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Measurements of speaker cables in frequency and time domain

BluesDaddy

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I made an attempt to measure input impedance of 5m zipcord speaker cable with open end (no termination), with a point-by-point measurement at discrete frequencies and Excel sheet. The result looks quite realistic. There is a dip near 10MHz.

View attachment 127723
Measuring range is 100kHz - 24MHz
I confess I don't understand the relevance to audio reproduction or why I should care about measurements of speaker cable from 100 kHz to 24MHz.
 

KSTR

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I confess I don't understand the relevance to audio reproduction or why I should care about measurements of speaker cable from 100 kHz to 24MHz.
Sigh... it's been explained several times why this can be relevant.
OK, one more time for you and everybody else who hasn't read properly and then post ill-considered comments:
Not all amps are happy with an unterminated long cable and it is possible that in a cable comparison the amp has gone unstable without noticing and the sound difference has been wrongly attributed to the cable change.
 

BluesDaddy

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Sigh... it's been explained several times why this can be relevant.
OK, one more time for you and everybody else who hasn't read properly and then post ill-considered comments:
Not all amps are happy with an unterminated long cable and it is possible that in a cable comparison the amp has gone unstable without noticing and the sound difference has been wrongly attributed to the cable change.
How many amps, what are their characteristic measurements, and is approximately 15' really long enough? What would this wind up sounding like?
 

KSTR

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A typical sign of an amp (on the edge of) oscillating briefly is "harsh treble", "broken soundstage" etc.
And there are quite a few boutique amps with little or non-existent measures to make the amp 100% load-proof. In some designer circles, the required R//L output isolator is deemed detrimental for sound quality. The faster the amp the bigger the potential risk.
 

Martin

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I’m curious: Why would anyone turn on an amp “with an unterminated long cable” attached?

Martin
 

preload

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C'mon lets get some real life practical examples. Otherwise this is a bunch of "what if" theoretical jibberish.

Which commercially available amplifier will oscillate using a 10 ft length of 12 GA zip cord? Let's start there. If you can name one that would be a good starting point. If not, this is a waste of time.
 

Pdxwayne

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I’m curious: Why would anyone turn on an amp “with an unterminated long cable” attached?

Martin
If I understand correctly, this is about potential problem for the subsequent subjective listening tests, after cables were measured first unterminated. Or, potential issue for the next cable being measured.
 
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pma

pma

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At frequencies we speak about, >1MHz, the speaker load is almost the same thing as no termination of the cable, because of dominating inductance. Call it inductive load if you want, makes no difference.
 

LTig

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C'mon lets get some real life practical examples. Otherwise this is a bunch of "what if" theoretical jibberish.

Which commercially available amplifier will oscillate using a 10 ft length of 12 GA zip cord? Let's start there. If you can name one that would be a good starting point. If not, this is a waste of time.
I once borrowed a Naim power amp (could have been a NAP 250) to test with my Magnepan 1.6. On switch on the speakers screeched like hell and both amps blew the fuses in the tweeters before I could switch it off. Back it went and no more Naim for me. Got a used pair of Denon POA 6600 which were great and never failed me.

PS: speaker cables were 3m of Audioplan Musicable with about 6 square mm area.
 

preload

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I once borrowed a Naim power amp (could have been a NAP 250) to test with my Magnepan 1.6. On switch on the speakers screeched like hell and both amps blew the fuses in the tweeters before I could switch it off. Back it went and no more Naim for me. Got a used pair of Denon POA 6600 which were great and never failed me.

PS: speaker cables were 3m of Audioplan Musicable with about 6 square mm area.

I should have specified, BESIDES Naim, which we all know has issues.
 

DSJR

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I was going to post Naim as well. All through their existence, although the latest cosmetic models are better subjectively in the midrange for whatever reason, these amps have been run almost to the point of instability, although the mid to later Nait 5i's and maybe the streamers too might be better protected. I firmly believe this is one of the sonic aspects of the marque - this up-front band limited kind of presentation which even the Statement amp system exhibits - and which well off new pensioners absolutely love (I'm 64, so in that age group if not financially).
 

spacevector

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C'mon lets get some real life practical examples. Otherwise this is a bunch of "what if" theoretical jibberish.

Which commercially available amplifier will oscillate using a 10 ft length of 12 GA zip cord? Let's start there. If you can name one that would be a good starting point. If not, this is a waste of time.
One member recently had issues with Hypex based product. Documented here: https://www.audiosciencereview.com/forum/index.php?threads/amp-oscillation-issue.21771/

They fixed it by adding ferrite beads which likely added some damping and shifted the resonant frequency of the system.
 

BluesDaddy

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A typical sign of an amp (on the edge of) oscillating briefly is "harsh treble", "broken soundstage" etc.
And there are quite a few boutique amps with little or non-existent measures to make the amp 100% load-proof. In some designer circles, the required R//L output isolator is deemed detrimental for sound quality. The faster the amp the bigger the potential risk.
So, unless you're an idiot buying a "boutique amp" and using too thin cables with it you're good to go? This strikes me as like a 0.0002 % probability of occurring. All this strikes as "sound and fury, signifying nothing".
 
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pma

pma

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C'mon lets get some real life practical examples. Otherwise this is a bunch of "what if" theoretical jibberish.

C'moon I have designed and measured amplifiers and their issues for decades. That's the reason why I share my experience, because I am hoping it makes sense. Even in this thread there is an oscilloscope plot of amp oscillations with a 10m cable. If you do not want to take it serious it is all your choice and you may stuck with simplest simplified views. Your audio life will be much easier then, you can join the crowd, until you get into trouble you will not be able to explain for yourself.
BTW, share your own experience, design and measurements, if you want for me to take you serious. I am not taking purely verbal debate and argueing.
 

MarkS

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If an amp can go unstable due to the attached cable, it is (at least IMO) a bad design.

Yes, such designs should be avoided.

Until proven otherwise, I am going to assume that major manufacturers (annual sales of, say, >100M USD, a number chosen to exclude Naim) do not produce such designs.
 

Chrispy

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Thank you, Klaus.

All, I will not reply to stupid accusations and also will not go with secondary school textbook explanations. It is not my way. For those who do not like my approach, feel free to put me on the ignore list.
My apologies, but the way you wrote and did not respond to others (nor am I particularly familiar with your background)....my imagination got away from me. I've heard about the silly Naim amps before....but seems to be lacking in real world applications....
 

pjug

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I wouldn't call 16 AWG "pretty thin" over any distance less than 25 feet.
It also depends on the speaker impedance. 16 AWG is maybe on the thin side for 4 ohm speakers, but probably fine with 8 ohm speakers. I use 14 AWG with my 8 ohm speakers.
 
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