I got this as part of an auction haul... let's find out what we have. Of course if it's messed up, I'd work to fix it, but sometimes life gives you a pat on the back rather than a slap in the mouth.
These are from the mid-late '70s. I bought a Thirty112 in 1977 and it was a brand new model at the time. I seem to recall that the Series II amplifiers (with the Parametric EQ section) were coming out around that time too. The store I bought my Thirty112 from couldn't keep the Fifty112 in stock, they were selling like hotcakes! A year or two after I bought the Thirty, I traded it (at the same store) even up for a genuine, very clean '57 Fender Princeton (tweed). Wish I still had that amp!!!
I actually FORGOT about this amp. It did sell pretty fast after it arrived here. I've had a number of Yamaha amps come through here, and all of them were well made.