JAC MUSIC GM70 DUAL MONO BLOCK AMPLIFIERS WITH SAKUMA AND PARAFEED PRINCIPLE


"The Japanese Designer SAKUMA, is famous for driving transmitter tubes like 845 or 211 with the same tube, to cancel harmonics. Mr. Susumu Sakuma has published this method in Japan in the 1980's, and later in Sound Practices in 1997. Another method to reduce distortion is generate the required Error signal with dedicated electronics, and then it is called compensation. Compensation is more complicated, but then you don't have the disadvantages of negative feedback. The method of Mr. Sakuma is a very effective way with compensation. The theory is also explained in a German book by Rainer zur Linde †, called "Verstaerker in Roehrentechnik", ISBN Number 3-928051-02-4, and you find it on page 45."

Link: here.