*WHITE PAPER* The Sound of Music - How & Why the Speaker Cable Matters


G'DAY

I’ve spent a sizeable amount of the last year putting together this white paper: The Sound of Music and Error in Your Speaker Cables

Yes, I’ve done it for all the naysayers but mainly for all the cable advocates that know how you connect your separates determines the level of accuracy you can part from your system.

I’ve often theorized what is happening but now, here is some proof of what we are indeed hearing in speaker cables caused by the mismatch between the characteristic impedance of the speaker cable and the loudspeaker impedance.

I’ve included the circuit so you can build and test this out for yourselves.


Let the fun begin


Max Townshend 

Townshend Audio



F78318cb 1fc9 49a2 8d02 edd399ef66f5Ag insider logo xs@2xtownshend-audio
"Highly experienced electronic engineers" ....

It is not a matter of whether I disagree or not. Anyone with a basic knowledge of transmission lines, knows that the speed of reflection is so fast, that the signal quickly settles to the final value, and since we are looking at frequencies of <=20Khz and lengths of 7 meters, the error is literally smaller than 1000db.

Let’s talk about your "figure 3". As I stated previously, your scale is not defined (which another noted above), so it is hard to properly interpret comparative results, especially since in addition, you have a 2db roll-off at 20Hz, which we don’t know if it is causes by amplifier saturation, measurement roll-off, amplifier roll-off, etc.


Let’s talk about other errors. Your impedance shown in Figure 2, dummy load does not match the circuit. The 330uH inductor is 2*pi*f*l at 20KHz = 41.4 ohms. That is in series with the 7.3 resistor putting a lower limit on impedance of 48.7 ohms. The 1.4mh in the other leg is almost an open circuit at 20KHz. Yet you show 8 ohms impedance at 20KHz. Gee .... what could be wrong here? Could it be that your model is missing the Zobel that is typically on amplifiers for stability. Was that actually in your load or not? Hard to make claims when even the most basic aspects of your article are wrong.


Your appendix has a column Cable Fig. 2, but figure 2 is the dummy load, and the numbers in this column don’t actually relate either the traces Figure 3, or Figures 4-10 as there is no way to correlate them. The one marked XXXX appear to the same cable in 6, 7, and 8 meter lengths (point of that was), but in the Cable Fig. 2 column, it is marked 5, 4, and 6 which has no meaning to anything else. And then another marked XXXX that is 10 meters but is a different cable. I don’t know who you had peer review this, but you should fire them. I am up to at least 4 glaring errors without even getting to the conclusion.


So as I said again, Figure 3 is explain by inductance -- measured with a proper inductance meter close to the actual frequency, and as necessary, also taking into account skin resistance.


Of course, to properly correlate anything to Figure 3., you would need to fix the measurement errors, define what the scale actually is, define the readings on the spectrum analyzer (rms? voltage average, peak), and provide accurate inductance and capacitance values for specific cables as they relate to figure 3, something you have not done at all.

However, as I have stated in my previous posts, using educated guesses, variances of 4-5db in the cable drop method you have used would be what happens between the inductances listed for the several different types.



audio2design235 posts11-21-2020 2:58pm
"Highly experienced electronic engineers". Actual engineers do not call themselves "electronic" engineers. They call themselves electrical engineers, perhaps electrical and electronic engineers. Please feel free to share the names and education and work qualifications of those that peer reviewed it.
If you're going to request this information, then it's only fair that you provide the same.
I had actually taken that out shortly after I wrote that Cleeds as I wanted to save them embarrassment after I tried to simulate the results in figure 3 and found more and more critical and fundamental errors in the paper.  I know it was not fully reviewed by engineers with the qualifications to analyze it.

However, I have my Bachelor's (EE) from Cornell before working in the recording industry for a major equipment manufacturer, before I left to start my own company supplying custom tools and services for equipment calibration and maintenance to the industry, that I sold before going back and doing a Master's (EE) and starting my PhD at Berkeley. Never finished that because I ended up running a group developing professional audio equipment for the recording industry. They were happy with their niche, I wanted to grow, so I put together a team that worked on software plug-ins and hardware that we eventually sold to a competitor. Since then been dabbling with a number of companies across a range of tech.  In other words, yes, I actually do have a clue what I am talking about, but that is probably evident from me picking up easily things like incorrect speaker models, simulations that can't possibly match actual transmission line effects, quick estimation of cable losses, and all the other errors in the paper.
It correlates because spreading wires apart increases inductive reactance that is dominant factor here. The idea that 7m speaker cable is a transmission line for audio signals is insane, IMHO. For 20kHz signal you will need about 1000m long speaker cable (1/10 of the 20kHz wavelength) to even start becoming transmission line. In such case reflections would be inaudible because they are in MHz range (and because speakers are 1000m away).  Why not to use 20kHz sinewave for the test? It is the highest audio frequency component of interest in the cable.  Please show me reflections of 20kHz sinewave in 7m cable.  Any cable.
Oh, and your "White Paper" shows 0.94uH/meter for Isolda, but your website shows 0.002uH but does not show a length.

I looked further into the Isolda, pictures and the dimension estimates I made.  I expect that 6.6uH is quite wrong, but that 0.002uH is quite wrong too (for 2 meters).


Given the lack of consistent numbers for Isolda, could be a function of the cheap meter, or measurement error, let's use the Isolda as a reference, use some of the inductance numbers in the chart, and the shown (but wrong) speaker simulator, using inductance only.

                    My Calcs    Value on  Graph
ISOLDA       2.6              2.6         (Used as ref)
                   8.5758         8.8
                   15.210        13.8
                   24.69          24.4

That's close enough to me, to show that inductance alone completely explains Chart 3, certainly within the framework of the obvious measurement errors.

Here is what you have done:
1) Showed a graph with expected change in frequency
2) Showed that order of magnitude characteristic impedance had a rough correlation to the measured results.

What you did not do:
a) Investigate other related effects ... like INDUCTANCE.b) Show a direct correlation via a measurement of impedance and measured error
c) Show a mathematical correlation between impedance and measured error.

See, I just did #3 above, and showed a very close correlation between inductance and the measured results.  That's science.

You also left out many necessary details so that your experiment could be corroborated.
And ...perhaps most of all, you did not relate your result to what the actual change in frequency response is.
On the very worst cable it is 0.4db at 20KHz.