1970's, 80's and 90's Japanese speakers are mostly trash. Very few are good 

This is why i am not a big fan of old (vintage) Japanese speakers.
They are weak, they sound terrible, and the quality is just not there.
Now is there exceptions? Sure, there are a few models from a few brands that sounds good, and have good quality, but for the most part, it is a load of crap.
Have you ever wondered why European and USA made speakers sold better in Japan in the 70's and 80's than their own brands? Well the simple fact of build quality and sound quality was way better.