Voice coil heating and the performance of passive XO, plus my funny experience at HTG

[Hartono]

"After the measurement, the results are smoothed out with a 5- seconds moving average. It would be interesting to see the result before this smoothing"

I've also raised this issue not long ago, but some people say that the measurement itself is not so accurate, with some artifact at the start and the end. being not an expert and not knowing the actual measurement setup I always try to keep open to suggestions.


Hartono

 

[rythmikaudio]

I am wondering how the author would quantify the impact of DC component generated by harmonic distortions. Assuming the system has only second order harmonic distortion, so it is polynomial is written as f(x) = x +k*x^2. But the x^2, when plug in the sin wave, will generate a DC component (or sinx*sinx = 1/2-1/2cos(2x), is this correct?). In general, all even order distortion generate DC components.

I'd like to clarify the harmonic distortion I referred to is not the distortion on the voltage, instead, it is the distortion on the current. Even with an ideal voltage drive, the voltage on the speaker terminals can be distortion-free, but the current will not be distortion free (that is one of the motivation and justification for speaker bi-wire, that is, keep the distortion current from interfering each other). The paper from Mills recommended using current drive, which the current is distortion free, but the voltage is not distortion-free. As one can see, if there is a DC current distortion component, it will take that from the current source in the measurement device to maintain 0 DC voltage, and the remainder current will then flow through the voice coil resistance can manifest itself as a DC offset related to the voice coil resistance.