Calling Gene and other EE.. Need your help on effects of cables on signal propogation.

[3db]

There appears to be a study done that shows that even short cables interact with speakers to produce noise; https://www.eetimes.com/loudspeakers-effects-of-amplifiers-and-cables-part-5/

My counter arguement stems from this https://www.allaboutcircuits.com/textbook/alternating-current/chpt-14/long-and-short-transmission-lines/ where speaker cables are considered electrically short so there should be no difference spectral or other wise between the amps output terminals and the speaker terminals. No where in the first article did this study indicate explicitly or implicitly that measurements were taken at the same time between the amps output terminals and the speaker terminals.

 

[ryanosaur]

Please chime in @gene . This would be cool to hear your thoughts on!

 

[Replicant 7]

Gene sleeping!!! Lol he stays up to the wee hours in the morning.
Please tell me that article is bonkers! Short speaker cable introduce noise into the speakers?;

 

[lovinthehd]

@3db did you also start a thread like this over at audiosciencreview? You should....

 

[3db]

@3db did you also start a thread like this over at audiosciencreview? You should....

Just did under general.

 

[3db]

What wasnt explained was the nature of the signal, the type of speaker and how the measurements were taken. If the measurements of input and output taken were not synchronized in time in a window small enough to capture say, twice that of highest frequency, ie 20KHz, then this could explain the discrepancy and why we are seeing different signal composition at the amplifier output and the speaker terminal inputs. There is no insertion loss of the cable that is seen by the amplifier. The resistance of the 6m cable is 0.035 ohms so the effects of a voltage divide caused by wire is nill.

 

[highfigh]

I want to see more about "The measurements were taken in a city-centre office with typical city EMI (electromagnetic interference). "

 

[Swerd]

I'm not an EE, but I had a few thoughts after reading the EE Times link.

• This was published in 2007. If this was an important finding, why haven’t we heard about this since then?
  
  
• References 1, 2, and 5 are the previous work of the authors Newell and Holland. References 3 and 4 are the work of Eugene Czerwinski. But Newell and Holland seem to be repeating in 2007 what they previously said, without taking the initial observation any further.
  
  
• References 2-5 seem to be published as proceedings of a meeting or conference. These are abstracts or a brief talk (roughly 20 minutes). Typically these are not peer reviewed, in contrast to full scientific papers.
  
  
• Let’s be generous and assume all these lab test bench measurements are good and could be reproduced by others. I don’t know if others have tried this or not. The authors said nothing about this.
  
  
• The authors say very little about audibility. Their lab test bench measurements will be significant if and only if they can also show that listeners could reliably hear the differences they measured at the lab bench. No scientific listening tests of any kind were reported.
  
  
• Finally, let’s talk about EMI or RFI that may have contributed to their observations. Look at two quotes from the article:

As had been seen the year before, a considerable amount of hash was being received from the air, including a 13 kHz signal which seemed to disappear around 9 pm each evening, even though nothing in the office or workshop was switched off at that time.

The studio in question was sited close to emergency service aerials (fire and police) yet nobody had commented about similar problems in similar monitor systems in other locations. The original complaints of an unusual slight harshness in the sound only applied to the high sensitivity loudspeakers, and not to any other loudspeakers in the studio. The change to the RG59 solved the problem.

And here is a quote of their only valid conclusions:

As the evidence presented in this chapter has shown, loudspeaker cables seem to be sensitive to the equipment to which they are connected, and vice versa. What is more, the entire systems seem to be sensitive to their environment, at least in electromagnetic terms.

Considering the interference they mention, it is hardly surprising that shielded speaker cables could make a measurable difference. This is nothing to get excited about.