McIntosh MC240 Tube Amplifier - Vintage Beauty - FULL Restoration

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We painstakingly restored this classic and coveted stereo tube amplifier to its full glory, including a new stainless chassis.

Internally we replaced every critical component while carefully maintaining the original sonic quality.

This listing also includes a rare and correct McIntosh tube cover, plus a matched set of 6L6GC tubes in the output stage. 

This is a 40W x 2 (stereo) tube amplifier produced from 1960-1969.

Countless hours and hundreds of dollars in parts went into this restoration - its working perfectly like the day it left the factory if not better.

It will ship in a custom made double box for safe transport.

Restoration Notes:

This MC240 underwent an extensive electronic restoration. The power supply was completely rebuilt with modern production multi-section electrolytics. All power supply resistors and diodes were replaced. The bias supply selenium rectifier was changed to silicon and properly compensated to provide perfect bias for the output tubes. 

We also upgraded all of the aging paper signal path capacitors with audio grade polypropylene film caps. 

The majority of the carbon composition resistors were changed to high precision metal film. Special care was taken to match resistor values in key sections indicated in the service manual, including the feedback and phase splitter balance networks. 

A fresh set of tubes was specially selected for this unit. Consisting of a mix of modern production and vintage tubes which were carefully tested and matched using our modern professional Amplitrex AT-1000 tube tester.

McIntosh MC240 Original Sales Brochure

McIntosh MC240 Owners Manual

McIntosh MC240 Schematic and Parts List

McIntosh MC240 Maintenance Manual

The SkyFi Testing Process for Tube Amplifiers:

We start with a visual inspection of all internal components to make sure there are no signs of stress or aging. Capacitors are checked for telltale sings of bulging or leaking, resistors are checked for signs of overheating or cracking, and tubes are inspected for signs of stress overheating or cracking.

We then power up the unit carefully and run a simple 1k sine wave while monitoring the output on an oscilloscope for signs of distortion or noise. Finally we run the amplifier to its full rated power into the appropriate resistive load provided by our Sencore amplifier tester. If there is an issue, it will usually be noticeable at this point. If it all looks clean we will often test for THD (Total Harmonic Distortion) measured by our Keithley distortion meter, and compare it against the original manufacturers specifications. The amplifier the remains powered on to "burn in" on our test bench for a few hours to make sure there are no heat related issues. If there are balanced inputs available they will also be tested.

We also test all tubes for output gain and leakage on our modern professional Amplitrex AT-1000 tube tester against the original manufacturers specifications. If needed, the tubes will be replaced from our vast NOS (New Old Stock) vintage or modern inventory.

Final testing involves pushing actual music thorough the amplifier. We've learned over time that some issues are only noticeable to a trained ear while listening to familiar source material. Our test bench has reference vintage KEF speakers that we're very familiar with which quickly reveal any discrepancies. Some amplifiers will then move into our listening room where they are tested with our in-house reference speakers of choice.

Please click here for detailed specifics regarding our specialized packing process that separates us from the rest.