Speaker cable dilemma

[Audiophile Heretic]

And, not to mention what you stated, it is for a single conductor coil, not close parallel cable with opposite direction of signal flow.

I am willing to accept when I am wrong. It inspires me to learn more. Is the coil unimportant because of the close parallel wires with opposite current flow? Is the coil with close parallel wires a 1:1 transformer?

 

[Speedskater]

No.
It's just a coiled speaker cable.
* * * * * * * * * * * *
Now if you could find some 'Figure 8' zip-cord with widely spaced conductors, like old 300 Ohm TV antenna twin-lead. And carefully glued the coil together with no twisting, there would be added inductance.

 

[3db]

This subject has been clobbered to death. Good learning curve for an audiophyte.

 

[mtrycrafts]

I am willing to accept when I am wrong. It inspires me to learn more. Is the coil unimportant because of the close parallel wires with opposite current flow? Is the coil with close parallel wires a 1:1 transformer?

In a transformer there is no current flow in the opposite direction of the adjacent wires, all goes in the same direction.
Google might show images and how and even a 1:1 transformer.
Speaker wires coiled is not a transformer become.

Think of the voice coil in a speaker winding, single wire creates a field to interact with the magnet.
You wrap a speaker wire, cone would not move, fields are canceled.

 

[Speedskater]

The 'mtrycrafts' answer is correct.
In a coiled speaker cable, it's about the same current moving in opposite directions and cancelling.
In a crossover, it's about coils carrying different currents.

 

[highfigh]

I have heard this weak argument before. This subject has been clobbered to death by whom? I was not part of that discussion, why would I know about it? What was the agreed result of the discussion? What was the recognized expertise of the participants?

Scientific fact is not a consensus of opinion of amateurs.

It has been clobbered to death by the whole world. This BS started in the early-'80s and it's all because of marketing.

The fields of the signal don't cancel, but the common mode noise, if there is any, does.

You wrote "Is there not series inductance in speaker wire?" It shouldn't have much, if any inductance of its own but that's easy enough to test.

 

[highfigh]

I am willing to accept when I am wrong. It inspires me to learn more. Is the coil unimportant because of the close parallel wires with opposite current flow? Is the coil with close parallel wires a 1:1 transformer?

It's a coil, not a transformer, which isolates the primary winding from the secondary. If anything, it could be similar to a choke, but the winding would need to be much tighter.

A loose coil doesn't do much to impede low frequencies.

 

[mtrycrafts]

The 'mtrycrafts' answer is correct.
In a coiled speaker cable, it's about the same current moving in opposite directions and cancelling.
In a crossover, it's about coils carrying different currents.

Yes.
The coil in a crossover is a single wire wound enough to get the design inductance needed.
Same with a transformer where the number of coils in the primary is compared with a secondary to determine the ratio of energy, voltage being transferred.
The coil in a speaker is a single wire as well interacting with the mag field, in either direction.

 

[3db]

I have heard this weak argument before. This subject has been clobbered to death by whom? I was not part of that discussion, why would I know about it? What was the agreed result of the discussion? What was the recognized expertise of the participants?

Scientific fact is not a consensus of opinion of amateurs.

Like I said before, clobbered to death!!

As an EE retired, I'm very well aware of scientific fact verses audiophile subjective opinions. Should I go on?

 

[mtrycrafts]

Like I said before, clobbered to death!!

... Should I go on?

Yes, please.

 

[highfigh]

As EEs, you all know that all cable has a characteristic impedance made up of series resistance, series inductance, and parallel capacitance.

Rather than just arguing about this, lets prove a hypothesis with some simple experiments.

Take a significant length of speaker wire. Load it with a resistor, say 8 ohms. Lay the wire out straight. Measure the inductance. Coil the wire up. Measure the inductance again. Is there a significant change in inductance?

Take one of the wires of the pair, connect it to an AC source. If you use your audio amplifier as the AC source, you better load the circuit with a series resistor, say 8 ohms 10 watts. Lay the wire out in one big loop. Drive the wire with a signal. Measure the voltage on the other wire of the pair. Coil the wire into a smaller loop. Measure the voltage on the other wire of the pair. Can you measure the signal on the non-driven wire? Is there a change in voltage between one big loop of wire and coiled wire? Try this for different audio frequencies. Does the current in one wire induce a current in the other wire?

I have AA Engineering Science and AAS Electronic Technology with academic honors and PTK, but I am a heretic. Your degrees and audiophile rhetoric mean nothing to me. Show me your proof.

I also don't have access to the equipment needed to perform these experiments myself.

Measurable inductance and capacitance in a speaker cable makes it unusable and if you haven't measured the differences after your wire loop examples, do that, then tell us how much difference it makes and whether it affected the frequency response, phase, etc.

Current in a conductor creates a magnetic field, but in most audio applications, the current in the speaker wire is low and it won't make a difference that matters.

Have you ever thought that listening to the music is the point of this, rather than details that may not be audible?

If his degrees that are more advanced than yours don't matter, why did you bother to post yours?

 

[Speedskater]

As EEs, you all know that all cable has a characteristic impedance made up of series resistance, series inductance, and parallel capacitance.

That would be the 'Radio Frequency Characteristic Impedance'. It only matters when the cable is a significant fraction of a wavelength long. At audio frequencies, that would be for cables that are several thousands of feet long. Also the common short form formula that is often used, only applies at frequencies well above 100 kilohertz.

 

[Speedskater]

Of course, a two conductor cable as inductance! It's a major part of 'Radio Frequency Characteristic Impedance'.
But winding that cable in a coil, won't change the total cable inductance.
* * * * * * * * * * *
A long speaker cable with high total inductance, might roll off the very high tweeter response of a loudspeaker that has a very low speaker impedance at high frequencies (think Apogee) by a dB or two.
* * * * * * * * * * *
Typically speaker cables with widely spaced conductors, will have higher inductance per length than those with closely spaced conductors.
Typically speaker cables with widely spaced conductors, will have lower capacitance per length than those with closely spaced conductors.

 

[Speedskater]

All two conductor (or more) cables have measurable inductance and capacitance (and resistance).
A single straight wire has inductance and resistance. (much more inductance than a cable)(capacitance is measured between two things)
* * * * * * * * * *
the longer length of two conductor cable has increased resistance, inductance, and capacitance because of the length, regardless of form
TRUE, all the total values increase with longer length.
But the 'Radio Frequency Characteristic Impedance' stays the same regardless of length.

 

[Speedskater]

When we measure cable inductance, we jumper the two conductors together at the far end. Then measure loop inductance.

 

[highfigh]

Gene DellaSala measures the series inductance and parallel capacitance of speaker cables. Are all speaker cables unusable? How does that work?

I admit, I don't have access to the instruments to measure the inductance of speaker cables. Gene DellaSala does. Do you?



100W into 8Ω is 3.5A. 3.5A is low current? 1W into 8Ω is 350mA. How high does the current have to be to have mutual inductance between parallel conductors in speaker wire that matters?

Electromagnetic energy consists of an electric field perpendicular to a magnetic field. No magnetic field, no transfer of energy. Examples of an electrical field with no magnetic field are: a battery not in a circuit, or an amplifier with an input signal but no speaker or other load connected.



Never did I state that the inductance of a coil of 36 feet of speaker is audibly significant, because I don't know. I hypothesize the inductance goes up when the speaker wire is coiled rather than straight, and I still hypothesize that it is true because no one yet has proved to me that it is not true.

I believe that the presence of currents flowing in opposite directions in the parallel wires do not cancel the mutual inductance between wires, contrary to what mtrycrafts said.

Do you accept concepts that you believe are not true because they are not audible?

In a previous post, you said: "the fields of the signal don't cancel". That is contrary to what mtrycrafts said. You agree with me!



3db contributed nothing to the discussion. They only stated that they are a retired EE. That doesn't convince me of anything.

Really? "This has been clobbered to death by the WHOLE WORLD"? Except me, of course. Show me some references at least. If 3db has an EE, surely they must have written some research papers or proper lab reports in the process of getting their degree. They should know how to prove a scientific concept. Maybe I win an argument with more exclamation points!!!!!

Where has mutual inductance of parallel conductors with opposing currents ever been a marketing concept?

I was unable to find anything about inductance in coiled speaker wire by searching Audioholics. Where has this been "clobbered to death"?

Read "Calculating Inductance of Speaker Cables" by Gene DellaSala - August 29, 2004 www.audioholics.com/audio-video-cables/calculating-cable-inductance-of-zip-cord. Mutual inductance between parallel conductors contributes to speaker cable inductance, even though the current in the wires flows opposite directions.

I respect Gene DellaSala, not just because he has an EE degree. He proves his statements with measurements or by explaining concepts consistent with accepted scientific theory.

You answered your first question before you asked. BTW- an LCR meter isn't expensive- if you want to see how low the inductance/capacitance and resistance of speaker cable is, drop the $25 and buy one.

First, the current isn't constant. Second, it's AC, so the wire is easily able to handle 3.5A,@8 Ohms, but it's also able to handle the 7A@4 Ohms. Look at a power wire chart that's used for car audio or think about the power in a house's electrical service- 14 ga is used for 15A circuits and audiopiles recommend using wire that's larger than 10ga, even though the power is intermittent.

WRT mutual inductance- how did we ever get by before people recommended large speaker wire? Look at old audio equipment, including speakers- if you see heavy gauge wire, I'll be very surprised. Back in the old days of the 1970s, we used 18 ga and we liked it! It worked, but the amplifier power was usually lower than 100W and in higher power applications, we used heavier gauges. High powered PA systems for large venue FOH use even heavier gauge speaker cables, but I have NEVER heard anyone whop works in that industry blathering on about mutual inductance/capacitance and the other crap audiopiles are obsessed with. I know people who own recording studios- they don't talk about it unless they're being paid by someone for an ad.

You wrote "Never did I state that the inductance of a coil of 36 feet of speaker is audibly significant" in one comment- if it's not significant, what's the point of going on and on about it?

You're looking for distinctions without differences.

I have seen/heard instances when mutual inductance caused bad problems, but only in a 70V system where people had basically braided the various types of cabling over a ceiling because they didn't bother to separate them or care that their sloppy installation could make life difficult for someone else much later. I have worked in audio installation for more than 40 years and the recommendations for best practice have been "maintain separation between AC power wiring and low voltage signal cabling, especially if they're parallel. If they're not parallel, they should cross at a right angle, or close to it, in order to prevent that mutual induction. In practice, speaker wires are frequently bundled with other low voltage wiring and unless something is operating a relay or is controlled by a make/break switch, voltage spikes aren't caused by anything in those bundles but that doesn't mean spikes, buzz and hum can't be a problem. In large installations, including huge homes, it's not unusual to see a room with hundreds of feet of low voltage cabling, whether cleanly bundled and separated by type, or not. In a rack, it's impossible to separate cables by large distances and they don't usually have problems although it's not uncommon to see equipment with the power inlet and cords laced on one side and all of the rest of the cabling laced along the opposite rail, often along the lower edge of the shelves or on lacing bars that are at a right angle to the power cords that are aligned vertically on the side.

Did you think about the speaker wires being twisted in the jacket?

As far as 'clobbered to death by the whole world, get a sense of humor but also, look at the users on forums- do you really think they're all in one country?

 

[3db]

I am skeptical about your answer.

The coils in a passive crossover must be mounted perpendicular to each other so that they don't induce currents in each other, and they are all carrying currents individually.

The coils in the speaker wire are concentric. What is a transformer? A transformer is coils of wire that share a common magnetic field. The current of one induces current in the other. If you wrap speaker wire, the magnetic fields would oppose each other, but not necessarily cancel. The currents in the speaker wire that opposing magnetic fields induce would oppose each other. That sounds like the definition of back-EMF to me.

Is there not series inductance in speaker wire? The current in a wire generates magnetic fields that encircle them according to the right- hand rule. The currents in parallel speaker wires oppose each other and generate magnetic fields that oppose each other.

Opposing current flow and opposing magnetic fields does not mean there is no mutual inductance. The motion of the speaker voice coil relative to the magnet generates a current in the voice coil opposing the amplifier current, the back-EMF. The back-EMF can be seen as the low frequency resonance peak of the speaker impedance curve. The bass-reflex enclosure resonance is tuned to damp the speaker resonance motion, creating a dip in the low frequency resonance impedance peak. All electric motors have back-EMF.

You will need to come up with a better explanation to convince me.

Distributed impedance is what you are talking about and is inherent in every cable. However, these effects only come to play at radio frequencies and not at audio frequencies. I did a calculation of how long a 16 gauge cable has to be at 20KHz for it to affect signal propagation and it turns out to be something in the vicinity of 4 km. I do not think there is anyone with 4 km of speaker cable attached between the speakers and the amp outputs.

Your back emf arguement is simply a strawman argurment and nothing more.

 

[Audiophile Heretic]

Distributed impedance is what you are talking about and is inherent in every cable. However, these effects only come to play at radio frequencies and not at audio frequencies. I did a calculation of how long a 16 gauge cable has to be at 20KHz for it to affect signal propagation and it turns out to be something in the vicinity of 4 km. I do not think there is anyone with 4 km of speaker cable attached between the speakers and the amp outputs.

Your back emf arguement is simply a strawman argurment and nothing more.

Thank you for your clarification of distributed impedance.

I have not been arguing that inductance is increased in a coil of speaker cable. I have been asking skeptical questions because I was trying to understand and didn't agree with some of the explanations. Rather than insisting that I was correct, I was trying to determine what is correct.

Has anyone noticed that not all of the of the replies agree with each other? Has anyone noticed that some of the replies from the same posters contradict themselves?

I didn't expect a kind of Spanish Inquisition. Forgive me that I didn't have the blind faith required to be an Audioholic. I will not post any more questions on Audioholics forums. I will accept anything that I read on Audioholics forums without question. Everyone else is a genius and I am an idiot.

 

[Speedskater]

Note that in our posts, the word "wire" suggests one conductor and the word "cable" suggest both conductors.

 

[Audiophile Heretic]

Note that in our posts, the word "wire" suggests one conductor and the word "cable" suggest both conductors.

Thank you for your clarification of difference between wire and cable. I had not been taught that. I will use that terminology from now on.