McIntosh MC225 Vintage Tube Amplifier - FULLY RESTORED

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Many audiophiles hail the MC225 as the best sounding vintage tube amp from McIntosh. Especially if you have high efficiency speakers.

We totally agree that if you don't need the extra 40W or 50W from the MC240 or MC275 then this is the best piece. However, don't be fooled into thinking an unrestored eBey special will perform to that level.

This MC225 just underwent a full in-house electronic restoration.

The power supply was rebuilt with quality reproduction multi-section can capacitors and NOS carbon comp resistors.

The bias supply was also rebuilt with the proper compensating resistor for the perfect bias level - a necessary step after switching the rectification medium from Selenium to Silicon.

The MC225 features very high quality dog-bone dipped film caps for the majority of the circuit which tend to hold up extremely well over time. There were only six original paper caps that needed replacement. These were swapped to modern production polypropylene components. The first stage cathode bypass capacitors were replaced as well.

All carbon composition resistors were checked and confirmed within acceptable tolerance. There are 8 resistors in this circuit that require precise adherence to the schematic value. All 8 are within 1% of target value.

This example has cosmetic blemishes consistent with age: light chrome rust, marks and dings on the transformers, and some silk screen lettering wear.

We compare this item to a tastefully restored vintage car - think all parts replaced to keep it reliable and on the road but keeping its original history and character.

Tube Notes:
• 12AX7 - Tested Pre-Owned Japan (Balanced Triodes)
• 12AU7 - NOS RCA Cleat Top Side Getter (Matched and Balanced)
• 12BH7 - Tested Pre-Owned GE (Balanced Triodes)
• 7591 - New Current Production Tong Sol Reissue (Matched Quad)

McIntosh MC225 Vintage Tube Amplifier - Owner's Manual

Click below to add our recommended matching cables from Kimber Kable, all brand new as SkyFi is an official Kimber dealer.

Kimber Kable - RCA Interconnects

Kimber Kable - Speaker Cables

Kimber Kable - Bi-Wire Speaker Cables 

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 and calibrated 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.

More from the Original McIntosh Owner's Manual
The MC225 has on one chassis two 25 watt power amplifiers. In addition to use as a stereo amplifier, the flexibility of the MC225 permits it to be used as a monophonic amplifier that delivers 50 watts, or as two separate 25 watt amplifiers with each channel amplifying completely separate pro- grams, or as two amplifiers for use with an electronic crossover network. Such flexibility permits maximum use for greatest return from your investment.

Over one million watts of amplifier output power capacity have been manufactured by Mclntosh since 1947. In this 1,000,000 watts of audio power there are less than 10 watts of distortion capacity and less than 1/100 watt of noise capacity!

The dramatic difference in the quality of music reproduction when you listen through Mclntosh instruments is directly due to low distortion performance. Careful, devoted research is a way of life at Mclntosh. The world's finest amplifier is the creation of per- severing, resourceful Mclntosh engineers. Mclntosh Laboratory is the only manufacturer in the entire industry to guarantee the lowest distortion at all audio frequencies, at full power. The U.S. Patent Office has rec- ognized the advanced technology of the Mclntosh circuit by granting 6 patents.