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The crossover is the heart of any highend loudspeaker
effort, where enclosure design is done with pure high tech science
and research and development the crossover is as much a dark art
as a science.
The shear number of crossover topologies and iterations within
those topologies that are available to a designer are endless! What
add on circuits to apply when and for what ailment a design has
at its particular stage of development is a task for an ordered
mind.
Let's first talk about the individual components that make up
a crossover.
Inductors.
- They should be Aircored and as large a gauge as the budget and
practicality can allow. Low tension winding double stabilized
in motor winding varnish or ideally boiled and encased in bees
wax. As a general rule of thumb a high-end design effort should
use a bass circuit inductor that weighs at least the same as the
bass driver itself. In the ML1 Signature it's actually heavier
at 1.2 Kilograms for the inductor verses 1.05 Kilograms for the
bass driver.
In fact the factory control crossover bass inductor for this design
weighs double that of the bass driver.
Small gauge inductors reduce the damping available to the bass
driver which in turn reduces the grip or control the amplifier
has over the cone, it can't start and stop without overhang(a
little like a boxer whose glove is connected to his elbow with
a rubber forearm, he couldn't jab with speed or precision ).
All Inductors used by LenehanAudio are wound and toleranced inhouse
by ourselves.
Capacitors.
- A range of capacitors are used in our loudspeakers starting
with Mundorf Mcap in our entry
level models then moving up to Auricap in the Signatures and
finally to the Dueland copper foil caps in the level 2 signature
designs.
Capacitors do make a difference, unfortunately they can be very
expensive!!
Resistors.
- Resistors are very important components! We use only Vishay
high-power wire wounds(5watt to 20watt) with Temperature Coefficients
in the 30ppm to 50ppm range.
Cheap resistors compress dynamic range. Let me explain 10 watt
sand-cast resistors (square bodied white in color) with temperature
coefficients in the 250ppm to 750ppm range work to compress the
dynamic range of a loudspeaker.
Let's say we have an 8ohm resistor attenuating a tweeter in a
two-way loudspeaker, all of a sudden a musical transient comes
along which hits that resistor with a pulse. A cheap sand-cast
will momentarily increase it's resistance until that transient
is gone. This behavior is linked to the temperature Coefficient
of the resistor. So here then is a device that works like a perfect
dynamic range compressor.
Good resistors however with very low temperature coefficients
are virtually transparent to the signal but cost between 10 to
15 times as much as cheap sand casts.
Connections.
- All crossover components are hardwired component lead to component
lead then crimped producing a high pressure low contact area cold
weld, finally the joint is sealed using Eichmann 5% silver solder.
This method of connection is State Of The Art and infinitely superior
to even the best circuit board.
Can you imagine taking a $106 Silver Oil capacitor and poking
it's output lead into a hole on a PC board then blobbing on a
lump of solder?! this spells information loss.
Solder is not a good conductor and it's use is based mainly on
manufacturing convenience.
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