McIntosh MC240 Vintage Tube Amplifier - Restored and Sounding Amazing

Free Shipping on *ALL* Electronics (Excluding Speakers, Contiguous 48 US States Only)

These low power vintage tube amps, along with the MC225, are among the best sounding out there and perfect for powering your vintage or high efficiency speakers. If you have modern speakers capable of bi-wire, we find these to be fabulous at powering the mids/highs like a recent custom JBL 4-way system build for one of our clients.

When restoring the 240, we often replace the chassis with a stainless version since they're usually rusted or show some pitting at 60 years old. That was NOT the case on this one.

It arrived with a gorgeous chassis and great paintwork on the transformers, so we decided to leave it alone on the outside. The inside, as you can see from the notes bellow, was fully addressed making this piece super reliable and safe to use for a several more decades.

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

Countless hours go into properly restoring one of these amps along with a plethora of carefully selected high quality parts, so it is therefore priced accordingly.

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 McIntosh official service manual, including the feedback and phase splitter balance networks. 

A fresh set of tubes was specially selected for this unit. It consists of a mix of modern production and vintage tubes, which were carefully tested and matched using our professional and modern 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 Amplifiers (Tube):

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 calibrated B&K 747 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.