My wife bought me this McIntosh MA-230 integrated hybrid tube amp. A very cool piece. and sounds good to. This was the first hybrid integrated amp produced, Has a solid state pre-amp with a tube power amp section. The power tubes are 7591, the smaller tubes are 2, 12ax7 and 1 12au7. The smaller tubes are Telefunken's.
I spent 4 hours on this, cleaning all the controls, and polishing the chassis and faceplate. Checking capacitors, and everything out. It is now working good. I do think the power tubes are at the end of there lifespan. I also have the wood case, it is undergoing some repairs. A couple of deep scrapes, and a small crack.
This sound real good the way it is, but I think I will do a total restoration after we get moved. It was after all, built way back in the 60's. I think they were produced from 63-66.
If anyone has a good quad of 7591 power tubes, let me know.
Here are a few pics.
