McIntosh MC2300 Solid State Amplifier - Restored and Upgraded

$0

General:

This amplifier is so significant that it has its own Wikipedia page:
The MC-2300 is a solid-state power amplifier which was built by the American high-end audio company McIntosh, and sold between the years 1971 and 1980. It can be utilized either as a 300-watt-per-channel stereo amp, or a 600-watt monoblock, and was rated by its manufacturer as being able to produce this amount of power continuously, with very little (less than 0.25%) distortion. McIntosh's ratings were conservative, however, because like many of their amplifiers, when bench-tested the MC-2300 has frequently been found to produce an even higher level of clean power.

As such, it was ideal for use in demanding, professional applications. Most famously, the improvisational rock band the Grateful Dead employed 48 McIntosh MC-2300 amps as the main power source for their enormous public-address system, the Wall of Sound. Designed by Owsley "Bear" Stanley and others, this system utilized more than 26,000 watts of continuous power fed into JBL and Electrovoice speakers, and was renowned for its natural, low-distortion stereo sound which carried for 600 feet without significant degradation. The Wall of Sound was only in use from March to October 1974.”

We’ve had a few of these in the past - but this one is among the best.

Plus this MC2300 was restored in-house.

This particular piece is in perfect working condition and is in excellent cosmetic condition. It was tested on our test bench to its full rated power and passed with flying colors. All bulbs work, and both meters are responsive. 

The top cover which usually suffers from oxidation is rust free and the stencils are intact. The meters are clean and clear, and the faceplate is also perfect.  I doubt there is another unit out there in this condition and the price we've listed reflects this.  

It's finished in a light champagne color with black paint. Includes a power cord.

Please note this weighs 128 lbs. and will require two people to successfully unbox and set into place. 

SkyFi Restoration Notes:
• Cleaned and detailed entire unit.
• Cleaned controls, Right/Mono Gain control "rebuilt".
• Rebuilt both driver cards:
*All transistors replaced except for the TO66 package device.
*All electrolytic caps replaced.
*Service bulletin mods installed.

Recapped input board:
* All electorlytics replaced.
* Tantalums and tropical fish caps replaced with WIMA MKP stacked Polypropylene film.

• Recapped meter board.
• Cool white LED's added to both VU meters for proper color match from incandescent to LED.
• Converter plug added to allow direct IEC cord connection.
• RCA jacks replaced with gold plated Tiffany parts.
• Tested to rated power (300W into 8 Ohms both channels driven)/
• Calibrated meters to 0dB at 300W, tracking very good in all ranges/
• One of the tests we preformed was running the amp for 10 minutes at 75W to test the fan circuit. Fans activate properly as temp increases and run quiet.

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. 

McIntosh is known for offering distinguished home audio systems that deliver the ultimate experience in music and film. Offering products for two-channel stereo sound systems and multi-channel home theaters with surround sound, McIntosh continues to define the ultimate home audio entertainment experience for discriminating listeners around the world. Our iconic blue Watt output meter is globally recognized as a symbol of quality home audio. With a McIntosh home stereo system or home theater, listeners have the ability to create their own luxury audio experience – and truly live their music.

Ownership:

Single Owner

Connections:

Speaker terminals and RC Input Jacks.

General Sound:

Smooth, uncolored, undistorted, natural and clean.

Cosmetic Condition:

7 - Some Wear and Light Scratches

https://skyfiaudio.com/pages/our-testing-process

SkyFi Cosmetic Notes:
• Light marking around meter bezels.
Some nicks to the faceplate especially around the top left corner.
The RCA jacks are a bit small in diameter. It is recommended that tight RCA interconnects are used for best performance.
One terminal block has one separator fin broken.

Working Condition:

Working perfectly and tested in our lab.

Included:

Just the unit and power cord

Packing:

Will be packed using our highly developed in-house process and custom packing materials. 

Original MSRP:

$1,799.00

Dimensions:

19" rack mounting Width, 10-1/2" Height and 17" Depth.

Weight:

128 lbs unit. 143 lbs shipped.

Age:

1975

Reviews:

https://www.youtube.com/watch?v=MM3bWQg3epo

Link to Manual:

http://www.tubebooks.org/file_downloads/McIntosh/MC2300_%20Owner.pdf

Recommended Cables:

Kimber Kable - RCA Interconnects - Better

Kimber Kable - RCA Interconnects - 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

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 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."

Specs:

ELECTRICAL: 300w/ch. (600w mono). Response 20-20kHz (+0 -0.5dB). Distortion 0.25%. Noise and hum -90dB. Output impedance 0.5, 1, 2, 4, 8 and 16 ohms. (0.25, 0.5, 1, 2, 4 and 8 ohms in mono). Damping factor 14 or greater. Input impedance 200k. Input sensitivity 0.5v. Sentry Monitor.

FRONT PANEL: Anodized gold and black panel. Power level (meters read +3 at 300w). Gain controls. Meter range sw: -20, -10, 0, and off. Power sw: on or off. Handles.

BACK PANEL: Output barrier strips. Audio inputs. Mode sw: stereo or mono. Circuit breaker. Dual cooling fans.

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