Older McIntosh Tube amps - a word of caution


Occasionally one sees MC225s, 30s, 275s etc coming up for sale. A year ago I purchased a 225. Supposedly working. Yeh right in what decade. The inside was scorched and the seller and I settled on a partial refund.
I spent 100 hours replacing every part inside but the choke. I had called around but no one will touch a complete rebuild. Somewhere around hour 90 it dawned on me why. Very high risk. In the end the amp has a new chrome chassis, new powder coat, iec connector, chrome push button power switch, all Takman metal films, Solen supreme caps for films, tantalum cap on input, new raised twisted heater wiring harness, screws that look like rivots, ok you get the point very little original.
My point of writing this is that you see these up for sale now and then. A few will have a some to all capacitors replaced. I have had a McinItosh representative that is very familiar with the old tube amps have a listen. He asked me what about the rebuild. I told him what I did as well as how I lowered the frequency response. He thought a minute and agreed with all the changes. Then he said something that bears repeating. "You have done the right thing. All these amps need a full rebuild before being used".
So while I sit here enjoying this little gem as many have done, I thought I should pass this on. My "old man" as I call him has a couple hundred hours on the rebuild. There is no lack of bass. Dynamics are fast and the sound stage is deep and expansive.
If you choose to purchase such an amp. Read the forums. Take pictures and mark part values on the pictures. Mark every wire. Work methodically one section at a time. Learn how to remove rivots. Be oh so gentle and you have a chance at succeeding. But as the Mcintosh rep said, don't power it it up without a rebuild. Those transformers can't be replaced. You blow one and it is game over.
ajcrocker1
Those transformers can't be replaced. You blow one and it is game over.

As far as I know, if sent to Mercury Magnetics, they will remanufacture transformers or build an equivalent. Their transformers known to be very good for any tube amp project.
Thanks for the post.
You make a good point.
Possible purchasers should consider this unless their purpose is to rebuild for the fun of it ;-)!
Anyone buying vintage gear should assume that they will need work. Unless you buy a completely rebuilt unit from someone like Mapleshade. Now you see why they charge so much___
Better spend the 're build' time listening to music, for it is that which audio is all about. Also, why do what others have done, that being copied the Mc design into units with all state of the art components. Who does that? Cayin. Check them out at cayinusa. I have a few of their products, including a knock off of the HK Citation I pre amp. Could not be more pleased. Great sound, great value.
Heyboer can rewind those transformers.

All I get from this is that you bought a bad amp. Nice Macs, like most
vintage tube gear, just need the power supply rebuilt, the coupling caps
changed, any out-of-spec resistors replaced, and they will be good for
another 50 years or so.