On Sun, 18 Jun 2006 12:40:17 +0100, Glenn Richards
wrote:

Don Pearce wrote:

As opposed to you, who has already proved in a previous post that
you have no idea how an earth loop works, interpreted "two signals"
to mean combining a stereo signal onto a single core and couldn't
understand the correlation between "unwanted signal" and "noise"
(hint - "noise" is any "unwanted signal") etc etc.
Glenn, I said no such thing - as that is complete nonsense. If that
is what you interpreted from what I said, it only illustrates your
lack of understanding.

No, that was exactly what you said. You were harping on about "why would
you send two signals down one cable", completely missing the point that
noise is a signal, just one that isn't wanted.

No, Glenn. What I said repeatedly was that what you needed for a
ground loop was one (minimum, two for stereo, obviously) signal
connection, and *two* ground connections. Those two *ground*
connections are what make a *ground* *loop*. See where the term comes
from now? So kindly don't misquote me. And just so that we are clear -
noise doesn't figure in ground loops, it is hum we are talking about.

It isn't me that is suffering from a lack of understanding here. I
suggest you go and take a look in the mirror.

So funny!

d

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

Don Pearce wrote:

OK - you snipped the substance, as you had no way of dealing with it.

I think the phrase "couldn't be bothered" springs to mind. But since you
insist...

So I will repeat it again:

yawn

First lets assume that your experiment is applicable. Now complete
it. Use you second case - with the two wires run separately right
back to the source ( for maximum brightness). Now take your short
piece of wire and join the two bulbs together. If biwiring made a
difference, there should be a change in brightness as you do this.
There is no change. All you have shown is that it is usually better
to have thicker wire.

My experiment was a very simple one, designed to demonstrate the effect
of a long run of cable acting like a series resistor. By strapping the
bulbs together when "bi-wired", you're then achieving "C = R / 2", where
C is the series resistance of the cable(s) between the bonding strap and
the amplifier (or power source in this case), and R is the series
resistance of each individual length of cable. Of course this assumes
that both runs of cable are identical.

Now, this experiment uses DC, so only demonstrates resistance. A DC
signal is not affected by inductance (or indeed capacitance between the
cores - series capacitance will block DC but parallel won't). So it
serves only to demonstrate one of several mechanisms in play that means
bi-wiring will give an improvement.

Go back and read my earlier posting where I stated that eventually
you'll reach a thickness of cable where the series resistance becomes so
low that this effect no longer occurs. But a cable this thick will
either be very unwieldy or (comparatively) very expensive, therefore
it's more convenient (or cost effective, as the case may be) to use two
runs of thinner/cheaper cable.

The second point is that the tweeter and woofer are not in parallel.
Does that surprise you? This because we are dealing with signals in
defined frequency bands, and we have a crossover, which presents a
high impedance to the cable in the stopband of each driver. [snip]

Yes, except - there's an equivalent series resistor in the feed to the
"high impedance load". So a voltage drop across the LF *will* affect the HF.

By bi-wiring, you split the signal before this "series resistor",
therefore a voltage drop across the LF cable won't affect the HF.

Right, enough time wasted on this for now. Let's see if your limited
understanding can make sense of the above...

--
Glenn Richards Tel: (01453) 845735
Squirrel Solutions http://www.squirrelsolutions.co.uk/

IT consultancy, hardware and software support, broadband installation

Don Pearce wrote:

And just so that we are clear - noise doesn't figure in ground loops,
it is hum we are talking about.

Hum *is* a form of noise. It's an unwanted signal - and noise is any
unwanted signal.

--
Glenn Richards Tel: (01453) 845735
Squirrel Solutions http://www.squirrelsolutions.co.uk/

IT consultancy, hardware and software support, broadband installation

On Sun, 18 Jun 2006 12:55:14 +0100, Glenn Richards
wrote:

Don Pearce wrote:

OK - you snipped the substance, as you had no way of dealing with it.

I think the phrase "couldn't be bothered" springs to mind. But since you
insist...

So I will repeat it again:

yawn

First lets assume that your experiment is applicable. Now complete
it. Use you second case - with the two wires run separately right
back to the source ( for maximum brightness). Now take your short
piece of wire and join the two bulbs together. If biwiring made a
difference, there should be a change in brightness as you do this.
There is no change. All you have shown is that it is usually better
to have thicker wire.

My experiment was a very simple one, designed to demonstrate the effect
of a long run of cable acting like a series resistor.

Really, is that all it was? Then why did you claim it illustrated the
beneficial effects of biwiring?

By strapping the
bulbs together when "bi-wired", you're then achieving "C = R / 2", where
C is the series resistance of the cable(s) between the bonding strap and
the amplifier (or power source in this case), and R is the series
resistance of each individual length of cable. Of course this assumes
that both runs of cable are identical.

C=R/2 whether they are strapped together or not. Do you really not see
this? (incidentally, please don't use C for a resistance, it is used
for capacitance).

Now, this experiment uses DC, so only demonstrates resistance. A DC
signal is not affected by inductance (or indeed capacitance between the
cores - series capacitance will block DC but parallel won't). So it
serves only to demonstrate one of several mechanisms in play that means
bi-wiring will give an improvement.

But it clearly shows that biwiring (ie not strapping together at the
bulb end) has no effect. What does have an effect is using a
sufficiently thick cable. If you are going to use a thought experiment
- even as poor a one as this - to prove a point, at least draw the
correct conclusion.

Go back and read my earlier posting where I stated that eventually
you'll reach a thickness of cable where the series resistance becomes so
low that this effect no longer occurs. But a cable this thick will
either be very unwieldy or (comparatively) very expensive, therefore
it's more convenient (or cost effective, as the case may be) to use two
runs of thinner/cheaper cable.

Fine, but the effect is the reverse of what you claim. If you have a
cable so thin that it is harming the sound, then you don't improve it
by biwiring - the same cable resistance is still feeding each driver,
so the loss is the same. What you need to do is parallel the cables so
they are both connected together at both ends. This will have a good
effect because you have now halved the resistance of the cable feeding
each unit.

The second point is that the tweeter and woofer are not in parallel.
Does that surprise you? This because we are dealing with signals in
defined frequency bands, and we have a crossover, which presents a
high impedance to the cable in the stopband of each driver. [snip]

Yes, except - there's an equivalent series resistor in the feed to the
"high impedance load". So a voltage drop across the LF *will* affect the HF.


No it won't. Go read some theory on diplexing.

By bi-wiring, you split the signal before this "series resistor",
therefore a voltage drop across the LF cable won't affect the HF.

Right, enough time wasted on this for now. Let's see if your limited
understanding can make sense of the above...

Glenn, you are living in a muddle. Please go and study.

d

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

On Sun, 18 Jun 2006 13:03:12 +0100, Glenn Richards
wrote:

Don Pearce wrote:

And just so that we are clear - noise doesn't figure in ground loops,
it is hum we are talking about.

Hum *is* a form of noise. It's an unwanted signal - and noise is any
unwanted signal.

We have three unwanteds in audio:

Hum - induced from the mains
Noise - internally generated random fluctuations
Distortion - signal-related products of nonlinear distortion

Go and learn the difference between them. Then find out why you have
to treat each differently, how they have different causes and of
course different remedies.

And of course none of these is signal, which is defined as the wanted
stuff.

d

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

In article , Glenn
Richards wrote:
Serge Auckland wrote:

No it isn't! Your experiment is being done with dc. Repeat the
experiment with 50Hz to one bulb and 10kHz to the second bulb, both
bulbs being fed through a single amplifier and fed through a simple
capacitor or inductor "crossover". You will now see that the bulbs
don't change their brightness.

Makes no difference, AC or DC.

Do the experiment Serge described and you will find that the results show
he is correct in what he says. Then as Don has suggested, investigate
diplexing.

Bear in mind that what he describes is the kind of technique routinely
employed and studied by electronic engineers. Indeed, I'd suspect that
more than one undergrad lab may have what Serge describes as an
experiment to show this to students. It is the basis of frequency
division multiplexing in transmission line systems. :-)


Series resistance is still the same, regardless of line frequency.


Actually, not necessarily so. It is quite possible for a cable to
have a resistance that varies with frequency. :-) However even if we
ignore this, what Serge says is correct.


That experiment was to illustrate a concept, not specifics. The
principle is exactly the same.

Only for the specific case you gave. The snag is that loudspeakers aren't
simply resistors.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

In article , Don Pearce
wrote:
On Sun, 18 Jun 2006 12:55:14 +0100, Glenn Richards
wrote:



The second point is that the tweeter and woofer are not in parallel.
Does that surprise you? This because we are dealing with signals in
defined frequency bands, and we have a crossover, which presents a
high impedance to the cable in the stopband of each driver. [snip]

Yes, except - there's an equivalent series resistor in the feed to the
"high impedance load". So a voltage drop across the LF *will* affect
the HF.


No it won't. Go read some theory on diplexing.

There may be some effect if the 'out of band' impedances are not suitably
high. However provided the cables and signal source have a low impedance,
etc, they are likely to be irrelevant in practice as they would be too
small to have audible significance.

As usual, it is always possible for someone to assemble a system with
extraordinarily inappropriate properties, but this seems unlikely to be an
issue with sensible cabling, etc, in a domestic audio system.

By bi-wiring, you split the signal before this "series resistor",
therefore a voltage drop across the LF cable won't affect the HF.

I think Don is trying to explain that this will also be the case with
conventional wiring given sensible cables, etc. With a non-zero speaker
resistance and conventional wiring the LF signals will alter the
speaker-end voltages slightly *at LF frequencies* - which the HF speaker is
supposed not to be reproducing, and for which the HF unit and network may
have a high impedance. Linear superposition is your friend here... ;-

I also think that both Don and Serge are pointing out that your approach is
too simplistic, and hence inappropriate and misleading.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

On Sun, 18 Jun 2006 12:55:14 +0100, Glenn Richards
wrote:

OK - you snipped the substance, as you had no way of dealing with it.

I think the phrase "couldn't be bothered" springs to mind. But since you
insist...

OK Glenn, maybe you can't be bothered (yeah, right) but I can. I've
done the work for you and simulated the two effects - biwire, or
parallel wire, joined at the far end - in PSpice. The results
vindicate my position completely.

Of course, Spice could be totally invalid along with a couple of
hundred years of theory, I suppose...

Anyway read and weep:

http://81.174.169.10

d

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

Don Pearce wrote:

OK Glenn, maybe you can't be bothered (yeah, right) but I can. I've
done the work for you and simulated the two effects - biwire, or
parallel wire, joined at the far end - in PSpice. The results
vindicate my position completely.

No they don't.

You've only placed a "lossy" cable on one leg of the speaker cable. So
you've got effectively a 5 metre run of cable from the positive speaker
output, then a short (as close to zero ohms as possible) run back to the
ground point on the amplifier.

Also, most crossovers I've seen often only have a series inductor (for
LF) or series capacitor (for HF), and don't bother strapping L or C
across the load. Admittedly some do, but I just took the plate off the
back of one of my Mission 760iSE speakers, there's a single inductor in
series with the LF driver and a single cap in series with the HF driver.
Clearly a case of KISS (Keep It Simple, Stupid).

Of course, Spice could be totally invalid along with a couple of
hundred years of theory, I suppose...

So how do you explain the fact that when the speakers are bi-wired they
sound better (clearer and sharper treble, more detail etc)? And when
single-wired they sound muddy by comparison?

Hint: the standard uk.rec.audio cop-out of "it's all in your mind" is
not a valid response. Of course it's all "in your mind", your ear only
gathers sound and turns it into electrical signals. It's your mind (or
more technically your brain) that interprets those electrical signals as
noises, whether pleasant or unpleasant. Just in case you feel like
getting pedantic.

Remember that computers do what you tell them to do, not what you want
them to do. So if your model isn't tying up with the observed effects
then your model is obviously wrong.

I'll give you a B+ for effort, E for accuracy. Your computer model does
not match the observed effects. Now, take the effort you're about to
expend on trying to prove me wrong and channel it into finding out why
the observable and repeatable effects occur.

Head teacher's comment: Plenty of enthusiasm, needs to channel self
better. D-.

--
Glenn Richards Tel: (01453) 845735
Squirrel Solutions http://www.squirrelsolutions.co.uk/

IT consultancy, hardware and software support, broadband installation

On Sun, 18 Jun 2006 14:45:02 +0100, Glenn Richards
wrote:

Don Pearce wrote:

OK Glenn, maybe you can't be bothered (yeah, right) but I can. I've
done the work for you and simulated the two effects - biwire, or
parallel wire, joined at the far end - in PSpice. The results
vindicate my position completely.

No they don't.

You've only placed a "lossy" cable on one leg of the speaker cable. So
you've got effectively a 5 metre run of cable from the positive speaker
output, then a short (as close to zero ohms as possible) run back to the
ground point on the amplifier.

Also, most crossovers I've seen often only have a series inductor (for
LF) or series capacitor (for HF), and don't bother strapping L or C
across the load. Admittedly some do, but I just took the plate off the
back of one of my Mission 760iSE speakers, there's a single inductor in
series with the LF driver and a single cap in series with the HF driver.
Clearly a case of KISS (Keep It Simple, Stupid).

Of course, Spice could be totally invalid along with a couple of
hundred years of theory, I suppose...

So how do you explain the fact that when the speakers are bi-wired they
sound better (clearer and sharper treble, more detail etc)? And when
single-wired they sound muddy by comparison?

Hint: the standard uk.rec.audio cop-out of "it's all in your mind" is
not a valid response. Of course it's all "in your mind", your ear only
gathers sound and turns it into electrical signals. It's your mind (or
more technically your brain) that interprets those electrical signals as
noises, whether pleasant or unpleasant. Just in case you feel like
getting pedantic.

Remember that computers do what you tell them to do, not what you want
them to do. So if your model isn't tying up with the observed effects
then your model is obviously wrong.

I'll give you a B+ for effort, E for accuracy. Your computer model does
not match the observed effects. Now, take the effort you're about to
expend on trying to prove me wrong and channel it into finding out why
the observable and repeatable effects occur.

Head teacher's comment: Plenty of enthusiasm, needs to channel self
better. D-.

Good grief - there really is no end to it.

OK, I've done all I can - anybody else feel like trying?

d

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