McIntosh MA6500 All-Analog Integrated Amplifier - Serviced & Complete

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General:
Recently McIntosh started building DAC's into almost every integrated they make. If you're a purist, you're going to want an integrated that's just that - minus the bells and whistles.

This model hails from the 2000s, and is a solid performer and a great way to get McIntosh magic into your system. A current model 200W integrated from McIntosh would set you back $10,500!

At 200W per side it offers plenty of power to drive most speakers, even the more difficult ones. 

Key McIntosh features include Power Guard and Sentry Monitor protection circuits. Power Guard helps prevent audible clipping by automatically reducing input drive when necessary, while Sentry Monitor provides fuse-free short-circuit protection that automatically resets once normal operating conditions return.

This particular MA6500 also has the benefit of being serviced in-house, where a handful of components were replaced, the meters were calibrated, and new lamps were installed.

It will come as a complete set including its original remote, manual, and McIntosh double shipping-carton for safe transport.

McIntosh Performance Features Include:
• Power Output
Two separate power amplifier channels, each capable of 200 watts and a sophisticated control center in one compact unit with less than 0.005% distortion.
• Power Guard
Both channels include the patented McIntosh Power Guard circuit that prevents the amplifier from being overdriven into clipping with its harsh distorted sound that can also damage your valuable loudspeakers.
• Electronic Input Switching 
Digital Logic integrated circuits drive Electromagnetic switches on all six inputs and operating functions for reliable, noiseless, distortion free switching.

SkyFi Cosmetic Notes:
Overall condition is great with only extremely minor wear. We replaced the meter lamps on this unit, but the meter illumination is still a bit subdued compared to current production McIntosh components.

SkyFi Technical Notes:
This unit arrived in non-working condition. We identified some faulty components in the power supply, along with a several damaged operational amplifiers. We replaced the defective components, calibrated the meters, and replaced the meter lamps. All functions have been tested and 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:
Second Owner

Connections:
RCA, Power control, Speaker Binding Posts, IEC Power input

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:
Unit, Box, Manual, Power Cord

Packing:
Original Manufacturers Packing

Original MSRP:
$4,500.00

Specs:
RMS Power Output (8/4/2 ohms)
120/200/250W min. sine wave continuous average power output per channel from 20Hz to 20kHz with both channels operating
Output Load Impedance
2, 4, or 8 ohms
Rated Power Band
20Hz to 20kHz
Total Harmonic Distortion
0.005% max. at any level from 250 milliwatts to rated power per channel from 20Hz to 20kHz with all channels operating
Intermodulation Distortion
0.005% max. if instantaneous peak power output does not exceed 400W per channel
S/N Ratio (A-Weighted)
Power amp: 110dB below rated output
High level: 100dB below rated output (90dB IHF)
Phono: 90dB below 10mV input (84dB IHF)
Damping Factor
230 (8 ohms) 120 (4 ohms) 60 (2 ohms)
Input Impedance
High level: 22k ohms Phono: 47k ohms, 65pf Main in: 20k ohms
Voltage Gain
High level to tape: 0dB High level to main: 20dB
Dynamic Headroom
2.4dB
Frequency Response
20Hz to 20kHz, +0 / -0.5dB
Maximum Voltage Output
8V from 20Hz to 20kHz
Input Sensitivity
High level: 250mV for 2.5V rated output (50mV IHF)
Phono: 2.5mV for 2.5V rated output (0.5mV IHF)
Main in: 2.5V for rated output
Maximum Input Signal
High level: 10V Phono: 90mV
Power Guard®
Clipping is prevented and THD does not exceed 2% with up to 14dB overdrive at 1kHz
Tone Controls
Bass and treble: ±12dB

Dimensions:
17.5 inches wide (44.5 cm), 7.125 inches high (17.9 cm), and 18.125 inches deep (46 cm)

Weight:
41 lbs.

Approximate Age:
1999

Link to Manual:
Click Here

Recommended Cables:
Kimber Kable - RCA Interconnects - Better

Kimber Kable - RCA Interconnects - Best

Kimber Kable - Phono Interconnects

Kimber Kable - BALANCED XLR Connectors - Better

Kimber Kable - BALANCED XLR Connectors - Best

Kimber Kable - Speaker Cables - Better

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

Kimber Kable - Power Cords - Better

Kimber Kable - Power Cords - 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 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.