One of the woven cable type that have stood the test of four decades are the Kimber offerings. Very high capacitance and exceptionally low inductance. These need to be used with some care because as noted above some power amps cannot cope with high capacitance, and hence will go into terminal oscillation.
Now another thing that can cause issues with a power amp is RF getting back up the amp'[s loudspeaker terminals, and one of the advantages of the low inductance of a woven cable is its immunity to RF (since this couple into the inductive part of the cable's impedance).
Unusually for a loudspeaker cable's properties, the RF immunity of woven cables is measurable and verifiable.
Now another thing that can cause issues with a power amp is RF getting back up the amp'[s loudspeaker terminals, and one of the advantages of the low inductance of a woven cable is its immunity to RF (since this couple into the inductive part of the cable's impedance).
Unusually for a loudspeaker cable's properties, the RF immunity of woven cables is measurable and verifiable.
Off the top of my head I remember at least two manufacturers of stated caution. Naim Audio recommending certain length of NacA5 speaker cable else warning about oscillation problems in some of their amps. Spectral Audio asks for filter network MIT cables to optimally low pass their high speed design DC amps and avoid MHz oscillations & RFI.
The biasing system is something completely different from the network termination boxes used in MIT and Transparent cables. Plenty of diy potential in both.
Didn't mean to sound like I was coming down on Spectral, which is a really solid company, if somewhat opaque if you're trying to get a schematic to do a repair, and you absolutely will need one - lots of unmarked parts in a very elaborate circuit. Understandable from their POV; bozos from Little Rock could hardly be expected to make repairs without access to their selected parts, etc. But I certainly wouldn't be worried about their stability
An ex-CERN guy, member jneutron, made a great case for proper termination of speaker cables, recommending Zobels at the speaker end and other effort be put into above-audio-range transmissive performance. These things also improve amplifier stability. But really, if the amplifier is in danger of melting down caused by anything on the load line, its a POS design. Just say no.
All good fortune,
Chris
An ex-CERN guy, member jneutron, made a great case for proper termination of speaker cables, recommending Zobels at the speaker end and other effort be put into above-audio-range transmissive performance. These things also improve amplifier stability. But really, if the amplifier is in danger of melting down caused by anything on the load line, its a POS design. Just say no.
All good fortune,
Chris
Those who do not understand transmission line theory: Their reflection coefficient on the subject, is perhaps Rho = 1.0.
Audio amplifiers should work well at audio frequencies.
They are not meant to be AM radio transmitters, HF, VHF, or UHF transmitters either (and just try and get them to put out the 500GHz signal that I measured on my job).
Just my opinion and experience.
Audio amplifiers should work well at audio frequencies.
They are not meant to be AM radio transmitters, HF, VHF, or UHF transmitters either (and just try and get them to put out the 500GHz signal that I measured on my job).
Just my opinion and experience.
No, I am not in the market for a new amp. I was just surprised that at the end of a really technical article there was a line that actually gave some credence to the idea that speaker cables can make a difference wits some amplifiers. I was asking this forum to expand on what was said so I have a better idea of what is going on.
Ahhh.... Humans.... I'm always amazed by how someone will take a sentence or sentence fragment from a website or forum post written years ago, possibly late at night after a beer or two just trying to wrap up that bloody page, remove all context and conclude something from it.
An amplifier with poor stability will be particularly sensitive to capacitive load. Speaker cables present a capacitive load to the amp, so an amp that's marginal on stability (low phase margin and/or gain margin) will be more sensitive to long speaker cables than an amp that operates with a higher PM/GM.
Fancier cable tends to have higher capacitance. The Goertz line of cables immediately spring to mind. The MI-series is basically a long plate capacitor. These will likely push an amp with marginal stability closer to instability than plain zip cord of the same wire gauge. But that's not always the case. I recall the Monster cable of the 1990s – the "oxygen-free" stuff that corroded from the chlorine in the PVC jacket. That cable had a spacer between the two conductors, thus, would be less capacitive than comparable zip cord, hence, easier for an amp with marginal stability to drive.
Do speaker cables matter? Absolutely! Without them no current will flow from the amp to the speakers and no sound will be produced. There. Now someone ten years from now can take that line out of context and claim that fancy cables matter because I said speaker cables matter...
Tom
An amplifier with poor stability will be particularly sensitive to capacitive load. Speaker cables present a capacitive load to the amp, so an amp that's marginal on stability (low phase margin and/or gain margin) will be more sensitive to long speaker cables than an amp that operates with a higher PM/GM.
Fancier cable tends to have higher capacitance. The Goertz line of cables immediately spring to mind. The MI-series is basically a long plate capacitor. These will likely push an amp with marginal stability closer to instability than plain zip cord of the same wire gauge. But that's not always the case. I recall the Monster cable of the 1990s – the "oxygen-free" stuff that corroded from the chlorine in the PVC jacket. That cable had a spacer between the two conductors, thus, would be less capacitive than comparable zip cord, hence, easier for an amp with marginal stability to drive.
Do speaker cables matter? Absolutely! Without them no current will flow from the amp to the speakers and no sound will be produced. There. Now someone ten years from now can take that line out of context and claim that fancy cables matter because I said speaker cables matter...
Tom
Years ago, I had access to a $50,000 Rohde & Schwarz Vector Network Analyzer, and a $10,000 Precision Open/Short/Load Calibration Kit.
I tested a 'lowly' 18 gauge zip cord, and a 12 gauge Monster cord.
I measured the cords for these conditions: open at the far end; short at the far end; a non inductive 8 Ohm resistive load at the far end.
The measurements included insertion loss; inductance (when shorted at the far end); capacitance (when open at the far end); and Frequency response (non inductive 8 Ohm resistive load at the far end).
I hate to say it, but I concluded that both of those cords would work very well in my stereo systems (25 foot lengths, and the average 8 Ohm speaker with minimum impedance that is not less than 4 Ohms).
Your measurement results may vary.
Your listening results may vary.
I tested a 'lowly' 18 gauge zip cord, and a 12 gauge Monster cord.
I measured the cords for these conditions: open at the far end; short at the far end; a non inductive 8 Ohm resistive load at the far end.
The measurements included insertion loss; inductance (when shorted at the far end); capacitance (when open at the far end); and Frequency response (non inductive 8 Ohm resistive load at the far end).
I hate to say it, but I concluded that both of those cords would work very well in my stereo systems (25 foot lengths, and the average 8 Ohm speaker with minimum impedance that is not less than 4 Ohms).
Your measurement results may vary.
Your listening results may vary.
Why hate to say it? It's not a surprise that both would work well. Good to hear that measurements agreed with theory.
Listening results will vary. The variation may not be correlated with the stimulus that reaches the ears of the listener. After all, humans are humans.
Tom
Don't know if this is helpful to anyone. I've heard a system with a Benchmark AHB2 driving Spendor towers where the speaker cables noticeably mattered to the sound. Braided Kimber cables left us feeling like the amp was fighting to figure out how the speakers were reacting, resulting in missing midrange and a generally constrained sound. Relatively cheap Blue Jeans speaker cables made out of 12 gauge Belden 5000 series wire didn't have this issue, the sound with them was free, fast and had tons of air.
There is an excellent text called "Loudspeakers, for Music Recording and Reproduction", by Philip Newell (a guy who designs and installs studio systems, mixing desks etc http://philipnewell.net/ ) and Keith Holland, (who works at the Institute of Sound and Vibration Research at Southampton University https://www.southampton.ac.uk/vaae/about/staff/krh_kholland.page ). Two more hard bitten audio systems professionals would be hard to find.
Chapter 6 is "Effects of Amplifiers and Cables", with section 6:10 being "Some provable characteristics of cable performance" from the results of a paper presented at the Institute of Acoustics.
It is an interesting read, and suggests that interaction of an amplifier, the cable, and a real world loudspeaker impedance is not as straightforward as might be imagined.
I alas cannot find a pdf version on line; I have the hardback book in front of me.
Chapter 6 is "Effects of Amplifiers and Cables", with section 6:10 being "Some provable characteristics of cable performance" from the results of a paper presented at the Institute of Acoustics.
It is an interesting read, and suggests that interaction of an amplifier, the cable, and a real world loudspeaker impedance is not as straightforward as might be imagined.
I alas cannot find a pdf version on line; I have the hardback book in front of me.
A lot of amplifiers have been built with insufficient phase margin or insufficient HF impedance isolation because builders are always pushing the feedback to the limit in order to achieve the most impressive specs. Many are never analyzed and tested except to see that they are stable on the bench and/or with short cables. Even some big names like Yamaha have made amplifiers that are known to be unstable with long cables. If you buy an "audiophile" product, expect it to be unstable and unreliable.
I don't have my Cordell right at hand, but I believe that he also mentions terminating at the speaker terminals with Zobel.
I'm reminded of a doctor's wife I worked for in college. I was an independent computer consultant. I was fixing something or another, and suddenly she comes out with, "What are all these wires for? Could you just cut them off, and get rid of them?"
I replied, "That could be detrimental to performance. But I have an idea." So, I bought about $16 worth of flexible plastic tubing with a slice all along it, so it could be filled with wires.
I put all the wires in a few of those tubes. She was so relieved!
She dumped her purse out on the table, and gave me all the cash she had, which was ~$1000. I tried not to laugh. But it was literally one of the high points of her life!
As far as capacitance and inductance in speaker cable, it is mostly due to the "skinning effect" of AC current. Power transmission lines are not solid copper, because 60 Hz. AC travels only on the outer part of the conductor. Those cables need the strength of steel cores, where there is no current flow anyway.
The higher the frequency, the closer to the outside edge of the conductor the current will flow.
When you take 16 awg lamp cord, capacitance builds between the two conductors with insulation as the dielectric. And the same with inductance. The two wires induce each other. If you keep the two wires at some distance, you don't get those problems. Twisted pair is the absolute worst for capacitance and inductance.
In CATV coax, RG6, the center conductor is copper plated. At those frequencies, all the signal travels on the surface of the conductor. AC at 15kHz is much more affected by a few pF of capacitance floating around than DCV. If anyone sticks with the sound principles of electrical engineering--electricity follows a very predictable mathematical model.
I work with uOhm and nV level signals inside 75kV power supplies! If you end up with a large phase angle between apparent and real power, it wreaks havoc on optocouplers that isolate IGBT gate drivers from the gates themselves. In certain cases small DC-powered parts, such as cooling fans, comm circuitry, the devices have tiny inverters behind the DC input, simply to enable PFC.
There is a lot of superstition at work in audio. It begins with a sound scientific principle, progresses to severe misuse of the principle until it is unrecognizable, and from there it becomes doctrine of a faith-based belief-system. This is due to a human tendency fostering the notion that, if an individual can uncover the right information, forever after he will obtain worthwhile results without investment of time, effort or money.
One of my all-time favorites is cryogenic cooling of copper conductors, because it aligns the copper 'crystals' in a much more efficient arrangement for carrying electrical signals. And that is absolutely factual. So, several manufacturers touted cryogenically cooled speaker cable, with efficiently aligned copper crystals.
This is what keeps the ancient maxim alive, "There are obvious limits to human intelligence, but none whatsoever on stupidity!" In order for that principle to be effective, the cables need to remain cryogenically cooled. When the copper warms up, it just goes back the way it was.
I have three hifi audio systems. They all have glaring weak points. One I use a 60Wx2 Rotel integrated amp, 8" JBL sub, and two very high quality Finnish satellite speakers. those have 1/4-20 mounting holes. So, I put some anchors in the concrete wall with bare 1/4-20 threads on the ends. On those I put $20 tripod ball heads, and put the speakers on the ball heads.
I can literally aim them anywhere. But the CD transport is a 5-1/4" PC CD/DVD R-RW. I'm working on that part. The one on the third floor is essentially the same, with a laptop sound card plugged into the CD input on a Rotel 60Wx2. The third is in many pieces that may never be reassembled, because I got that equipment in the 80s.
I replied, "That could be detrimental to performance. But I have an idea." So, I bought about $16 worth of flexible plastic tubing with a slice all along it, so it could be filled with wires.
I put all the wires in a few of those tubes. She was so relieved!
She dumped her purse out on the table, and gave me all the cash she had, which was ~$1000. I tried not to laugh. But it was literally one of the high points of her life!
As far as capacitance and inductance in speaker cable, it is mostly due to the "skinning effect" of AC current. Power transmission lines are not solid copper, because 60 Hz. AC travels only on the outer part of the conductor. Those cables need the strength of steel cores, where there is no current flow anyway.
The higher the frequency, the closer to the outside edge of the conductor the current will flow.
When you take 16 awg lamp cord, capacitance builds between the two conductors with insulation as the dielectric. And the same with inductance. The two wires induce each other. If you keep the two wires at some distance, you don't get those problems. Twisted pair is the absolute worst for capacitance and inductance.
In CATV coax, RG6, the center conductor is copper plated. At those frequencies, all the signal travels on the surface of the conductor. AC at 15kHz is much more affected by a few pF of capacitance floating around than DCV. If anyone sticks with the sound principles of electrical engineering--electricity follows a very predictable mathematical model.
I work with uOhm and nV level signals inside 75kV power supplies! If you end up with a large phase angle between apparent and real power, it wreaks havoc on optocouplers that isolate IGBT gate drivers from the gates themselves. In certain cases small DC-powered parts, such as cooling fans, comm circuitry, the devices have tiny inverters behind the DC input, simply to enable PFC.
There is a lot of superstition at work in audio. It begins with a sound scientific principle, progresses to severe misuse of the principle until it is unrecognizable, and from there it becomes doctrine of a faith-based belief-system. This is due to a human tendency fostering the notion that, if an individual can uncover the right information, forever after he will obtain worthwhile results without investment of time, effort or money.
One of my all-time favorites is cryogenic cooling of copper conductors, because it aligns the copper 'crystals' in a much more efficient arrangement for carrying electrical signals. And that is absolutely factual. So, several manufacturers touted cryogenically cooled speaker cable, with efficiently aligned copper crystals.
This is what keeps the ancient maxim alive, "There are obvious limits to human intelligence, but none whatsoever on stupidity!" In order for that principle to be effective, the cables need to remain cryogenically cooled. When the copper warms up, it just goes back the way it was.
I have three hifi audio systems. They all have glaring weak points. One I use a 60Wx2 Rotel integrated amp, 8" JBL sub, and two very high quality Finnish satellite speakers. those have 1/4-20 mounting holes. So, I put some anchors in the concrete wall with bare 1/4-20 threads on the ends. On those I put $20 tripod ball heads, and put the speakers on the ball heads.
I can literally aim them anywhere. But the CD transport is a 5-1/4" PC CD/DVD R-RW. I'm working on that part. The one on the third floor is essentially the same, with a laptop sound card plugged into the CD input on a Rotel 60Wx2. The third is in many pieces that may never be reassembled, because I got that equipment in the 80s.