Hello. I have a question about modeling the acoustic design for a low-frequency speaker. I am confused by the different final frequency response with and without the "show effect of inductance" function. Which of these options will be closer to the real response?
Blue line with inductance effect. 2 dB differecnce at 55 Hz 😕
Blue line with inductance effect. 2 dB differecnce at 55 Hz 😕
A driver with only 4.5mm excursion does not likely have much additional inductance over what it's TS parameters indicate.
That said, TS ratings of Le may be done at 1kHz, and are not indicative of the Le at lower frequencies.
A high excursion driver like the one above your selection would more likely have higher Le and the upper rolloff associated with large/long voice coils.
Hornresp has a "Lossy Le" or semi-inductance model previously known as "large voice coil" option.
This thread may give you the background to understand the "show effect of inductance" function:
That said, TS ratings of Le may be done at 1kHz, and are not indicative of the Le at lower frequencies.
A high excursion driver like the one above your selection would more likely have higher Le and the upper rolloff associated with large/long voice coils.
Hornresp has a "Lossy Le" or semi-inductance model previously known as "large voice coil" option.
This thread may give you the background to understand the "show effect of inductance" function:
The result of activating the 'Show inductance effect' option seems to be quite unusual. At low frequencies, the effect of inductance on the response will generally be commensurately small, even when more sophisticated inductance modelling is used. The blue curve is really odd, in that it shows an unexpectedly high amount of response change at low frequencies. That seems to be a result of using the Z1k and Z10k parameters, rather than a simple inductance model based on a single Le value.
Where did you get those Z1k and Z10k values from?
For comparison, my result is shown below, for the low value of Le=0.19mH that this driver's Thiele–Small parameters specify in the datasheet. This approach to modelling low-frequency response has stood the test of time, and indicates that, for this driver, Le is but a relatively small effect (as expected).
From the speaker impedance graph. This behavior of the graph is not unique to this speaker, I also tried on others, including using the extended 4-parameter impedance model
https://noema.ru/wp-content/uploads/2024/07/48-4.pdf
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The measured impedance curve indicates that the driver in question has a very low inductance. Whichever way it's modelled, this small inductance should only have a small effect on the sound pressure and the impedance responses. Clearly, the modelled effects of including Z1k and Z10k are really large, and I don't know why that would be the case.