McIntosh MC352 Double Balanced Solid State Amplifier with 350W x 2!

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General:
350W powerhouse amplifier in super clean condition and ready to drive just about any speaker you throw at it.

The current almost identical model will set you back $7500.

So what does double balanced actually mean?

"The double balanced configuration cancels virtually all distortion."

More on double balanced from the manual:
"The MC352 is fully balanced from inputs to outputs. Each channel consists of two matched power amplifiers operating in push-pull with their outputs combined in a McIntosh Autoformer."

If you search online you'll find several forum posts that say longtime McIntosh employee and current McIntosh President Charlie Randall actually designed this amplifier.

And that his design spawned the later quad balanced configuration used today in their current amplifiers, and even their DACs!

Tested in our lab and working like new. Cosmetically excellent with only the slightest signs of use.

Please note due to size and weight this item is not covered under our free shipping promos that we offer from time to time.

This MC352 will ship for $400 flat rate freight anywhere within the lower 48 US States strapped to a pallet due to its weight and for safe travels. If you're on the East Coast contact us before your purchase to double-check this rate. Local pickup also welcome, and if you're outside of this area note we can ship worldwide.

We strongly recommend 2-3 friends to help you unbox safely on arrival.

McIntosh Performance Features Include:
DOUBLE-BALANCED PUSH-PULL DESIGN
The MC352 is fully balanced from input to speaker output. Matched amplifiers operate in complementary push-pull with their outputs combined in the McIntosh autoformer. The resulting double-balanced configuration cancels virtually all distortion. 

EXCLUSIVE MCINTOSH OUTPUT AUTOFORMERS
An impedance mismatch between an amplifier and loudspeaker can cause distortion and a reduction in power.

The legendary McIntosh autoformer is a hand crafted transformer with output connections for 2, 4 and 8 ohms (plus 1, 2 and 4 ohms for the MC352's mono parallel mode), allowing an ideal impedance match. A McIntosh amplifier with an autoformer can also safely drive multiple speakers connected in parallel without shortening the life expectancy of the output stage.

There is absolutely no performance penalty with an autoformer. In fact, its frequency response exceeds that of the output circuit itself, and extends well beyond the audible range. Distortion is so low it is virtually immeasurable.

EXCLUSIVE MCINTOSH POWER ASSURANCE SYSTEM
Power Assurance is a collection of technologies that enhance performance and reliability and protect the amp and the loudspeakers.

Power Guard® clipping protection
Power Guard ensures that the amplifier will always deliver full power without causing clipping distortion. If an amplifier channel is overdriven, Power Guard automatically reduces the input volume just enough to keep distortion below 2% and prevent any clipping distortion. Thanks to an optical resistor, Power Guard acts literally at the speed of light, producing absolutely no audible side effects. An amplifier with Power Guard will actually deliver clipping-free output well above its rated power.

Sentry Monitor® current protection
Sentry Monitor continually senses the voltage and current of the output stage and confines it to a safe limit. Sentry Monitor does not limit power output.

Cosmetic Notes:
- Very light marks on metal trim bezels around glass.
- Uneven lighting around power indicator text.
- Marking on top trim cover.

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:
XLR and RCA inputs and outputs, 2, 4 and 8 ohm speaker post accepting banana, spades and bare wire, removable power cord, 12V trigger inputs and outputs

General Sound:
Big beautiful musical sound with little fatigue.

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, manual, and power cord.

Packing:
Original Manufacturers Packing

Reviews:
Click Here

Specs:
Power Output Stereo
350 watts into 2, 4 or 8 ohm loads is the minimum sine wave continuous average power output per channel both channels operating.

Power Output Mono Parallel
700 watts into 1, 2, or 4 ohm loads is the minimum sine wave continuous average power output.

Output Load Impedance
2, 4, or 8 ohms (Stereo Mode) 1, 2, or 4 ohms (Mono Mode)

Rated Power Band
20Hz to 20,000Hz

Dynamic Headroom
2.1 dB

Frequency Response
+0, -0.25 dB from 20Hz to 20,000Hz
+0, -3 dB from 10Hz to 100,000Hz

Total Harmonic Distortion
0.005% maximum at any power level from 250 milliwatts to rated power per channel from 20Hz to 20,000Hz, all channels operating.

Intermodulation Distortion
0.005% maximum if instantaneous peak output per channel does not exceed twice the rated output with all channels operating for any combination of frequencies from 20Hz to 20,000Hz.

Signal To Noise Ratio (A Weighted)
94dB Unbalanced (120dB below rated output)
98dB Balanced (124dB below rated output)

Sensitivity
1.9 Volts Unbalanced Input
3.8 Volts Balanced Input

Input Impedance
20,000 ohms Unbalanced
40,000 ohms Balanced

Damping Factor
Greater than 40

Power Requirements
120 Volts, 50/60Hz at 12.0 amps

Dimensions:
Front Panel: 17.50 inches (44.5cm) wide, 8.89 inches (22.58cm) high. Depth behind front mounting panel is 21 inches (53.3cm) including clearance for connectors. Panel clearance required in front of mounting panel is 1.125 inches (2.9cm).

Weight:
105 lbs.

Link to Manual:
Click Here

Recommended Cables:

Kimber Kable - RCA Interconnects - Better

Kimber Kable - RCA Interconnects - Best

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 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.