Mcintosh MC30 Vintage Tube Monoblock Amplifiers - Restored

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With regards to sound quality, the MC30 is considered to be the most desirable McIntosh model among audiophiles and collectors. It was only produced from 1954 to 1962, and unlike other McIntosh Tube amps there were no later model anniversary or commemorative editions produced.

The restoration goal for this pair was to make these classics as reliable and as cosmetically clean as possible, without disturbing their special vintage sound quality.

SkyFi Restoration Notes:
• New and professional reproduction chrome chassis.
• Multi-section filter can replaced, and new power resistors installed for the B+ Supply.
• Bias Diode replaced with a silicon unit.
• All signal path capacitors replaced with Solen branded polypropylene.
• Select out-of-spec resistors replaced on the peg boards.
• Bottom cover and transformers appear to have been repainted with textured matte black.
• New high quality RCA connectors.
• New Cinch barrier strips (also called a terminal block) for all speaker connections
• Both pieces have their original power cords but were reduced to 4 feet in length during the restoration for safety/to remove some past damage.

Both MC30's performed amazingly well on our bench tests. They are perfectly balanced to one another. Clipping at just under 35W each into 8 ohms.

Tube Notes:
• Each MC30 is loaded with a carefully hand-selected set of vintage driver and rectifier type tubes. Alongside current production Tung-Sol 6L6GC output tubes.
• All tubes were tested and verified on our modern and professional Amplitrex AT-1000 tube tester.

• V1 - McIntosh 12AX7
• V2 - NOS Philips ECG 6189W (12AU7) 
• V3 - Vintage GE 12BH7
• V4 - McIntosh 12AX7
• Rectifiers - Sovtek 5U4G
• Output Tubes - NEW Plate Current Matched Quad - Current Production Tung-Sol • 6L6GC re-issue

McIntosh MC30 Owners Manual

Please see our photos or the above manual for full technical specifications and dimensions.

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 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.