| Some thoughts about home stereo systems | |
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Report by Stefan Spännare, November 2006, updated August 2007 and June 2009
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I have actually not seen a definition of an ideal amplifier, but something
like this could fit:
An ideal amplifier is completely linear over the whole observed frequency
range without adding noise or distortion to the signal.
This statement is also valid for a complete stereo or electronic music system
including speakers, CD player etc.
Of course such an "ideal music system" does not exist, but it is possible
to come close.
Here I am talking about the "ideal music system" that should be the goal
for all stereo and electronic music systems. I am well aware that music and
listen to music is something very subjective. The needs are also different
depending on the environment and what kind of music is played. Here are
presented some of my personal opinions and thoughts.
Each music artist or composer certainly has a special idea about the sound
of his or her music. In the music studio this sound should be kept and stored
on the media (CD, DVD, LP, tape etc). Of course no one has an ideal stereo or
music recorder but studio equipment can be supposed to be very good. The only
task for a good home stereo is to play the music exactly as it was meant to
be and recorded. Therefore at least I do not like music systems where it is
possible to adjust the sound of the music in different ways. I.e. treble and
bass adjustment, equalizers, digital manipulations etc. For example MP3-players
can be very good, but in principle I prefer uncompressed music formats.
According to my (and many others) opinion the speakers are the most critical
components of a stereo system. Any good amplifier can do the job, but the
speakers set their personality to the sound. If you are a music epicure
perhaps your goal is to choose a stereo system and speakers that come
as close as possible to the "ideal music system".
On the other hand, one thing that is often forgotten is the benefits and
limitations of the human ears and that their performance is degraded with
age. A good Hi-Fi system probably perform better than what your ears can
perceive. So when you are going to buy your new stereo system in the Hi-Fi
shop listen to your ears and heart and choose a system with a sound that
you really like and fit your needs. I must not necessarily be an "ideal music
system". Good stereo systems are also quite expensive which of course
is a limitation for many people.
The properties of the room where the music is played is also very important.
A bare room with echoes affects the acoustics negative. Some soft things in
the room, such as curtains, a large carpet, a cosy sofa and some pictures
on the walls usually improves the sound experience. Large rooms are also
better than small.
There is a somewhat hysteric trend that amplifiers and speakers must have as
many Watts as possible. According to my experiences 15 W (rms) per speaker
is a quite high volume in a normal living room. On the other hand the amplifier
and speakers should have some "over capacity" to not work strained.
Many people claim that a gramophone with LPs is better than a CD player.
This is probably true for a very good, expensive and well adjusted gramophone
and LPs in good shape. However for the average user, that is not an expert,
a good CD player usually perform better and is much more simple to use.
I must also say a few words about tube (or valve) amplifiers. Many experts
claim that such amplifiers are superior to anything else (i.e. transistor and
MOSFET amplifiers etc). One is talking about the "valve sound". Other people
mean that the sound is good but "different". But it is easy to imagine that
a good class A tube amplifier is something very special. Actually I have a
dream to once build such an amplifier. However, tube amplifiers also have
some disadvantages. They are expensive to buy, have high power consumption
and the tubes have to be replaced now and then when they are aging. This
makes them quite expensive to use.
Modern transistor amplifiers of good quality are usually very robust and can
be used for many years or perhaps decades. The weakest components in such
amplifiers are the main electrolytic capacitors in the power supply. They are
aging depending on temperature an load. When the capacity degrades the
sound of the amplifier will be worse. Therefore it can be wise to replace the
capacitors with new ones say every fifth year or so. With some effort it is
quite easily done with construction kit amplifiers, but it can be somewhat
more difficult and expensive to do with commercial amplifiers.
Electro-mechanical parts of the amplifiers can also be sensitive. After some
time of use there can for example be loose contact in the volume, treble and
bass potentiometers with noisy sound as result. These parts can be somewhat
tricky and expensive to replace especially in commercial amplifiers. You can
also try to spray the potentiometers, contacts and switches with electronics
spray. One good is "Multi Spray PRF 5-99". It is very effective and cleans,
lubricants and deoxidizes very well. However, it can be difficult to get and
is not so environmental friendly.