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Fustica bron voor condensatoren en Vintage audiocomponenten |
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The
best capacitor is… |
no
capacitor! |
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What
is a capacitor? The
capacitor is one of the oldest electronic components. Electrical
conductors where discovered in 1729. In 1745 the Leyden jar, the first
capacitor, was discovered by Ewald Georg von Kleist, a German inventor. A
Dutch physicist, Peter van Musschenbroek of the Currently,
the Leyden jar is a glass jar with a metal foil coating on the inside and
outside. The
capacitor serves as a means of storing electricity, and the greater its
capacity the more electricity will it store. The capacity depends on the
size of the plates opposite to each other, the distance between the plates
and the nature of the insulator between them. |
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Capacitors
as used in audio amplifiers There
are several types of capacitors (caps), such as the conventional capacitor
with metal foils for both plates and impregnated paper between them. Even
today there are Metallized Paper (MP) capacitors, also called paper/oil
capacitors available. Later
Mylar (Polyester) and other synthetic diëlectrics
(isolators) became more common.
In the sixties, the
metallized Mylar cap became very popular. The two strongest points of those
caps are there smaller size and the fact that they are self-healing.
Today they are used
in almost every electronic device. Because of the huge quantities that are
manufactured of this kind of cap, they are rather cheap. An
other kind of capacitor is the electrolytic capacitor. This is a very special
cap with mostly high to very high values, starting by around 1µF to several
ten thousands of µF.
In tube amps are
values from 4 to 220 µF most common. They are mainly used for decoupling or
for filtering in the power supply. Electrolytic capacitors will not be used as
coupling caps in tube amps, also not in good Quality transistor amps. The
most common coupling caps in middle of the road amps are metallized Mylar or
Polyester caps (MKT). In higher Quality amps mostly metallized Polypropylene
will be used (MKP). A
mostly forgotten type of capacitor is the metallized Polycarbonate type (MKC).
Especially the MKC types from ERO are very famous. Particular because they
have a very balanced, musical sound with very little coloration. However MKP
types have a brighter sound, they have mostly more coloration too. An
other rather unknown type is the MKV capacitor, this is a metallized
Polypropylene capacitor in oil. It has better specifications than metallized
Paper (in oil). Even
by the today commonly used MKP capacitors, there are differences between
different brands. Of course there are very exotic capacitors with very little
coloration, but they have also very exotic prices. Except
the common metallized types there are also not metallized
types, a good example is the Styroflex or Polystyrene capacitor. Mostly they
are limited to values of about 0.1 µF, because they are much larger as
metallized types. A
many times forgotten aspect of a decoupling capacitor is, that it is in the
signal way! A
perfect capacitor should have an impedance of zero Ohms from DC to
light-frequency. But there exists no perfect capacitor ...! * The
intention of this article will be that every (de-) coupling capacitor in an
audio amplifier has its own particular "sound". It is also possible
to use transformers as a coupling element instead of
capacitors, such as interstage and balanced input or line output transformers.
If you use a good Quality, you will be surprised by the audible results! *** |
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"Tubes are for Music, transistors are for TV and electronics in general" |
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