McIntosh MA6200 Vintage Integrated Amp - Serviced

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General:
Rather rare integrated amp from McIntosh. We do not get these often, and they are some of our favorites.

Great features include a built-in 90W amplifier with that signature sweet McIntosh sound, a very capable 5-band equalizer, McIntosh Power Guard, dual phono inputs, dual tape loops, and loudness control. 

The 5-band EQ is a particularly fantastic and iconic McIntosh feature, allowing for precise tonal adjustments to better match your room, speakers, and personal listening preferences. Unlike simple bass and treble controls, it offers significantly greater flexibility for fine-tuning the sound, making it easy to get the most out of a wide variety of recordings and listening environments.

As a bonus, this particular amp has been fully serviced by our in-house technician, with all known failure-prone components replaced. All functions now work flawlessly, and it is a joy to use. It also benefits from brand-new glass.

It will be shipped in an original McIntosh carton so it arrives safely at its new home.

SkyFi Cosmetic Notes:
Very light signs of wear on side panels. The original glass faceplate was damaged. It has been replaced with a reproduction piece of glass from the McIntosh factory. Note that the new glass propagates light differently than the original glass resulting in look that is often described as "less bight." Overall Excellent shape.

SkyFi Technical Notes:
The MA6200 was serviced in house here at SkyFi Audio. We replaced the aging electrolytic capacitors in the power supply board, line stage, phono stage, auto on, and amplifier sections. Select lamps were replaced as needed. All controls have been cleaned and all functions verified.

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 Inputs and outputs, captive power cord, convenience power outlets. Spring speaker terminals.

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 and box

Packing:
Original Manufacturers Packing

Specs:
Type Pre-main amplifier
Power Amplifier Unit
Effective output (20 Hz to 20 kHz) 75W + 75W (8 Ω, THD 0.05%)
100W + 100W (4 Ω, THD 0.05%)
Input Sensitivity / Impedance 2.5V/22k Ω
Speaker switching A, B, C
Total harmonic distortion factor 0.05% (0.25W ~ Effective Output, 20 Hz ~ 20 kHz)
Cross modulation distortion factor 0.05% (whole output band, whole circumference fraction)
Frequency characteristic 20 Hz ~ 20 kHz + 0 -0.5 dB
Signal-to-noise ratio 100dB
Damping factor 30
Control Amplifier Section
Input Sensitivity / Impedance Phono1, 2 : 2mV/47k Ω
Tuner, Aux1, 2, Tape1, 2 : 250mV/100k Ω
Output Level / Impedance Rec out:0.25V
Signal-to-noise ratio Phono:80dB
Aux, Tape : 95 dB
Tone control 5-element program equalizer
Center Frequency : 30 Hz, 150 Hz, 500 Hz, 1.5 kHz, 10 kHz
Each ± 12 db variable
Loudness control Continuously variable
Tape monitor Route 2
Tape copy 1 → 2, 2 → 1
Mode selector 7-point switching
Premain separation Possible
GENERAL
Pwer 100 VAC, 50Hz/60Hz
AC outlet Turntable interlock : 2 systems
Power switch interlock : Route 3
Power consumption 400W maximum

Dimensions:
Width 15.98" x Height 5.43" x Depth 12.99"

Weight:
30 lbs.

Approximate Age:
1978

Link to Manual:
Click Here

Recommended Cables:
Kimber Kable - RCA Interconnects - Better

Kimber Kable - RCA Interconnects - Best

Kimber Kable - Phono Interconnects

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 

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 device has the ability to decouple the preamplifier from the power amplifier, we remove the jumpers and independently test each section. If the device cannot be decoupled, we assess the electronic condition of the piece by analyzing the speaker level output only.

We start by connecting the "Pre-Out" jacks of the integrated 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 section 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.

Next we test the power amplifier section by connecting the integrated amplifier speaker outputs 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 "Main In” jacks 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. 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.

If the preamp and power amp both pass these tests, we reconnect the sections and verify that the preamp section can drive the power amp to rated power with a 1KHz tone on one of the line level inputs.

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 moves 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.