Saturday, April 7, 2007

Ebay Madness

About two months ago I ordered a vintage Yamaha amplifier to use for my surrounds in the home theater setup. I ordered it from a vendor with a fantastic rating who did a lot of business with pro audio gear.

It took him a month to get me the amplifier, and when it got here it had a bad relay. Honestly, I should have given him a negative rating, but since it gave me an excuse to open the amp up and do things to it, I only gave him a neutral rating.

Anyway, the point is, because of this, my next project is upgrading a Yamaha P2075.

I've already replaced most of the power supply caps and by-pass caps. I removed the relay, and replaced it with a relay in a socket. 20 years from now when this relay goes bad, it will take some one 3 minutes to replace it. I've also removed and socketed the op-amps with NE5532. Not top of the line anymore, but they were good enough to give the Benchmark DAC-1 a Class A rating from Stereophile. If this amp wasn't just for the surround speakers I might use the latest op amp from National semi, their much lauded LM4562.

Next week I'll be finishing up the capacitor upgrades, including replacing the coupling caps and also replacing cement resistors with top-of-the-line Mills 5 Watts.

By the way, I really really like the Mills resistors for reliability. I accidentally shorted a Tandberg supply with them in it, and it was only when I noticed smoke coming off one that I realised what I had done. That must have been 10 seconds of severe overload. Once I let everything cool off, the Mills resistor measured exactly the same value as it had started with. Because of this, wherever the reliability of a power resistor is in question, I always use a Mills. Plus, they have a great range of values. If I can't use those, I will use a severely over-speced Vishay Metal Film Power (PR02, 03, etc.)

Next time I'll post before and after pics.