Here we are, December 3, and no details have "followed" about the December 5 zoom call. When has a vendor given less than 2 days notice of a presentation? That is just odd .....
*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
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Townshend is inviting you to a scheduled Zoom meeting. Time: Dec 5, 2020 18:00 GMT Topic: Townshend cable measurements Demo + Q&A. To demonstrate that characteristic impedance matters in the case of speaker cables. Forum questions regarding voltage and oscilloscope timebase settings will be addressed. The session will have the following format: A brief overview of the paper. Introduction of the test set-up. A live repeat of the experiment. An opportunity to discuss the theory and test practices. To facilitate preparedness, should you have any specific questions, please feel free to pre-submit them to us. This is not a requirement. Open section for ad hoc or any further questions concerning cable testing. Join Zoom Meeting https://zoom.us/j/93569703283?pwd=Q3hHOStzU0dENnArY0lGV2F3ZGJFZz09 Meeting ID: 935 6970 3283 Passcode: JYzH2K The session will be recorded. |
Please come prepared to discuss the following questions, as a start. 1) Why does your speaker electrical model does not match impedance curve shown. 2) Why are you using an electroacoustic speaker model that is not accurate for electrical transmission line effects. 3) Why are you not incorporating parasitic capacitance which is essential for proper transmission line modelling. 4) What are the scales on the oscilloscope plots. 5) Why do you use the wrong formula for impedance? The formula you use only works at high frequencies, not audio frequencies. 6) Why do you use an incorrect method of measuring characteristic impedance in yoru paper. 7) Why do you insist that a 10KHz square wave is "audio" frequencies, when only the fundamental 10KHz sine wave in that square wave is in the audible band. 8) Why are you passing off a simulation that is obviously not incorporating properly characteristic impedance as a simulation of characteristic impedance in a transmission line circumstance. 9) Why are you passing off a simulation as accurate that does not take into account the very significant change in characteristic impedance of cables at audio frequencies. 10) Why have you ignored skin effect. 11) You have shown no CAUSATION between characteristic impedance and cable voltage drop. You have only shown at best some correlation, but no causation. Why do you feel, given the lack of proven causation, that you can say definitively it is due to transmission line effects? 12) Given the posted impedance curve of your simulated load, why do the cable voltage drops NOT follow the impedance mismatching that must occur as the impedance of the load changes with frequency. Given your hypothesis, the voltage drop w.r.t. frequency MUST follow the cable impedance / load impedance graph. It does not. 13) You have completely ignored inductance as a causation. Why? 14) Why does your table of wires and their characteristic values does not correlate to the graph and confuses readers. 15) Why did you label a graph the frequency response of the cable when it is clearly not. It is the cable voltage drop versus frequency which is not the same thing. This is deceptive to an uneducated reader. 16) Why is there a 2db measurement drop at high frequencies which without knowing why puts unbounded error on the measurements at high frequencies. 17) What is the scale of the spectrum graph is not listed, only db and this is a near meaningless term without the required scale. 18) What are the settings for the spectrum analyzer as they are not listed so we don’t know if it is average, RMS average, peak, etc |
Well Max showed, and continued to ignore 100+ years of settled engineering. He was joined by David from Wireworld who communicated his own brand of lack of engineering knowledge. Altogether it was as expected. Oh ... get this, the source impedance was not an amplifier with say close to 0, or at least 0.1 ohm, it was a 400 ohm source impedance. According to Max, that does not matter cause it acts as a current source. I feel sorry for those potential customers who will be mislead by someone who passes themselves off as knowledgeable, but clearly, on this topic, is not. |
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