Quote Originally Posted by walpurgis View Post
I bought a new F307 from Lasky about 1971. It hummed like mad and had to be returned. The replacement was noisy too, so that also went back and I took a Rotel RA-611 instead. I liked that amp a lot, it was very good. Funny thing is, a few secondhand F307's have since come my way and they've been fine.
Early ones were dodgy in the output transistor area and there was I believe (hopefully Mick will know more) a factory recall to fit more robust output devices and whilst there change a few parts associated with bias regulation.