UndrstndgBiWr.pdf

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Understanding BiWiring
April 2008
2621 White Road
Irvine CA 92614 USA
Tel 949 585 0111
Fax 949 585 0333
www.audioquest.com
Understanding BiWiring
Many of today’s speakers can be “BiWired”, meaning the speaker has
separate inputs for the woofer and separate inputs for the higher frequencies.
Should you BiWire? If so, should you BiWire with a single cable (Single
BiWire/SBW) or with two separate cables (Double BiWire/DBW)?
Is BiWiring so important that you should spend twice as much on speaker
cable? BiWiring is actually a way to get higher performance for the same
expenditure. The BiWiring question is not about how much money to spend,
but how to maximize performance and value.
Magnetic Fields and Bass Energy:
When using a single full-range speaker cable (not BiWiring) the large
amounts of bass energy carried within the single cable has an adverse
effect on the upper frequencies. In a BiWire set-up the cable feeding the
HF
higher frequencies no longer handles the large magnetic fields caused by
Network
the high current needed to produce bass. BiWiring does not affect the bass
fundamentals, but the treble
Cable
Connecting
signal now travels a less disturbed path. It’s a
Power
little
Amplifier
difference between swimming through waves versus through
like the
smooth water. Bass frequencies will sound better because bass definition
is actually located in the midrange and higher frequencies.
. It is always
LF
Network
worthwhile to take advantage of the benefits of BiWiring when the speaker
manufacturer has gone to the extra expense of providing this capability. The
performance benefits of reducing distortion in this way are substantial.
Conventional Amplifier-speaker wiring.
BiWiring and Cable Geometry:
Connecting Cable 1
HF
Network
Power
Amplifier
Connecting Cable 2
LF
Network
Standard bi-wiring arrangement.
When BiWiring,
the two (bass and treble) cables must either be identical, or
have essentially identical geometries.
If the cables have different geom-
etries they will have different capacitance and inductance. Capaci-
tance and inductance are the values used to create a loudspeaker’s low-pass
and high-pass filter networks, together making a crossover. Having different
values in the two cables effectively redesigns the crossover…not a good
thing! The integrity and coherence of the speaker will be compromised.
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For best performance, use two of the same cables. If the speaker has a low
crossover point (a 3-way speaker or a panel-hybrid such as Martin Logan)
much of the benefit of using two identical cables can be realized by using
two cables which have the same geometry, but which use
different qualities of metal.
CV-4
TYPE-4
In the example above CV-4
(with its superior Perfect-Surface Copper)
for
the upper frequencies is paired with Type-4 (which
uses Long-Grain Cop-
per)
to drive the bass. Why do this? It’s less expensive!
This “trick” does not work for 2-way speakers. They have their BiWire
access frequency in or above the midrange … music and voice and
practically everything else is in the midrange and must be given full respect.
When Bi-Wiring with 2-way speakers always use two identical cables.
BiWiring Within a Single Cable:
Another valid BiWire option (with proper cable design) involves the use
of a single speaker cable divided into separate “high” and “low”
frequency sections. We call this Single BiWire (SBW). This works better
with some cables than with others –
but BiWiring using two separate cables
is always better.
We do not recommend Single BiWire when using a Star-
Quad model (Type-2, Type-4, CV-4).
More importantly, please understand
that, except for the Rocket and Flat-Rock Series, it is better to use two less
expensive cables than to Single BiWire with one better cable.
Using two
pairs of CV-8 is better than a Single BiWired Mont Blanc, for example.
The Rocket Series
Rocket 33
Rocket 44
Rocket 88
Rockets are excellent for Single BiWiring
because they are essentially two
cables in a single outer jacket.
While great for use as full-range cables,
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these models, when used as Single BiWire cables, actually become a spe-
cialized true Double BiWire thanks to their two separate Star-Quad compo-
nents. The two groups of conductors have a degree of magnetic autonomy
found in no other single cable.
The Flat Rock Series
Rockefeller
Gibraltar
K2
While the Rocket Series and Flat-Rock Series are excellent for Single
BiWiring, the Earth-Feature Series (Monte Blanc and Volcano), are poor
choices for SBW. One of the significant advantages of the Earth Feature
cables is the unusually effective way they manage the relationships between
magnetic fields. The conductors spiral in opposite
directions, but the positive and negative groups form
two tubes whose relationship is constant and non-
changing. Dividing the conductors in these models
does very little to separate the magnetic fields of the
bass and treble groups.
The Earth-Feature Series is best when used full range – with speakers
having a single set of connectors – or when two are used per speaker in a
Double BiWire set up.
That leaves the 8-Series in which, for instance, Single BiWiring with CV-8 is
effective, though only half as effective as running a Double-BiWire
of CV-4.
You can Double BiWire by stacking connectors at the amp, or by simply or-
dering Double BiWire cables. AudioQuest simply joins the two cables togeth-
er at the amp end before attaching the terminations. The price for a double
BiWire pair is simply the same as adding together the price of the two ca-
bles, whether the same model or different models.
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