bi-wire config question
 

"Serge Auckland" wrote in
message
Don Pearce wrote:
On Sun, 18 Jun 2006 13:36:03 +0100, Jim Lesurf
wrote:

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

I think that there is a far more fundamental problem at
work here, Jim. Glenn does not appear to understand that
what we have is a simple voltage divider, comprising the
cable and the speaker impedance. A 1 ohm cable, combined
with an 8 ohm speaker will result in a loss of about a
dB at all frequencies, and it doesn't matter what
signals are present. If the effect he is describing were to be real, then
picture a 1kHz signal in combination with a 10Hz signal.
The current due to the 10Hz would be changing from a
maximum to zero 20 times per second, so the loss at 1kHz
would be changing 20 times per second. The 1kHz would
actually be amplitude modulated by the 10Hz, rather than
simply superposed, which we know to be the case. His
misunderstanding of the physics really is happening at a
rather fundamental level. d

Absolutely! Glenn's theory would only be valid if cables
were non-linear, but we know that cables are extremely
linear, pretty much to the limits of measurement, so no
modulation can take place.

Exactly.

bi-wire config question
 

"tony sayer" wrote in message

FWIW I tend to prefer the Maplin cables as they give low
series resistance for just a few quid per cable. The
above URL uses them for example, so people can decide
for themselves what might suit for the lengths they
need.

Slainte,




Maplin guv?, pon me life their pricy..

Someone left some cables from the 400 kV re-wire their
doing round this way and the insulators..you've never
seen anything like 'em.


Usually aluminum, no?

bi-wire config question
 

On Sun, 18 Jun 2006 23:38:01 +0100, Glenn Richards
wrote:

Don Pearce wrote:

Now on the rare occasions I heard her low-fi all I could hear was
speaker cabinet resonance, harmonic distortion and a complete lack
of dynamics. But she couldn't hear the difference.
She obviously didn' invite you round that much then - did you insult
her by dissing her hi fi?

She didn't have a hi-fi. Or even a mid-fi. Low-fi was about the only way
to describe it.

Needless to say she didn't play it that much. I think it got turned on
about 3-4 times while I was round.


You need to work on your foreplay.

The interesting thing is that although she said she couldn't hear any
difference between her low-fi and my setup, she said that for some
reason she enjoyed hearing music more at my place.

So clearly she was *hearing* the differences, just not *perceiving* them.


You are the one for jumping to conclusions, Glenn.

Right both times. Speaker cables can and do make a difference to
sound. You've been told this over and over again.

You said they didn't. Now you're admitting that they do.


I'm not "admitting" anything. I am telling you they do with some
vehemence.

So if you're now agreeing that speaker cables can and do make a
difference, does it not follow that bi-wiring will sound different to
single-wiring?


No. Now you need to go and learn logic so you can follow a reasoned
argument.

Ignoring the maths for a moment and concentrating entirely on the sound,
if as you're suggesting bi-wiring produces a less accurate sound, but
that sound is actually more pleasant, surely it then makes sense to bi-wire?


I haven't suggested any such thing. What I have said is (now follow
carefully, ALL the words) that IF you have inadequately sized cables,
you are better off parallelling them than biwiring them. I have
explained why, and I have shown you how that hangs together in theory.
If you have realistically sized cables, it makes no difference if you
biwire, single wire or paint them purple.

It's the same principle as solid state vs valves. Solid state, when it
distorts, causes distortion on the even harmonics. Valve kit distorts on
the odd harmonics. And distortion on odd harmonics can actually sound
quite good (just ask any rock guitarist).


Wrong again - as ever. You are talking about the difference between
single ended and push-pull, not valves and solid state. And of course
a single ended amplifier has just as much odd harmonic distortion as a
double ended one - it is just masked by all the crap. And yes,
guitarists can use that distortion (although you might be interested
to know that just about all guitar amps are push-pull).

The bottom line with hi-fi is really quite simple - does it sound good?
If bi-wiring sounds better than single-wiring then bi-wire. If the
system sounds better with the bridging straps left on (so single-wired
but effectively with thicker cable) then leave the bridging straps on.
If your speakers sound better toed in 20 degrees (even though the
manufacturer recommends a toe-in of 5 degrees) then toe them in 20 degrees.


What you perceive is between your brain and your ears, and you are
welcome to enjoy whatever you like. Nobody here will criticize you for
it. But when you come here and claim that there is some objective
difference (ie one is better than the other), backed up by the most
ridiculous garbled non-science, expect to be contradicted.

With studio monitoring equipment the goal is to get the most accurate
sonic representation of what's "on the wire". With PA the goal is to
fill a space with sound. And with hi-fi the goal is to get the best and
most desirable sound to actually listen to the music. Which means that
for hi-fi the "rules" can occasionally be broken - and as described
above if it sounds better by doing things differently then do things
differently.


Hi Fi is short for High Fidelity. Do you know what fidelity is? It is
faithfulness - faithfulness to the original. If your goal is to get a
sound that pleases you, go for it; do it any way you like, but don't
call it Hi Fi, and don't claim it to be such around here.

A few years ago I had an amplifier (Ferrograph F307) that actually
sounded better if you ran a 3-core cable from the amp to the speakers,
splitting it halfway between the two speakers into two twin core cables,
with a common return back to the amplifier. (This arrangement obviously
won't work with a bridged amp!) It should have sounded wrong, but on
this particular amp and the particular speakers I was using at the time
it actually sounded better to do things that way.


Of course you did, Glenn. And did you discover this amongst a group of
friends who were muttering about how bad it sounded, then you went
round the back, fiddled with the wires and came back to cheers of
acclaim? Do you have a caped lycra suit with a big "G" on the front?
Your "stories" are getting boring.

And at about the same time, I took a smaller pair of speakers, connected
them in series then connected the free ends across the positive
terminals of the speaker outputs, thereby feeding the smaller speakers
with the L-R difference signal. Placing these speakers some way behind
the listening position gave quite an effective surround sound effect.
Purists would have had a heart attack, but it worked, and was a lot of fun.

I think we all did that when we were twelve. But most of us by then
knew enough that we didn't need to use a pair of speakers - one would
do the job. I think most of us sussed about five minutes later that as
interesting as it was, it sounded like crap.

Horses for courses, I guess.

OK, tell us the story about the racehorse that went so much faster
when you bolted its legs on backwards.

d

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

bi-wire config question
 

Arny Krueger wrote:
"Glenn Richards" wrote in
message

Ok, for those people that still don't "get it", here's an
experiment that will demonstrate visually what's going on:


Take a 12V DC power supply (one of those bench PSUs
capable of supplying several amps will suffice) and a 12V
1W bulb (any type will do, it's easier to perform the
experiment using a MES bulb and batten holder with screw
terminals though).


Connect the bulb to the power supply using 5 metres of
13-strand zip wire and power up. Observe the brightness
of the bulb.


Now take a second bulb and holder, and attach a few
inches of the same wire to the second holder. Connect the
second bulb in parallel with the first so that it is
"chained" from the first bulb, ie you've got 5m of cable
from PSU to first bulb, then a few inches from the first
bulb to the second bulb. Make this connection with the
power turned on.


As you connect the second bulb, you'll see the first
bulb's brightness decrease. This is caused by a voltage
drop in the cable. Disconnect the second bulb and the
brightness of the first will increase again.


Unfortunately this experiement is irrelevant to speakers, because in a
speaker there is a crossover which is frequency-selective.

The real flaw in Glenn's light bulb experiment is that the cold resistance
of a bulb is far lower than its resistance when on.
I don't have a 12v bulb to hand but a 100w 240v bulb measures 40 ohm cold,
and calculates at 576 ohm hot. So his first bulb will dim momentarily.
The change on disconnecting the second bulb will be less noticable.

And, of course, he didn't bother to make any measurements.
Does he even own a DVM?

--
Eiron

No good deed ever goes unpunished.

bi-wire config question
 

On Mon, 19 Jun 2006 07:26:52 +0100, Eiron wrote:

Arny Krueger wrote:
"Glenn Richards" wrote in
message

Ok, for those people that still don't "get it", here's an
experiment that will demonstrate visually what's going on:


Take a 12V DC power supply (one of those bench PSUs
capable of supplying several amps will suffice) and a 12V
1W bulb (any type will do, it's easier to perform the
experiment using a MES bulb and batten holder with screw
terminals though).


Connect the bulb to the power supply using 5 metres of
13-strand zip wire and power up. Observe the brightness
of the bulb.


Now take a second bulb and holder, and attach a few
inches of the same wire to the second holder. Connect the
second bulb in parallel with the first so that it is
"chained" from the first bulb, ie you've got 5m of cable
from PSU to first bulb, then a few inches from the first
bulb to the second bulb. Make this connection with the
power turned on.


As you connect the second bulb, you'll see the first
bulb's brightness decrease. This is caused by a voltage
drop in the cable. Disconnect the second bulb and the
brightness of the first will increase again.


Unfortunately this experiement is irrelevant to speakers, because in a
speaker there is a crossover which is frequency-selective.

The real flaw in Glenn's light bulb experiment is that the cold resistance
of a bulb is far lower than its resistance when on.
I don't have a 12v bulb to hand but a 100w 240v bulb measures 40 ohm cold,
and calculates at 576 ohm hot. So his first bulb will dim momentarily.
The change on disconnecting the second bulb will be less noticable.

And, of course, he didn't bother to make any measurements.
Does he even own a DVM?

No, the real flaw is that it shows nothing whatever about biwiring. It
only shows the inadequacy of too-thin wire. (something he has
subsequently admitted).

d

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

bi-wire config question
 

In article , Glenn Richards
writes
Don Pearce wrote:

Glenn, you have never been one to let anything as mundane as a fact
get in the way of your beliefs. Nice line in sanctimonious piety, by
the way.

More projecting I see...

But since you're bringing facts into this, how about this:

Fact - many people (myself included) can and do hear differences in
cable sound.

Fact - other people can't. That doesn't mean those differences aren't
real. It just means that some people can't hear them.

A case in point being my ex-girlfriend. She honestly could not tell the
difference between a £99 midi system and 5 grand's worth of separates.
Other than "your system goes louder".

Is that why she became the ex;-?....
--
Tony Sayer

bi-wire config question
 

In article , Arny Krueger
writes
"tony sayer" wrote in message

FWIW I tend to prefer the Maplin cables as they give low
series resistance for just a few quid per cable. The
above URL uses them for example, so people can decide
for themselves what might suit for the lengths they
need.

Slainte,




Maplin guv?, pon me life their pricy..

Someone left some cables from the 400 kV re-wire their
doing round this way and the insulators..you've never
seen anything like 'em.


Usually aluminum, no?



Steel cored Ally!.

Very "tight" replay, and a bit shiney;)....
--
Tony Sayer

bi-wire config question
 

In article , Don Pearce
wrote:


I think that there is a far more fundamental problem at work here, Jim.
Glenn does not appear to understand that what we have is a simple
voltage divider, comprising the cable and the speaker impedance. A 1 ohm
cable, combined with an 8 ohm speaker will result in a loss of about a
dB at all frequencies, and it doesn't matter what signals are present.

The problem here seems to me to be based on not understanding and applying
correctly the principle of linear superposition. Also some confusion over
the applicability of equivalent circuit analysis, etc.

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

bi-wire config question
 

In article , Bob Latham
wrote:
In article , Jim Lesurf
wrote:


Yes. If you wished to deliberately use cables with wildly different
series resistances, etc, then they could then interact with the load
impedances of the speaker units and alter the overall response
accordingly. However the levels of resistance required for this would
probably more cheaply and controllably be obtained by deliberately
adding low-value series resistors and shunt capacitors, etc, at the
speakers. This is usually called "modifying the crossover networks"...
;-

Just for a moment or two can we put aside blind listening test etc. and
imaginings please.

3 years ago we (better half and I) did the speaker lead thing and use
two different cables because we thought it sounded nicer. As I've said
before, we were not encouraged (in fact quite the opposite) to go for
mixed leads by the dealer and they thought it a bit strange.

What we found was that the Chord Odyssey cable made my speakers sound
sweeter for want of a better expression. The did tend to shout a little
on some choral works for example. Odyssey definitely seemed to reduce
this and make it more relaxed to listen to. As an aside they weigh an
absolute ton, the weight never fails to surprise me.

The problem is that unless you also tell us the specific details of the
comparison tests you performed, and how you collected and assessed the
results, no-one has any way to determine how reliably your reported
conclusions may be.

Hence you might be entirely accurate in what you state, and that the
changes of cables did indeed alter the system response, etc, in an audible
way which would cause what you report.

However this might be for reasons which have nothing to do with bi wiring
as such. Maybe due to some other change you made at the same time and
which you didn't notice or thought significant. For all I know, you *might*
have imagined it. No way to tell from what you say above. I can't say you
*did* imagine it, but nor can I say you didn't. No useful data upon which
to judge.

This means that your report is of little value as reliable evidence for the
claim that bi wiring actually altered the sounds produced in the case you
report. All your report tells us is that this *might* be so in one case,
but gives us no way to determine the probability of this being so.

If you want to obtain reliable evidence that can then be assessed by
yourself and others, and which might then be evidence that the bi wiring
was a reason for a change (rather than something else that didn't occur to
you) then you would need to do the comparison tests in an appropriate way.

I appreciate that you might not want to do this, but if you don't, then you
'results' will remain of undeterminable value - i.e. effectively worthless
as evidence for more than a statement of personal belief.


Could this be inductance? I would have thought that would not effect the
bass unless it was so high it would kill the treble.

We can't really tell as we lack the relevant data, etc. See below.

Any suggestions as to how I could track down the reason?

The problem is that the 'reason' may have nothing to do with the cables or
the bi wiring arrangement. Hence you would now need to do two things if you
really wish to clear this up:

1) Repeat the listening comparisons, using a protocol, etc, that will allow
you to randomise uncorrelated factors, ensure you only have the sounds to
go on, etc, and then collect enough data to be able to get some estimate of
the reliability of the results.

2) Measure/define the relevant parameters of the items being used/compared.

The above would allow you to distnguish not only if there *is* a reliably
audible change, but to distinguish between possible 'reasons'.

If you *do* want to do this I (and I expect others) would be quite happy to
advise on details. But it does take some time and effort, I'm afraid.

If you don't want to do the above, then we have no way to know what, if
anything, your report may mean.

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

bi-wire config question
 

In article , Glenn Richards
wrote:
Eiron wrote:


But apparently the way I carried out the test was invalid according to
some technicality made up by someone in here (I forget who). Like, who
elected you supreme commander anyway?

I am not quite sure who "someone in here" may be... Perhaps this is
because you haven't replied directly to my posts on this topic. :-)

However the problem is that - as yet - so far as I can tell, you haven't
actually specified the protocol, etc, you used for the test you reported.
Hence the 'technicality' seems to be that you haven't told us what we might
need to know to decide what (if anything) your report may mean.

You may be relieved, though, to learn that no-one has to be elected as
"supreme commander" to learn how to apply and use the scientific method and
hence obtain results whose value can be assessed. When doing so, you can
also discover the experimental methods people have developed over the years
to deal with the problems in obtaining useful results.

[snip]

The fact remains that many people can and do hear differences between
different cables. As I've said before, I was always highly sceptical
until I was given a very convincing demonstration of the differences.

It is certainly a 'fact' that people report this belief/conclusion. Alas,
people believe all kinds of things - often contradictory. So they might be
right, or they might be mistaken. The reason may be what they say, or it
might not. Hence it may be wise to judge their claims/beliefs on the basis
of being able to assess the reliability of the *evidence* they offer. To do
that, we have to be able to know and understand how they collected their
data. This (scientific) method is specifically designed to avoid having any
"supreme commander" telling them what to accept/reject, and allow them to
make their own well-informed decisions. :-)

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