twiiii
Lunatic Member
Now the Question brought up by autoformers. Yes, they provide a great function. The serve to center the speakers impedance curve to the output transistors best performance. It allows Mac to use fewer output transistors, smaller heat sinks, and a smaller power supply to drive loads less than ideal. Remember a 7200 could drive 2 ohm loads with very low distortion and high current at levels close to 500 watts and 1 ohm loads, too with out autoformers. But as Davie O. asked, "AT what cost!" It wasn't until the generation of the MC 501 that could drive 4 ohm and two loads from the 8 ohm tap that autoformers came into their rightful place still meeting specs, The 2205 2105 2255 etc if asked to drive complex ported or speakers with high ordered crossovers where rated at 8 ohms were actually closer to 3 ohms, were in big trouble. Some folks will tell you even today because of the complex impedances of a XRT 1k they should be driven from the 4 ohm tap rather than 8. Fully balancing the amps has helped,too and the new thermal tracking devices keeps distortion down with these mismatched loads, science goes forward and the sound gets better, We hope!