McIntosh MA6450 Integrated Amplifier - New Old Stock Sealed box

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General:
This McIntosh MA6450 integrated is in rare new old stock sealed box condition.

It has been laying in its McIntosh box untouched for about 25 years (so far) in a climate controlled location. 

The MA6450 is already a rare integrated amplifier from McIntosh, produced only from 1998-1999. This is the first very first one into our shop and it's a new old stock example!

It features the typical McIntosh beautiful blue VU meters, is fully solid state with the signature McIntosh sound, and is capable of 100 watts per channel. This makes it perfect for most speakers on the market.

This was part of a recent purchase of four different NOS McIntosh models from the same collector and we are in the process of listing them all on our site.

McIntosh Performance Features Include:
• 100 Watt per Channel Integrated Amplifier
The MA6450 combines 100 watt per channel power amplifier with a sophisticated control center in one compact unit.

• Multiple Inputs
Seven high level inputs provide for all popular program sources.

• Power Guard with Sentry Monitor
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. Sentry Monitor power output stage protection circuits ensure the MA6450 will have a long and trouble free operating life.

SkyFi Cosmetic Notes:
Box shows some wear. Unit is brand new.

McIntosh Performance Features Include:
• 100 Watt per Channel Integrated Amplifier
The MA6450 combines 100 watt per channel power amplifier with a sophisticated control center in one compact unit.

• Multiple Inputs
Seven high level inputs provide for all popular program sources.

• Power Guard with Sentry Monitor
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. Sentry Monitor power output stage protection circuits ensure the MA6450 will have a long and trouble free operating life.

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, Speaker Binding Posts, Two power outlets

Cosmetic Condition:
New - New Old Stock - Sealed Box Never Opened, Factory Sealed.

Included:
Everything like when it arrived new

Packing:
Original Manufacturers Packing

Specs:
Power Output Per Channel
100 watts into 4 ohm loads minimum sine wave continuous average power output per channel both channels operating.

Output Load Impedance
4 ohms

Rated Power Band
20 Hz to 20,000 Hz

Dynamic Headroom
2.4 dB

Frequency Response
+0, -0.5 dB from 20 Hz to 20,000 Hz

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 20 Hz to 20,000 Hz.

Signal To Noise Ratio
110 dB below rated output, Power Amplifier
100 dB below rated output, Preamplifier

Sensitivity
250mV for 2.5V rated output, Preamplifier inputs
2.5V for rated output, Power Amplifier

Preamplifier Maximum Voltage Output
8V from 20Hz to 20,000Hz

Preamplifier Maximum Input Signal
10V

Damping Factor
Greater than 40

Power Requirements
120 Volts, 50/60Hz at 3.6 amps

Dimensions
Front Panel: 17/1/2 inches (44.5cm) wide, 5-3/8 inches (13.7cm) high. Depth behind front mounting panel is 18 1/8 inches (46cm) including clearance for connectors. Panel clearance required in front of mounting panel is 1-1/8 inches (2.9cm).

Weight
41 pounds (18.6Kg) net, 60 pounds (27.2Kg) in shipping carton

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 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.