Yamaha MX-55 topology, any good ?

[SirPaulGerman]

I was able to get a Yamaha MX-55, that the previous owner recently recapped it.
Is the MX-55 any good ? what type class is it ?

it was a expensive amp when it was released

https://audio-heritage.jp/YAMAHA/amp/mx-55.html


Here is the service manual and the numbers for distortion after refurbishment

 

[EdGr]

I see an op-amp input and a conventional class AB output.

It may have been expensive because it is four amplifiers (bridged in 2-channel mode). This avoids high-voltage transistors.

I would say that it is competent engineering without aspiring to greatness.
Ed

 

[SirPaulGerman]

What about the specs ? Are those any good ?
Are all the MX Yamaha share the same topology?

 

[EdGr]

Each amplifier outputs 35W. It needs bridging to do 70W. These numbers are quite low today.

The distortion measurements look good because of high negative feedback.

I know only about what you have posted. 😉
Ed