[TE Chea]

I don't have a inductance meter, I suspect these 2 things are
inductive, because a pair of capacitive ( 60 +ve & 60 -ve wires
are interwoven ) speaker cable ( made by UK's Monitor Audio
in 1983 ) can produce less distortion from the same m-c spkrs
& amplifier than straight ( not interwoven ) spkr cables can,
such that FM broadcasts sound more like CD`s.
I presume this is because this cable's capacitance compensates
for m-c spkrs & crossover networks' inductance, so power
factor ( between amplifier & spkrs ) is nearer to 1.
Does any1 here know better ?

[Don Pearce]

On Fri, 20 Apr 2007 01:34:49 +0800, "TE Chea" wrote:

I don't have a inductance meter, I suspect these 2 things are
inductive, because a pair of capacitive ( 60 +ve & 60 -ve wires
are interwoven ) speaker cable ( made by UK's Monitor Audio
in 1983 ) can produce less distortion from the same m-c spkrs
& amplifier than straight ( not interwoven ) spkr cables can,
such that FM broadcasts sound more like CD`s.
I presume this is because this cable's capacitance compensates
for m-c spkrs & crossover networks' inductance, so power
factor ( between amplifier & spkrs ) is nearer to 1.
Does any1 here know better ?


Speakers are complex loads. AT some frequencies they are inductors,
and at others they are capacitors. At a very few spots they are
resistive. In general a well designed crossover contributes very
little to the reactive impedance.

Speaker cables are generally inductive, not capacitive because they
have a characteristic impedance that is higher than the speaker
impedance across the audio range. In general the woven cables will
have an impedance close to 8 ohms, so they won't be capacitive or
inductive - just resistive.

So forget about power factors close to 1 - they don't exist in the
world of speakers.

d

--
Pearce Consulting
http://www.pearce.uk.com

--
Posted via a free Usenet account from http://www.teranews.com

[Eeyore]

TE Chea wrote:

I don't have a inductance meter, I suspect these 2 things are
inductive, because a pair of capacitive ( 60 +ve & 60 -ve wires
are interwoven ) speaker cable ( made by UK's Monitor Audio
in 1983 ) can produce less distortion from the same m-c spkrs
& amplifier than straight ( not interwoven ) spkr cables can,
such that FM broadcasts sound more like CD`s.
I presume this is because this cable's capacitance compensates
for m-c spkrs & crossover networks' inductance, so power
factor ( between amplifier & spkrs ) is nearer to 1.
Does any1 here know better ?

Speakers are best decsribed as 'complex loads'.

They will exhibit both variable impedance and inductive and capacitive
components of that impedance over the audio band.

Graham

[[email protected]]

On Apr 19, 1:34 pm, "TE Chea" wrote:
I don't have a inductance meter, I suspect these 2 things are
inductive,

The load presented by a speaker presents, depending
upon frequency, mixes of inductive, capacitive and
resistive impedances. One thing that can be said for
certain, at NO point does ANY speaker present a
purely inductive or capacitve impedance, and rarely
does one find even predominantly inductive or
capacitve impedances in speakers.

A typical 2-way vented box speaker might have
an impedanc curve is inductive-resistive up
to about 30 Hz, at which point its resistive, then
is capacitive-resistive to about 50 Hz, where it's
resistive, then goes inductive-capacitive up to
about 80 Hz, where it's resistive again, then goes
capactive-resistive up to about 250 Hz, where it
remains largely resistive until about 600 Hz, then
it goes inductive-resistive up until it goes resistive
at about 3000 Hz, where it goes capacutive resistive
until about 6000 Hz, and the it goes inductive-resistive
above that.

In such a speaker, it's most often the case that the
pahse shift of the impedance never exceeds +-45
degrees, which clearly says that at all frequencies, the
resistive portion of the impedance dominates.

So, the short answer to the question you pose in
the subject line is no: moving coil speakers are not
inductive loads, not predominantly, they're more
complex than that.

because a pair of capacitive ( 60 +ve & 60 -ve wires
are interwoven ) speaker cable ( made by UK's Monitor Audio
in 1983 ) can produce less distortion from the same m-c spkrs
& amplifier than straight ( not interwoven ) spkr cables can,
such that FM broadcasts sound more like CD`s.

This is a claim of a some cable manufacturers, but it
is a nonsense claim.

I presume this is because this cable's capacitance compensates
for m-c spkrs & crossover networks' inductance, so power
factor ( between amplifier & spkrs ) is nearer to 1.

False. while this might be true for a specific inductor
at a specific frequency, you cannot under any
circumstances "compemsate" for the inductance in
a speaker by a parallel capacitance, AND, it is
also unnecessary.

Ignoring for the moment that the "power factor"
arghument is simply irrelevant in loudspeakers
and low-impdeance stable amplifiers, the only
way of properly compensating for the complex
impedance of a speaker with the goal of reducing
power factor is with a circuit known as a complex
conjugate circuit. Such cricuits are very complicated:
they're as complicated as the impedance they are correcting.

The notion that a cable's capacitiance could compensate
such is impossible. for a number of reasons. First,
even picking ONE of the ranges over which the
speaker exhibits SOME inductance, the amount
of capacitance in the cable is off by huge factors.
Second, as shown above, it's doesn't work at all
because of the fact that the impedance swings
from inductive-resistive through resistive to
capacitive-restistive and back again many times over
the audio range. Third, the vast majority of modern
amplifiers do not have any problems driving such loads,
and those that do are very often made WORSE by
adding excessive parastic capacitances.

So if the claim is that a high-capactive cable compensates
for the fact that moving-coil speakers are inductive, the
claim falls flat on its face for many reasons.