On Thu, 18 Sep 2008 20:06:43 -0700, Kevin McMurtrie
wrote:
In article ,
"Arny Krueger" wrote:
"Eeyore" wrote in
message
Kevin McMurtrie wrote:
In article ,
Damon Hill wrote:
RichD wrote in
news:b78fc9c2-fe9c-444c-8ac5-
:
Who do MOSFET sound better than bipolar, as an audio
amp output driver?
They do? Seems like it's possible to design good
amplifiers either way.
--Damon
Exactly - zero difference in quality capabilities. It's
usually a matter of impedance matching. Silicon
transistors have a fixed loss around 0.5 volts. MOSFETs
have a resistive loss inversely proportional to their
voltage rating. That usually makes MOSFETs less
expensive for low impedances and transistors less
expensive for high impedances.
TOTAL AND COMPLETE GARBAGE.
Agreed. Actually, what Kevin said is the exact reverse of generally accepted
practical knowledge. Bipolar is generally more efficient when the impedances
get really low. MOSFETs were trendy for a while, but most new power amp
designs seem to have bipolar outputs.
Time to check the specs for this decade. Visit IRF. You can get a
surface mount MOSFET in package similar to TO-220 that has 0.0008 Ohms
on resistance, 300W dissipation, 24V rating, and a 1600A surge rating.
Now I remember why I left this newsgroup.
IR is famous for creating incredible specs, with tiny footnotes
retracting the wilder numbers. No TO-220 is going to last long at 300
watts; not many milliseconds.
John