Mosfet mist?


Greetings,

I have read several articles on the sonics of mosfet amps to include Adcom,B&K,Counterpoint,Perreaux,etc. What exactly is mosfet mist and how would one know what to listen for. Are some amps more prone to this mist than others? I have a Perreaux 1150B doing woofer duty on a pair of Focal 706s spkrs(A modified Parasound 1000A on top)How would say the 1150B compare with a B&K in relation. Thanks.
south43

Showing 3 responses by atmasphere

Mustagefan, yes. This was more of a problem during the lateral MOSFET period. These days you see more of the vertical MOSFETs. I think what has happened is that in the old days designers did not always take the input capacitance of the devices into account. Experience is always helpful though so the issue is less common with modern designs.
The 'MOSFET mist' is a term coined that points to the problems of driving extremely capacitive inputs of the output devices of a MOSFET-based amplifier. If the driver circuitry lacks the current to deal with this capacitance, there will be a high frequency roll-off, hence the term.
I've been studying that very question for the last year or so. There are advantages to each, but in my case I think I would go with the MOSFETs for the additional linearity- I like to run things zero feedback.