Don, Noons: TIF v. JPG. More samples.

[Colin D]

Having designed and built many "good amplifiers" over the years, I'm
comfortable with what I know about them.

Yes, you probably are. But I see from another post of yours in this
thread that you are a long-time guitar player/musician. That's fine,
but that's the field where you can claim to be professional, not
electronics. Building and using amplifiers for professional performance
does not make you a professional in electronic design, any more than I,
as a professionally trained electronics person can claim to be a pro
musician - in fact I can't play any instrument.

Then, what do you think the purpose of feedback might be?

What sort of feedback do you mean? There is positive feedback, useful
for making oscillators, and there is negative feedback, useful for
reducing distortion and impedance. Further, feedback by itself has
nothing to do with damping factor. There are many applications using
negative feedback that do so for other reasons than damping. Damping is
of concern only when ringing or overshoot might be a problem, whether
electronic ringing as in some filter circuitry, or mechanical as in
speakers. Negative feedback applied around one or more stages of
amplification does three things; it reduces the overall gain of the
circuit, it reduces distortion from the included stages, and it lowers
the impedance of the output stage. Note that it does not affect the
load impedance the circuit is designed to drive; it lowers the 'internal
impedance' of the output stage.

Tell that to Altec, Leslie and many others who have done exactly that for
a very long time. With tube amps.

(much snipped)

Your assertion, above, is that "a 100-*WATT* signal requires the cable to
carry 25 amps r.m.s. which is a lot for lamp cord." How did you arrive at
that load factor independent of voltage?

Because knowing voltage is not necessary to calculate current from power
and resistance figures. See Ohm's Law below.

But, here, I have to admit to a math error. It's a long time since I
dealt with Ohm's Law at the basic level, and I overlooked that
calculating the current required to deliver 100 watts into 4 ohms uses
the formula I=[(W/R)^0.5]. I left off the square root, so the real
current for 100 watts into 4 ohms is 5 amperes, not 25. (hides face in
shame). {:-(

However (feeling a bit brighter), this does not alter the argument
around damping factor, since the cable resistance is what's important,
not the current capacity.

Apparently, you think that 25A @
120V = 25A @ 12V. Since you're into "experiments", here's an easy one for
you: for which one would you let your body complete the circuit? Try them
both, and decide. ;-)

Of course I don't think that 25A @ 120V = 25A @ 12V, and that isn't what
I said. Reading your last paragraph, I get the feeling you aren't too
familiar with Ohm's law. Here is a link that explains it all:

http://www.the12volt.com/ohm/ohmslaw.asp

I hope you find it useful.

I think we have pretty different ideas about what constitutes a "good
amplifier". Since this discussion is way OT here, why not drop over to,
say, rec.audio.pro and make such claims. I'm sure that many will be glad
to sort out your notions.

I think we can end it here, without prolonging the discussion. I
realize now that you are talking about guitar amplifiers and similar,
which are somewhat different animals than high-end amplifiers in sound
reproduction systems playing CD's or vinyl or whatever, which is where I
an coming from.

Regards,

Colin D

 

[Colin D]

High-end audio is the domain of wannabe electrical
engineers. His description of vacuum tubes as
valves was the tipoff. I mean, they *are*... but only
dweebs use that expression.

Interesting, but wrong, Rafe. Dweeb I am not. The generic term 'valve'
was/is used by English Commonwealth ex-Empire countries like Australia,
New Zealand (my country) and others. 'Tube' was/is used mainly by
America and some others. I gotta say, though, that given the shapes of
some earlier and special-purpose valves, the term 'tube' is hardly
appropriate {The valve/tube was invented by Lee De Forest 100 years ago, in 1906, and
looking at the pictures, it should have been called a globe or bulb, as
it was quite round, not at all tubular.

Colin D.

PS: Electrical engineers deal with electricity. Electronic engineers
deal with electronics. Different fields. Thought you'd like to know
that {

 

[Raphael Bustin]

PS: Electrical engineers deal with electricity. Electronic engineers
deal with electronics. Different fields. Thought you'd like to know
that {

Call it what you will. I have a BSEE. It says "Electrical
Engineering" on the diploma. Some work with megawatts,
some with kilowatts, some with microwatts. The theory's
all the same. A transmission line is a transmission line.

Now it's all down to firmware and HDL. Sigh. I miss
the smell of fried bakelite in the morning.


rafe b
www.terrapinphoto.com

Big wheel turning by the fire and rod
Small wheel turning by the grace of god
Every time that wheel turn round
Bound to cover just a little more ground

 

[Colin D]

Call it what you will. I have a BSEE. It says "Electrical
Engineering" on the diploma. Some work with megawatts,
some with kilowatts, some with microwatts. The theory's
all the same. A transmission line is a transmission line.

Now it's all down to firmware and HDL. Sigh. I miss
the smell of fried bakelite in the morning.

Yeah, there are some things I miss too, like the ethereal ionizing glow
in the final bottles when you apply the h.t., and the bright sky blue
glow of mercury vapor rectifier valves/tubes ... but those days are well
past now.

Once, a year or two back, I was called to look at an old tube
transmitter that was being used for local coverage on 1602 kHz for the
blind, reading news and so on. They had a young technician from another
BC station to look at it, but he was modern transistor/fet trained. He
was out of his depth with the old tube job, so I went in to give him a
hand. Well, I fired up the heaters and the intermediate h.t. for the
oscillator and drivers, and checked the frequency, which turned out to
be 6408 kHz, because the young guy had inadvertently tuned the
oscillator to the second harmonic, and the drivers were doubling as
well. I set that right, checked the final neutralizing, and dialled up
the final HT, from memory about 7Kv. I was rather casually checking the
final tuning, when this young fella said something about the tubes, and
I remember replying that there was about 7,000 volts on the anodes of
these here four final bottles. He went as white as a sheet, and backed
off to the far end of the hut, scared witless, not only because of the
voltage, but the glowing finals, the flickering merc.vapor rectifiers,
the invasive hum of the power supply tranny, all added up to the thing
appearing to be alive. I never saw him again after that.

Colin D.

 

[Neil Gould]

Yes, you probably are. But I see from another post of yours in this
thread that you are a long-time guitar player/musician. That's fine,
but that's the field where you can claim to be professional, not
electronics.

Rather than toss insults, perhaps it would be better if you spoke of
something you know of? From the period of roughly 1968 through 1990, I
earned my living designing, building, and selling pro audio, video, and
sound reinforcement systems. During that time, I was also a dealer for EV,
Altec, JBL, BGW, and other high-end products and over that period also
owned two recording studios. From your childish need to insult and present
multiple erroneous yet obfuscating conclusions, my guess is that you
haven't been alive as long as I've been in business, so your opinion about
my "professional involvements" and/or education are fairly irrelevant.

Of course I don't think that 25A @ 120V = 25A @ 12V, and that isn't
what I said. Reading your last paragraph, I get the feeling you
aren't too familiar with Ohm's law.

It is what you implied with your statement about power (W) that ignored
voltage. The simple fact is that YOU brought up the power handling
capability of lamp cord as a reason not to use it as speaker cable, so
that was germain to the point I was addressing, while Ohms law is not. As
watts can be computed more directly by W=V*A, doing so might have exposed
your erroneous thinking sooner and saved you from making yet another
incorrect assertion.

I think we can end it here, without prolonging the discussion. I
realize now that you are talking about guitar amplifiers and similar,

No, I was not talking about "guitar amplifiers and similar"; I was talking
about pro audio amps, speakers, and speaker cable. Throughout this
discussion, your assertion has remained that speaker runs typical of home
audio -- e.g. those of less than 20' -- can result in an audible impact
due to cable resistance of >=18 Ga. lampcord, which is an absurdity.

Again, I invite you to make such statements in an appropriate NG, such as
rec.audio.pro, where there will be many who will straighten you out. No
need to take my word for it.

Regards,

Neil

 

[Raphael Bustin]

Rather than toss insults, perhaps it would be better if you spoke of
something you know of? From the period of roughly 1968 through 1990, I
earned my living designing, building, and selling pro audio, video, and
sound reinforcement systems. During that time, I was also a dealer for EV,
Altec, JBL, BGW, and other high-end products and over that period also
owned two recording studios. From your childish need to insult and present
multiple erroneous yet obfuscating conclusions, my guess is that you
haven't been alive as long as I've been in business, so your opinion about
my "professional involvements" and/or education are fairly irrelevant.

Like I said... the domain of wannabe electrical engineers.


rafe b
www.terrapinphoto.com

 

[Neil Gould]

Rather than toss insults, perhaps it would be better if you spoke of
something you know of? From the period of roughly 1968 through 1990,
I earned my living designing, building, and selling pro audio,
video, and sound reinforcement systems.

[...]

Like I said... the domain of wannabe electrical engineers.

I'm not a "wannabe" anything, Rafe. EE is not my field, though an
understanding of electronics is essential to my work.

The fact of the matter is that Colin's assertion...

"[...] fat, expensive, low-resistance speaker cable do matter, if you are
running a high-end amplifier/speakers
combo. [...]"

as a claim that "lamp cord" will have an audible impact on a typical
"high-end" audio system is demonstrably false, even using the formulae he
presented and resistance values for 18 ga. wire. Further, IMO, a good
audio amplifier will have independent channels, at least from the power
transformer back, which clearly differs from Colin's notion that a "good
amplifier" can have channel interaction, as implied by his statement:

"The AWG figure for 18g wire is 6.385 ohms/1000ft. In real terms, if you
have a run of say, 20 ft to your speaker, that's 40 feet of wire total
[...]"

If you don't understand these points, it only makes me wonder just what
the two of you *do* know, but it sure isn't high-end audio.

Neil

 

[Raphael Bustin]

If you don't understand these points, it only makes me wonder just what
the two of you *do* know, but it sure isn't high-end audio.

It's a tempest in a teapot, Neil. I have no real opinion
on the matter, but I'm generally in the lamp-cord camp.

I worked for years (during college and last 2 yrs of HS)
selling high-end audio. Worked for about six months
at DBX, in 1975, which is where I learned to despise
audio hacks.

Ignoring DBX, my professional work as an EE has never
involved audio. In fact these days it has mostly to do
hardware and firmware for digital imaging.

<http://www.sigmatel.com/documents/05SIG111_STDC3000.pdf>


rafe b
www.terrapinphoto.com

 

[James McNangle]

Call it what you will. I have a BSEE. It says "Electrical
Engineering" on the diploma. Some work with megawatts,
some with kilowatts, some with microwatts. The theory's
all the same. A transmission line is a transmission line.

Now it's all down to firmware and HDL. Sigh. I miss
the smell of fried bakelite in the morning.

I have a Bachelor of Electrical Engineering degree. We learnt about valves,
with one lecture on those newfangled semiconductors. Computers were mentioned
-- Bureau of Statistics had a couple of impossibly expensive monstrosities, but
no one suggested we would ever have anything to do with them. One student had a
transistor for his final year project.

My first job was designing a transistorised governor for water turbines. I
accidentally tripped off a 22MW turbine one morning during the morning peak,
when I connected an AVO in the wrong place. I was NOT popular with the
management!

My last job was designing antiviral software. So I helped to found the new
profession of Computer Virologist -- one that would have been totally
inconceivable when I was a student.

And the best thing about the improvements in electronics over the years?
Freedom from the dread that any slight carelessness could discharge a bunch of
electrolytics charged to 250 volts through your body.


James McNangle

 

[Colin D]

Rather than toss insults, perhaps it would be better if you spoke of
something you know of? From the period of roughly 1968 through 1990, I
earned my living designing, building, and selling pro audio, video, and
sound reinforcement systems. During that time, I was also a dealer for EV,
Altec, JBL, BGW, and other high-end products and over that period also
owned two recording studios. From your childish need to insult and present
multiple erroneous yet obfuscating conclusions, my guess is that you
haven't been alive as long as I've been in business, so your opinion about
my "professional involvements" and/or education are fairly irrelevant.

You are as wrong there as anywhere, Neil. My para. above was a
deduction from one of your other posts. It is not, and was not intended
to be, an 'insult'. Musicianship does not confer electronic
qualifications. Neither does being a dealer in numerous makes of gear.
A direct question: have you any formal qualification, trade or tertiary
training in electronics? I have both trade and tertiary qualifications
in electronics, gained when it was normal to work down to component
level, not board changers and chip users as many are these days.

Also, your guess as to how long I have been alive is wildly astray as
well, and for that matter bears no relevance at all to my opinion.
Going by your dates of 1968 - 1990, you are likely a bit younger than
me. I won't see sixty-odd again, so you can work out how much
experience I have.

It is what you implied with your statement about power (W) that ignored
voltage.

It is *unnecessary* to know the voltage. See below.

The simple fact is that YOU brought up the power handling

capability of lamp cord as a reason not to use it as speaker cable,

That was a secondary reason. The primary reason, which started this
discussion, was the resistance of speaker cable compromising the
amplifier's ability to control the speakers. Also, as I was reminded by
another poster, cable resistance can cause distortion from
overshoot-generated back emf to be coupled into the mid-range and
tweeter units, unless separate cables are run to those units.

so
that was germain to the point I was addressing, while Ohms law is not. As
watts can be computed more directly by W=V*A, doing so might have exposed
your erroneous thinking sooner and saved you from making yet another
incorrect assertion.

That 'assertion' was a mistake that I realized, acknowledged, corrected,
and apologized for. For your part, you simply accepted my figure of 25
amperes without realizing it must be wrong.

Also, I note you left my apology out of your quote there, not very
charitable, I might say.

Calculating current from power and resistance is perfectly valid, indeed
normal, when you have those two values to hand. Using W=V*A requires
you to measure the voltage, a totally unnecessary step. It's the little
things like this that make me believe you are neither formally
qualified, nor fully understand Ohm's Law.

No, I was not talking about "guitar amplifiers and similar"; I was talking
about pro audio amps, speakers, and speaker cable. Throughout this
discussion, your assertion has remained that speaker runs typical of home
audio -- e.g. those of less than 20' -- can result in an audible impact
due to cable resistance of >=18 Ga. lampcord, which is an absurdity.

It is measurable on an oscilloscope. Considering the lengths designers
go to to minimize distortion in amplifiers, usually achieving less than
0.1% THD at full power *into a dummy load*, why would they overlook
measurable distortion from a speaker?

Again, I invite you to make such statements in an appropriate NG, such as
rec.audio.pro, where there will be many who will straighten you out. No
need to take my word for it.

Like any newsgroup, r.a.p. is inhabited by experts and idiots, and a
whole gamut in between. Answers there would be as varied as we are, so
I don't see the need. We should agree to disagree here. I'm not going
to sway your belief, and you are not going to sway mine, so let's leave
it at that.

 

[Colin D]

Rather than toss insults, perhaps it would be better if you spoke of
something you know of? From the period of roughly 1968 through 1990,
I earned my living designing, building, and selling pro audio,
video, and sound reinforcement systems.

[...]

Like I said... the domain of wannabe electrical engineers.

I'm not a "wannabe" anything, Rafe. EE is not my field, though an
understanding of electronics is essential to my work.

An 'understanding' is not a qualification, Neil. It's a collection of
empirically-derived notions, no competition for formal training.

The fact of the matter is that Colin's assertion...

"[...] fat, expensive, low-resistance speaker cable do matter, if you are
running a high-end amplifier/speakers
combo. [...]"

as a claim that "lamp cord" will have an audible impact on a typical
"high-end" audio system is demonstrably false, even using the formulae he
presented and resistance values for 18 ga. wire.

Just how would you demonstrate it is false, Neil? You can't do it with
instruments, since they will show that it exists. Oh, I see, you can't
hear any difference? Great. You're like me, over the hill when it
comes to acute hearing. You cannot rely on your ears.

Further, IMO, a good

audio amplifier will have independent channels, at least from the power
transformer back, which clearly differs from Colin's notion that a "good
amplifier" can have channel interaction, as implied by his statement:

Power transformer? Perhaps you mean output transformer. Does that mean
you are talking about tube or early transistor amplifiers that used
output transformers?

"The AWG figure for 18g wire is 6.385 ohms/1000ft. In real terms, if you
have a run of say, 20 ft to your speaker, that's 40 feet of wire total
[...]"

If you don't understand these points, it only makes me wonder just what
the two of you *do* know, but it sure isn't high-end audio.

A friendly warning here, Neil. I am tertiary qualified, Rafe says he is
tertiary qualified, you say you have 'an understanding'.

Quit while you think you're ahead.

Colin D.

 

[Neil Gould]

You are as wrong there as anywhere, Neil. My para. above was a
deduction from one of your other posts.

Another *incorrect* deduction, Colin.

It is not, and was not
intended to be, an 'insult'. Musicianship does not confer electronic
qualifications. Neither does being a dealer in numerous makes of
gear.

I agree, and an EE doesn't make one proficient in pro audio, even though
the basic electronics should be well understood.

A direct question: have you any formal qualification, trade or
tertiary training in electronics?

Why, yes, I do.

I have both trade and tertiary
qualifications in electronics, gained when it was normal to work down
to component level, not board changers and chip users as many are
these days.

Well, as I started in the late '50s with short wave radio, it wasn't

Also, your guess as to how long I have been alive is wildly astray as
well, and for that matter bears no relevance at all to my opinion.
Going by your dates of 1968 - 1990, you are likely a bit younger than
me. I won't see sixty-odd again, so you can work out how much
experience I have.

So, I'm wrong about that, and would appreciate the courtesy that your age
should bring. A valid point of view does not require insults or
presumptions.

It is *unnecessary* to know the voltage. See below.

The simple fact is that YOU brought up the power handling

That was a secondary reason. The primary reason, which started this
discussion, was the resistance of speaker cable compromising the
amplifier's ability to control the speakers.

Except for two things:
* The ability to control speakers _accurately_ is a matter of being able
to deliver the necessary _voltage_ to the speaker.

* The ability to deliver the necessary voltage depends more on the
efficiency of the speaker than the damping factor of the amplifier. Most
decent audio amps will have a sufficiently low output impedance to provide
adequate voltage to control a reasonably efficient speaker, but that is
only one factor, and while the damping factor may be somewhat useful to
compare amps "on the shelf" if comparative data is also supplied, it's not
a very useful one in determining the performance of a system because
speakers are not pure resistive loads and vary widely due to many factors,
including the type of enclosure used.

That 'assertion' was a mistake that I realized, acknowledged,
corrected, and apologized for. For your part, you simply accepted my
figure of 25 amperes without realizing it must be wrong.

I simply didn't throw it in your face before, as it didn't affect the
point at hand, which was your statement about the power handling ability
of lamp cord in an audio application.

It is measurable on an oscilloscope. Considering the lengths
designers go to to minimize distortion in amplifiers, usually
achieving less than
0.1% THD at full power *into a dummy load*, why would they overlook
measurable distortion from a speaker?

Well, that says a lot about your perspective, anyway. Typically, a dummy
load is simply a resistor capable of handling the power from the
amplifier. Surely, you realize that this in no way emulates the
characteristics of a speaker; that a speaker's impedance can vary widely
depending on such things as where the cone is and where it has to be next
to represent a waveform accurately?

The performance of a particular speaker/amp combination can certainly be
plotted, but it won't provide much useful information about other speakers
with that amp, or other amps with that speaker. IMO, the impact of short
runs of lampcord is so far below those variables as to be a non-issue. On
that last point, we may agree to disagree.

Neil

 

[Neil Gould]

On Sat, 22 Apr 2006 11:09:08 GMT, "Neil Gould"


Rather than toss insults, perhaps it would be better if you spoke
of something you know of? From the period of roughly 1968 through
1990, I earned my living designing, building, and selling pro
audio, video, and sound reinforcement systems. [...]

Like I said... the domain of wannabe electrical engineers.

I'm not a "wannabe" anything, Rafe. EE is not my field, though an
understanding of electronics is essential to my work.

An 'understanding' is not a qualification, Neil. It's a collection of
empirically-derived notions, no competition for formal training.

Agreed. Good thing I do have formal training in electronics, then. ;-)

When I need an EE, I hire one, and, I know enough to know when I need one
and when I don't.

The fact of the matter is that Colin's assertion...

"[...] fat, expensive, low-resistance speaker cable do matter, if
you are running a high-end amplifier/speakers
combo. [...]"

as a claim that "lamp cord" will have an audible impact on a typical
"high-end" audio system is demonstrably false, even using the
formulae he presented and resistance values for 18 ga. wire.

Just how would you demonstrate it is false, Neil?

Based on the fact an efficient speaker can present a fairly high impedance
to an amplifier that will still have adequate current to provide the
voltage to control a speaker accurately, therefore, the reduction in
damping factor in a <= 20' length of, say 18 ga. vs. 16 ga. wire won't
result in a change of sufficient dB to make an audible difference.

You can't do it
with instruments, since they will show that it exists. Oh, I see,
you can't hear any difference? Great. You're like me, over the hill
when it comes to acute hearing. You cannot rely on your ears.

Why rely on our ears? There have been many blind listening tests that you
can access should you desire to do so, and think that's the way to go.

Further, IMO, a good

Power transformer? Perhaps you mean output transformer.

No, I meant power transformer. You know, that heavy thing that one finds
in non-switching power supplies? My notion of "a good amplifer" will at
least have separate power supplies for each channel, and at the very least
will not have channel interaction based on speakers connected to separate
outputs. Why else would you double the run of speaker wire to calculate
resistance, unless you were simply trying to obfuscate the issue?

Neil

 

[Colin D]

Well, that says a lot about your perspective, anyway. Typically, a dummy
load is simply a resistor capable of handling the power from the
amplifier. Surely, you realize that this in no way emulates the
characteristics of a speaker; that a speaker's impedance can vary widely
depending on such things as where the cone is and where it has to be next
to represent a waveform accurately?

Of course. But amplifier performance has to be measured in a repeatable
manner, hence dummy loads, which while not presenting the same
conditions as a speaker, are nevertheless a standard method of
determining amplifier maximum power and THD figures.

The performance of a particular speaker/amp combination can certainly be
plotted, but it won't provide much useful information about other speakers
with that amp, or other amps with that speaker. IMO, the impact of short
runs of lampcord is so far below those variables as to be a non-issue. On
that last point, we may agree to disagree.

With *short* runs of cable, I will agree. The criterion is how much
resistance the cable interposes between the amp. and speaker. Once the
cable resistance begins to seriously degrade the damping factor, or
becomes a significant percentage of the speaker impedance, the
performance will drop. This may not be an actual problem with main
speakers within, say 5 or 10 feet of the amp, but surround sound setups
with rear speakers at the other end of the room, and cabling run around
the perimeter, its easy to get runs of 30 feet or more. At that
distance, lamp cord will have a total resistance of about 0.4 ohms,
enough to cause degradation. An empirically derived figure of 5% of the
speaker nominal impedance is usually taken as an upper limit for cable
resistance, so for a 4-ohm speaker setup, 0.2 ohms is tops. For your 18
AWG lamp cord, that works out to about 31 feet of wire, or 15 feet of
cable. Pro rata, 30 feet for 8-ohm speakers. Longer than that, you need
heavier wire.

Regards,

Colin D.

 

[Raphael Bustin]

Pro rata, 30 feet for 8-ohm speakers. Longer than that, you need
heavier wire.

Maybe so but I can still get that at Home Despot
(as opposed to a ripoff hi-end audio store.)

I guess I've been out of the game for a while.
When did 4 ohms become the norm for speakers?


rafe b
www.terrapinphoto.com

 

[Neil Gould]

Of course. But amplifier performance has to be measured in a
repeatable manner, hence dummy loads, which while not presenting the
same conditions as a speaker, are nevertheless a standard method of
determining amplifier maximum power and THD figures.

Therein lies the difference in our opinion. You're talking about bench
testing, and I'm talking about the real world, where the performance
reduction introduced by the resistance of slightly lighter speaker wire
are dwarfed by other factors.

With *short* runs of cable, I will agree. The criterion is how much
resistance the cable interposes between the amp. and speaker. Once
the cable resistance begins to seriously degrade the damping factor,
or becomes a significant percentage of the speaker impedance, the
performance will drop.

The manner in which the performance drops is not insignificant. One can
compute the loss of amplitude introduced by the difference in resistance
between, say, 18 vs. 14 Ga. wire, but one may not be able to *hear* that
loss. Many double-blind listening tests have shown that to be true.

This may not be an actual problem with main
speakers within, say 5 or 10 feet of the amp, but surround sound
setups with rear speakers at the other end of the room, and cabling
run around the perimeter, its easy to get runs of 30 feet or more.
At that distance, lamp cord will have a total resistance of about 0.4
ohms, enough to cause degradation.

The gauge of the "lamp cord" doesn't matter??? At least in the US, "lamp
cord" describes a particular wire configuration, not its Gauge. Suppose
one is using 16 or 14 Ga. "lamp cord"?

An empirically derived figure of
5% of the speaker nominal impedance is usually taken as an upper
limit for cable resistance, so for a 4-ohm speaker setup, 0.2 ohms is
tops. For your 18 AWG lamp cord, that works out to about 31 feet of
wire, or 15 feet of cable. Pro rata, 30 feet for 8-ohm speakers.
Longer than that, you need heavier wire.

You've introduced two issues as constants; the impedance of a speaker
setup, although 4 Ohms is not typical, and 18 AWG as the weight of "lamp
cord", which I already discussed above. We don't disagree about the need
for heavier wire for longer runs, that is a well-known fact. But, even so,
such wire need not be "expensive", "large" or "fat" as in your opening
rebuttal:

"Aaahh, bad example there. Large, fat, expensive, low-resistance speaker
cable do matter, if you are running a high-end amplifier/speakers combo."

Also note that in your entire statement, there is *no* mention of the
length of the run, the effiiciency of the speaker, or any of the other
factors that impact performance, only a blanket tirade against "lamp
cord", all of which lead me to the idea that you're one of those folks
that think that if one pays 10x the value of a piece of wire, they'll hear
the difference.

Regards,

Neil

 

[Colin D]

Therein lies the difference in our opinion. You're talking about bench
testing, and I'm talking about the real world, where the performance
reduction introduced by the resistance of slightly lighter speaker wire
are dwarfed by other factors.

The manner in which the performance drops is not insignificant. One can
compute the loss of amplitude introduced by the difference in resistance
between, say, 18 vs. 14 Ga. wire, but one may not be able to *hear* that
loss. Many double-blind listening tests have shown that to be true.

The gauge of the "lamp cord" doesn't matter??? At least in the US, "lamp
cord" describes a particular wire configuration, not its Gauge. Suppose
one is using 16 or 14 Ga. "lamp cord"?

You were the first to mention lamp cord, and you stated 18 AWG as well.
I simply stayed with your specification. Obviously, 14 AWG cord is
better (lower resistance per length) than 18 AWg or thinner.

You've introduced two issues as constants; the impedance of a speaker
setup, although 4 Ohms is not typical, and 18 AWG

reminder: 18 AWG was your specification, not mine.

as the weight of "lamp

cord", which I already discussed above. We don't disagree about the need
for heavier wire for longer runs, that is a well-known fact. But, even so,
such wire need not be "expensive", "large" or "fat" as in your opening
rebuttal:

"Aaahh, bad example there. Large, fat, expensive, low-resistance speaker
cable do matter, if you are running a high-end amplifier/speakers combo."

Yes, that was a quote from the original post, his words I copied in my
reply.

Also note that in your entire statement, there is *no* mention of the
length of the run, the effiiciency of the speaker, or any of the other
factors that impact performance, only a blanket tirade against "lamp
cord", all of which lead me to the idea that you're one of those folks
that think that if one pays 10x the value of a piece of wire, they'll hear
the difference.

By 'entire statement', do you mean the first post, or all my subsequent
posts? If the latter, I have certainly mentioned length, several
times. Speaker efficiency and signal source quality should be a given
at the level we are discussing; and 'tirade' is your word, from which I
deduce you are given to the use of hyperbole, since none of my posts
could remotely be called a tirade.

'hearing the difference' is very subjective, my stance all along has
been to favor measurement with instruments which show distortion, rather
than A to B hearing tests. I acknowledge that some distortion may not
be audible, or recognizable, or may even be favorable, as some music
tends to sound better to some listeners if there is some harmonic
distortion. If my distortion meters and oscilloscope show me what is
better, then I go with that, even if I can't hear any difference. At
60+ my hearing is but a pale shadow of what my grand-daughters can hear.

Of course, it depends on what one is listening to as well, a lot of the
modern pop music is so artificial, and deliberately distorted to produce
'enriching' harmonic overtones that it's pointless even playing it on
good gear. Bell wire is good enough for some of that crappola. {

Regards,

Colin D.

 

[Neil Gould]

You were the first to mention lamp cord, and you stated 18 AWG as
well. I simply stayed with your specification.

From your original post of 4/20/06:

Colin D <[email protected]> posted:
"The control over this effect by the amplifier depends on the 'looking
backwards' impedance providing an effective short from the speaker's
point of view. However, the speaker cabling is in series with the
amplifier impedance, so the cable resistance has to be very low. If
your piece of lamp cord has a resistance of, say, an ohm [...]"
^^^^^^^^
I had not made a post in this thread at that time, and it was this comment
that elicited my response. Objectivity is important!

Regards,

Neil

 

[Colin D]

You were the first to mention lamp cord, and you stated 18 AWG as
well. I simply stayed with your specification.

From your original post of 4/20/06:

Colin D <[email protected]> posted:
"The control over this effect by the amplifier depends on the 'looking
backwards' impedance providing an effective short from the speaker's
point of view. However, the speaker cabling is in series with the
amplifier impedance, so the cable resistance has to be very low. If
your piece of lamp cord has a resistance of, say, an ohm [...]"
^^^^^^^^
I had not made a post in this thread at that time, and it was this comment
that elicited my response. Objectivity is important!

Yep, I forgot that, but the intention there was to point out the
resistance, which is of course dependent on both gauge and length. You
mentioned 18 AWG, which is when I looked up the wire tables and found
the resistance.

An interesting discussion overall, which showed me how one person's
viewpoint can differ from another's over the same topic.

regards,

Colin D.

 

[Neil Gould]

You were the first to mention lamp cord, and you stated 18 AWG as
well. I simply stayed with your specification.

From your original post of 4/20/06:

Colin D <[email protected]> posted:
"The control over this effect by the amplifier depends on the
'looking backwards' impedance providing an effective short from the
speaker's point of view. However, the speaker cabling is in series
with the amplifier impedance, so the cable resistance has to be very
low. If
your piece of lamp cord has a resistance of, say, an ohm [...]"
^^^^^^^^
I had not made a post in this thread at that time, and it was this
comment that elicited my response. Objectivity is important!

Yep, I forgot that, but the intention there was to point out the
resistance, which is of course dependent on both gauge and length.
You mentioned 18 AWG, which is when I looked up the wire tables and
found the resistance.

Well, I mentioned ">= 18 AWG", and as the resistance of 18 AWG is within
your target spec of 5% for 8 Ohm nominal speakers (which are more
prevalent than 4 Ohm speakers around here), my point was that any
performance loss due to the slightly lower resistance of short runs of
larger wire are not likely to be perceptable, even in worst-cases where
speakers are relatively inefficient, given the real world factors that
impose much larger and unavoidable distortions on the sound.

An interesting discussion overall, which showed me how one person's
viewpoint can differ from another's over the same topic.

Agreed.

Best regards,

Neil