Even the most novice audio buyer understands
what a watt is... a measure of power, how strong, how loud an
amplifier will play. More watts mean more sound.
But not always...not all watts are created equal.
The Difference Lies in the music. When we test an amplifier we use a standard test
so one test can be compared with the next. That standard test
requires we hook up our amp under test to a precision 8 ohm resistor.
We feed a pure, single frequency test tone into the amp, and
then we measure everything in the speaker outputs that is not
the frequency we fed into the amp under test. That's RMS power.
But, we don't listen to amplifiers with precision 8 ohm resistors,
we listen to speakers which are not 8 ohms, but a combination
of resitors, capacitors, and inductors, which vary with frequency
and loudness.
And music is not made up of one frequency, but all different
frequencies all mixed up. And these frequencies are constantly
changing, not static as used in wattage ratings. The amplifier
tests use
So the standard test is not really a very good test of how loud and clean an amplifier will play.
MOSFETS. Metal Oxide Semiconductor Field Effect Transistors. A mouthful that creates an earful.
There are those who think old fashioned tube amplifiers sound more like music than transistor amps. MOSFETS combine the advantages of both.
MOSFET output transistors are usually found on expensive separate power amps. They use them because they sound more musical.
In a regular bipolar transistors there are two currents (hence the same bipolar) and this slows down the transfer of current through the transistor. Bipolar transistors are sensstive to heat and as you drive them harder they heat up and without eleaborate protection circuits would blow up. These transistors produce odd order distortion wihich is objectionalble to the human ear