Technical discussion on loudspeaker cable

MikeG

Member
2005-05-30 2:51 pm
a
I don't want to open up yet another thread of unsubstantiated opinions on whether this or that cable sounds better. There are already pages and pages of posts like that, and clearly some people are in the 14 gauge zipwire camp and others are convinced they got good value with their pricey stuff.

I'll admit I'm in the former camp, based on measurement. Before hooking up my speakers I tested a bunch of cables from bell wire (yes, solid core 0.6mm) through to QED OFC cable (sorry don't have a part number, borrowed it) on a Wayne Kerr Bridge Analyser, which is good to the last nH and mOhm. The results suggest that the only impedance large enough to have a significant effect is resistance, and that the resistance is exactly what you'd expect it to be given the cross sectional area of the conductor, from d.c. to 30kHz.

I have a degree in Electronics and work in Radio, and hence am well aquainted with impedance matching, capacitace, inductance, cross coupling etc. Skin effect is real and measurable - at radio frequencies. But I can't see how any of these are large enough at audio to impact any half decent amp. If there is nothing measureable at 300kHz (the limit of the Analyser) then it is difficult to argue it makes a difference.


What I'd like is for the *engineers* out there to explain what it is about their expensive cable, in electrical terms, that made it worth the money? How does 10's pF of loading have an effect when the speaker crossover contains 10uF? What circuit simulation could I run that even shows a theoretical advantage?


p.s. The measurements matched the listening tests. High resistance thin cable killed the bass, but QED and 15A ring mains Twin and Earth sounded the same. I used latter, £10 total from Wickes. :)
 

soongsc

Member
2005-03-26 2:31 pm
Taiwan
I keep getting logged off in the middle of typing. Anyone know why?

I got the AlphaCore Python for the following reasons:

1. Solid core minimizes conductor length differences associated with multi-conductor cables.

2. The conductors are closer together than other cables, thus minimizes the magnetic induced current interaction caused by difference in induced magnetic fields caused by opposit current direction.

3. Taking into consideration skin depth at different frequencies, the conductor thicknes is such that impedance is constant throughout the audion range.

I would have gotton the silver version, but did not want to spend such $$$ until I confirm the effects are audible. I did not have very good speakers at the time.

Hope this discussion does not get emotional.
 

SY

diyAudio Moderator Emeritus
2002-10-24 10:19 pm
Chicagoland
www.SYclotron.com
The crossover "contains" 10uF, but it's not shunted directly across the amp terminals.

Do not forget that many amplifiers out there which are popular with the audiophile set have distinctly twitchy characteristics regarding source impedance and stability. In the early days of "high end" speaker cable, I remember seeing certain amp/speaker cable combinations show a definite measurable difference involving bangs and smoke. Amplifier nonideality has to be factored into any simulation.

jneutron has some hypotheses about how certain measurable variables can influence localization; I expect he'll be popping in to this thread at some point.
 

soongsc

Member
2005-03-26 2:31 pm
Taiwan
I don't think any circuit simulation would properly simulate the situation because the models are not perfect, and we always measure electrical properties in a macro level. You would probably need s super computer to simulate at a the micro level if you can get it modelled correctly.
 

soongsc

Member
2005-03-26 2:31 pm
Taiwan
SY said:
The crossover "contains" 10uF, but it's not shunted directly across the amp terminals.

Do not forget that many amplifiers out there which are popular with the audiophile set have distinctly twitchy characteristics regarding source impedance and stability. In the early days of "high end" speaker cable, I remember seeing certain amp/speaker cable combinations show a definite measurable difference involving bangs and smoke. Amplifier nonideality has to be factored into any simulation.

jneutron has some hypotheses about how certain measurable variables can influence localization; I expect he'll be popping in to this thread at some point.

I think the starter wanted more engineering terms and why we purchase expesive cables. It would be interesting to know specifically which combinations yielded measurable differences so that engineers can try to figure out what's going on that creats such differences.
 

soongsc

Member
2005-03-26 2:31 pm
Taiwan
MikeG said:


I'll admit I'm in the former camp, based on measurement. Before hooking up my speakers I tested a bunch of cables from bell wire (yes, solid core 0.6mm) through to QED OFC cable (sorry don't have a part number, borrowed it) on a Wayne Kerr Bridge Analyser, which is good to the last nH and mOhm. The results suggest that the only impedance large enough to have a significant effect is resistance, and that the resistance is exactly what you'd expect it to be given the cross sectional area of the conductor, from d.c. to 30kHz.

I have a degree in Electronics and work in Radio, and hence am well aquainted with impedance matching, capacitace, inductance, cross coupling etc. Skin effect is real and measurable - at radio frequencies. But I can't see how any of these are large enough at audio to impact any half decent amp. If there is nothing measureable at 300kHz (the limit of the Analyser) then it is difficult to argue it makes a difference.


What I'd like is for the *engineers* out there to explain what it is about their expensive cable, in electrical terms, that made it worth the money? How does 10's pF of loading have an effect when the speaker crossover contains 10uF? What circuit simulation could I run that even shows a theoretical advantage?


p.s. The measurements matched the listening tests. High resistance thin cable killed the bass, but QED and 15A ring mains Twin and Earth sounded the same. I used latter, ?0 total from Wickes. :)

MikeG,

I am interested in knowing the following about your tests:

1. What signal amplitude did you use during the test?
2. What kind of load and driving source you used?
3. Did you do both phase and amplitude tests?
4. What kind of test signal did you use?
 
Re: Cables don't really matter that much

interestedinTL said:
I'm somewhat new to this forum but I've had ears a while and I've hardly ever noticed a difference in cables (other than twisted rca's in cars).

Many people have referenced this but check http://www.theaudiocritic.com then go to sample articles they have a good blurb about cable myths and what not.


The ear thing is subjective, can could get personal. I propose we try to stick to engineering terms to figure this out and see if there is a true relationship.

MikeG called for "engineers" if I remember correctly.

MikeG, where are you?
 
If you're after engineer's opinions/measurement data on audio cables you're looking for them in the wrong place. Speaking as an engineer, I can tell you that very few engineers spend their time lurking around internet audio forums, especially those that often prove hostile to engineers because their education and experience are often viewed as having spoiled their audio sensibilities.

Even fewer engineers spend any time testing audio cables, so if you're looking for measurement data, you won't find much. Why is that?

I suspect few engineers have access to expensive cables. Their education has spoiled their audio sensibilities to the point where they regard audio cables as trivialities. Most of my engineer friends who have seen ads for expensive cables regard them as humorous.

Few have access to the type of test instruments that might detect differences in cable properties. Fewer still would know how to use those instruments.

My advice? Don't hold your breath until an engineer posts some test data on expensive cables...

I_F
 
I_Forgot said:
If you're after engineer's opinions/measurement data on audio cables you're looking for them in the wrong place. Speaking as an engineer, I can tell you that very few engineers spend their time lurking around internet audio forums, especially those that often prove hostile to engineers because their education and experience are often viewed as having spoiled their audio sensibilities.

Even fewer engineers spend any time testing audio cables, so if you're looking for measurement data, you won't find much. Why is that?

I suspect few engineers have access to expensive cables. Their education has spoiled their audio sensibilities to the point where they regard audio cables as trivialities. Most of my engineer friends who have seen ads for expensive cables regard them as humorous.

Few have access to the type of test instruments that might detect differences in cable properties. Fewer still would know how to use those instruments.

My advice? Don't hold your breath until an engineer posts some test data on expensive cables...

I_F

James Moir did an extensive measurement of speaker cables, examining such things as the cable impedance effects on electrical and acoustic distortion. His conclusion:

"The initial assumption that speaker wiring has a relatively simple job to perform appears justified. The practical requirements appear to be easy to satisfy: the DC resistance of speaker cable should not exceed about 5% of the nominal impedance of the speaker system. None of the other electrical characteristics of the cable appear to be of any real significance, though cables of high self-capacitance are suspect without confirmatory evidence being available."

James Moir, Hi-Fi News & Record Review, May 1979 (!):

Jan Didden
 
I_Forgot said:
[snip]Speaking as an engineer, [snip]I suspect few engineers have access to expensive cables. Their education has spoiled their audio sensibilities to the point where they regard audio cables as trivialities. Most of my engineer friends who have seen ads for expensive cables regard them as humorous.[snip]I_F


I_F,

Not wanting a pointless discussion - I really want this thread to stay on course - but you have me confused. Are you speaking as an engineer or an audiophile? Are YOUR 'audio sensibilities' also spoiled, or are you the proverbial exception that confirms the rule? Where do you stand?

Jan didden
 

soongsc

Member
2005-03-26 2:31 pm
Taiwan
In the beginning.

MikeG said:
I don't want to open up yet another thread of unsubstantiated opinions on whether this or that cable sounds better. There are already pages and pages of posts like that, and clearly some people are in the 14 gauge zipwire camp and others are convinced they got good value with their pricey stuff.



What I'd like is for the *engineers* out there to explain what it is about their expensive cable, in electrical terms, that made it worth the money? How does 10's pF of loading have an effect when the speaker crossover contains 10uF? What circuit simulation could I run that even shows a theoretical advantage?



I sense the start of a mess. It would be interesting to see what comes up in the next few weeks.
:D :xeye: :rolleyes: :eek: :confused: :bigeyes: :clown: :dead: :whazzat: :cannotbe: