For sale is a beautifully restored McIntosh MC250 stereo power amplifier. This unit was meticulously restored last year by Solid State Audio in New Orleans, Louisiana. No expense was spared and a lot of time and love was invested in making this the best updated MC250 you are ever likely to find. Full details of the restoration are listed out below. I bought this a few months ago out of curiosity, already having an MC240 and an MC225 here to run it along side. I just wanted to see what an early solid state amp can do and this one did not disappoint. It’s a great sounding amp, and I liked its presentation a lot; nicely detailed and live sounding, but not cold or clinical. It sounds great, just not quite as nice for me as the older tube units, so this is one is moving on. There are some light scratches and some small signs of wear, it’s 50 years old now after all, but it presents like a new amp in my opinion. The MC250 is packed well in a heavy duty box and will ship securely at buyer’s expense, but local pickup and demo in the Washington DC area is always preferred. Payment via PayPal friends and family or cash in person. As always, thanks for looking and questions welcomed.
Below is Solid State Audio’s description of their full restoration: “1. Full electrolytic capacitor replacement using the best Vishay Axial capacitors that conserve the original board design
2. Any electrolytic capacitor rated at 10uf or less, has been upgraded with Wima film capacitors.
3. Every single transistor including main output, drivers, etc. has been replaced with modern Onsemi high quality replacements and Hfe matched. All heatsinks were cleaned and new thermal paste and mica insulators installed.
4. The old tired power supply board has been completely rebuilt from scratch! We used a CNC Machine to custom design a turret board of higher quality and match original footprint. The turret board is the same kind we use in our tube designs it has been laced with 16 gauge all copper bus wire, every component on the board was replaced. All resistors were replaced with higher wattage metal film precision resistors, all diodes including main rectifier diodes were replace with fast acting soft recovery ones. The ceramic capacitors were replaced with new higher voltage multi-layer ones.
5. Every single component on the left and right Amp boards have been replaced this includes resistors, capacitors, transistors etc. they have been upgraded utilizing the absolute best components for each specific section chosen not only for reliability but with best sound in mind.
6. Main filter caps were ordered directly from Mcintosh labs these are the same they use for their repairs. Dimensions And mounting are the same as originals so they preserve the original look of the mc250
7. The two other top chassis flange mount caps which include a multisection and single section cap were replaced with custom made caps that preserve the original look and flange installation of the originals these new caps are housed inside an all-stainless-steel enclosure.
8. Every single component on the input board has been replaced with reliability and sound in mind. All the resistors were replaced with special order Japanese Takman boutique carbon film resistors to preserve the warm sound of the amp, all transistors, film electrolytic and ceramic capacitors were replaced. Transistors were replaced with matched Onsemi low noise ones they were matched on a high-end Tektronix curve tracer.
9. Original gain pots were replaced with authentic replacements ordered from Mcintosh labs these new pots were treated with deoxit gold for contact preservation.
10. Original Rca Jacks were replaced with gold plated Cardas audio jacks
11. All signal wire from gain pots, stereo mono switch, and the input boards input and output to amp connections has been replaced with shielded low noise Mogami wire featuring oxygen free copper conductor.
12. Stereo mono switch has been completely taken apart and cleaned to like new condition and treated with deoxit gold for contact preservation.
13. Heatsink cage and bottom cover were completely sand blasted and powder coated with satin black to match original paint. Hardware was replaced with stainless steel screws.
14. Chrome chassis was hand polished and cleaned and treated with chrome protectant.
15. All audio path solder work was performed with Cardas silver audio solder.
16. All functions tested on bench and under load for a period of 24 hours.
17. Power test was performed with an eight-ohm dummy load and a continuous 1khz sine wave both generated and then analyzed out of the amp by a professional state of the art ultra-low noise audio analyzer. both channels were checked at factory rated power and beyond at about 50 watts per channel Analyzer reports a THD of about 0.09% for both channels quite impressive and is an improvement over Mcintosh Factory published specs
18. Unit has been tested for a period of 7 days full rotation under real world listening with several different speaker loads.
19. A set of gold-plated spade to banana jack adapter has been installed on speaker terminals and will be included with the amp these are removable with a screwdriver if new owner wishes to go to the factory terminal strip
20. Adjustments and measurements were done with calibrated Agilent, Fluke, Audio Precision, Sound Technology and Sencore measurement instruments, Tektronix and Siglent oscilloscopes and high end ultra-low noise highly accurate Audio Analyzer among other professional audio repair tools.
Final Notes:
Once the Device has Passed all Rigorous Lab stress testing, it undergoes a full 7-day audition in our listening room under real world use! its connected to multiple sources and speakers of varying loads and design. Once a device performs as well as it sounds it is deemed comprehensively restored. The impact of all the high-quality modern replacement parts and audio grade capacitors combined with the now completely rebuild from scratch power supply and amp sections has let the original amp design really shine!
We'll say it again Mcintosh power amplifiers are legendary this complete comprehensive restoration and upgrade has allowed the original genius electronic design from the masters at Mcintosh sound and perform better when it left the assembly line in the early 70s, we have tested and paired this amp with many of our reference preamps solid state and tube and sounds incredible. the Mcintosh audio transformers made this amp sound absolutely lovely with any speaker type and load we used.
We'll end this long description by saying it has been a privilege to have been able to restore this mc250 and bring it to up to spec with the best components possible it has the sounds and looks that have established Mcintosh into not only a HI-FI legend but also an American icon.”
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