ZERO OHM COIL

Crossover Network Tuning
Our experience shows that high-quality crossover network components can get between 30% and 50%
more performance out of your speakers! Good crossovers don't cost all that much and they deliver radical
improvements, even in low-cost configurations. This was graphically demonstrated in a report in the
leading German hi-fi mag Klang & Ton (see quote below). In the "cheap trick" described in the K&T
article (154€ for the speaker pair) the great enhancement in listening pleasure provided by using highend
crossover components easily justified the additional cost of 77€, which is just one third of the
total final cost of the speakers. It would be difficult to find a better illustration of the crucial importance
and huge benefits of high-grade crossover components:
("The replacement...brought a really striking improvement in quality, particularly in mid range, high
range and overall presence. The new sound is completely natural, without any trace of 'loudspeaker'.
It's as though there were no more speakers you could identify as the source of the sound - what you
hear appears impressively disconnected from the physical speakers. Everyone who listened to the
results agreed that the enhancement to the sound fully justified the additional DM150 for two highend
crossovers.")
("In the high-end version the second capacitor in the crossover is a MKP metallised paper model
(C1, in parallel to the woofer). This component delivers a very perceptible improvement in the mid
range over the inexpensive electrolytic capacitor, demonstrating that even the parallel components in
a crossover have a real and significant influence on the sound.") Klang & Ton 4/98, p. 64 ff.
Having read this you're probably interested in the details of "our" recipe for tuning a crossover network for
optimum sound performance
• Air is by far the best coil core material. Use air coils wherever possible. But remember, when
you replace coils the new air coils must have the same low resistance (W rating) as the existing
(cored) coils. This is crucial!
• There's no alternative to coils with cores for applications calling for very high inductance values.
When you have no choice, coils with Aronit cores are definitely preferable to ferrite, provided
that their internal resistance is low enough.
• On the other hand, ferrite core coils are easier to install in cars than coils with Aronit cores.
• In the deep bass range there is ultimately no real alternative to transformer core coils and zero
resistance coils. They are the only designs that enable you to combine extremely high
inductance values with low resistance and exceptional power handling capacity.
• However, reducing the internal resistance of the bass coil is not always advisable as this also
changes the tuning of the system. As a basic rule of thumb you should only make this change if
you want to change the bass tuning, making the basses more "dry and precise". It's important to
understand that "dry" in this context also means "less" bass!
• All coils, including the coils wired in parallel to the speaker unit, should have baked varnish
windings (or vacuum impregnated windings with wire over 1.4mm thick).
• Install an MCAP Supreme directly upstream from the tweeter. This generally makes the sound
enormously more spatial and transparent.
• When very high capacitance is called for, for example in two-way configurations with a low
crossover frequency, you can save money by connecting an MCAP Supreme and an MCAP in
parallel. (The Supreme should contribute at least 30% to the total rating.)
• Mid-range: Connect an MCAP in series to the speaker unit.
• If possible, all parallel capacitors should be MCAPs, or at least MKT metallised plastic film
capacitors.
• At a pinch you can also use film capacitors and electrolytic capacitors connected in parallel for
the bass range.
• All resistors in the signal path and parallel to the tweeter should be metal oxide components.
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