TECHNICAL DATA
When buying a stereo system, it's not recommended to decide
what to buy according to technical data.
A stereo system should give the listener enjoyment of
listening to
music - and there are no technical data that show how
"musical"
a system is.
There is no way to describe a music played by an orchestra
in a
mathematical way (although there were several attempts
to do it)
and there is no way to describe the ability of a stereo
system to
"pronounce" musical quality and technical data
say nothing
about it.
One of the features buyers love to check is the power
of amplifiers.
The way manufacturers measure output power of an
amplifier, is
exactly (believe me it's true) the same way other manufacturers
measure
the output power of a heating oven. and exactly as the
power of
an oven says nothing about it's musical quality, a power
output of
an amplifier says nothing about it's musical quality
too.
You must distrust people who try to convince you about
stereo
system according to it's technical data. Even if a person
is an
engineer, even if he can tell in details how the signal
goes from
input to speakers, don't buy it. It's better to consider
a stereo
quality by listening to a musical annotator then to an
engineer.
Few words about output power (to prove why to ignore technical
data ) -
1 - Our ears react to level of sounds in a logarithmic
way. It
means that a 100 watts amplifier
can be only twice
as loud as a 10 watts amplifier
to our ears.
Bear in mind that at home several
watts per speaker is very
loud (unless your living room
is huge ).
2 - The real data that pronounces the power of an amplifier
is the ability to supply current
to various impedance for
given periods of time (very
short periods). This definition
comes because of the character
of the speakers.
A speaker has an impedance that
gives varying resistance
to current depending on current
frequency. The current
frequency varies from 20 Hz
to 20,000 Hz - and it
defines the speaker resistance
from 2 to 16 Ohms (better
speakers give less range of
resistance).
The amplifier deals with very
quick signals with quick
transitions from peaks to zero
in milli seconds. This
signals have a very complicated
structure and have nothing
to do with the structure of
signals (simple sinus) used to
measure power output.
An amplifier that can supply
a given current to a RANGE of
resistance for a given period
of time (3 milliseconds at least)
has more power than -
An amplifier than can supply less current for the same period
to the same range of resistance.
Or
An amplifier that can supply the same current to a shorter period
of time to the same range of resistance.
Or
An amplifier that can supply the same current to the same period
of time to a smaller range of resistance.
Notice that an amplifier that rates
with 1,000 watts to 8 Ohms, if it
connected to a speaker that gives
a resistance of three Ohms refer to
several frequencies, if the amplifier
can't supply current on that
resistance, the power of the amplifier
at these given frequencies is ZERO
no matter what are the other features
of the amplifier.
Did you ever see a dealer that compares these data ?
So talking about power, like all other
features, the judge is
OUR hearing system at OUR HOME !