dB

FREQUENCY RESPONSE
+ 0, -0.25dB from 20Hz to 20,000Hz
+ 0, -3.0dB from 10Hz to 100,000Hz

INPUT SENSITIVITY
1V, (2.5V with Level control at center detent)

A WEIGHTED SIGNAL TO NOISE RATIO
92dB (112dB below rated output)

INTERMODULATION DISTORTION,SMPTE
0.005% maximum if instantaneous peak power does not exceed twice the output power rating per channel, with all channels operating, for any combination of frequencies from 20Hz to 20,000Hz.

WIDE BAND DAMPING FACTOR
200 at 8 ohms
100 at 4 ohms

INPUT IMPEDANCE
20,000 ohms

POWER GUARD
Clipping is prevented and THD does not exceed 2% with up to 14dB overdrive at 1000Hz.

POWER REQUIREMENTS
120V, 50/60Hz, 8A UL/CSA

Dimensions:
Front panel: 17-1/2 inches (44.5cm) W, 7-1/16 inches (17.9cm) H, 20 inches (50.8cm) D behind mounting panel, including clearance for connectors. Panel clearance required in front of mounting panel is 3/4 inch (1.9cm).

Weight:
40 lbs.

Approximate Age:
1998

Link to Manual:
Click Here

Recommended Cables:

Kimber Kable - RCA Interconnects - Better

Kimber Kable - Speaker Cables - Better

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

Kimber Summit Series BiFocal XL Bi-Wire Speaker Cables (PAIR) - Best If Applicable 

Kimber Kable - Power Cords - Better

Kimber Kable - Power Cords - 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.