Amp for the 3.7's: 28B SST2 or MC601? Others?

[Ian]

Originally Posted by mbovaird

Having owned those speakers, I would go with 601's or preferably 1.2kw's. They gobble up power like no other speaker I've ever owned (even more than my current speakers). The Bryston amps are excellent too....but unless your room is small, go for sheer power the 3.7's crave....go for the 1.2kw's. Ivan owns both....maybe he can advise you which is best for the 3.7's.

You run the very real risk of blowing out the ribbons in the 3.7's at high current levels. The aluminum foil ribbons used in Maggies will melt at somewhat lower current densities than equivalent dimensioned copper ribbons (in part because of the higher conductivity of copper). The Maggies are very inefficient because of the low magnetic fields generated across the relatively large air gaps that the ribbons sit in. I measured around 0.1 T (Tesla) across my 20.7 air gap. A good cone speaker can have air gap fields above 1 T. The force (Lorentz force) which moves the ribbon is proportional to this magnetic field and is also proportional to the current flowing in the ribbon (or coil). I have blown ribbon speakers many times over the years by driving them with excessive currents. They are a real pain to repair.