Inductance Thread

[just a guy]

I wonder if any of those FR tests took into consideration the resistance of the cabling, etc to the DUT?

R=Rs + Re
Qes' = (Rs + Re)*Qes/Re

If Rs goes up, so does Qes'

Best if the tests are done with the connection between the amp and speaker as short as possible, if you want to make the comparison between the HR sim and the measured results more accurate. Or, account for Rs in the HR model.

There's a "know how" page on the site that explains his procedures. He might mention this but I seriously doubt it, as you are talking about fractions of an ohm here.

Anyway, the "normal" drivers sim just like they measure, the big heavy coil ones don't so I don't think the fraction of an ohm added by wiring has much (if any) effect.

 

[just a guy]

Interestingly, as i know you know, when more power is applied & the voice coil heats up, Re increases. It continues to increase as even more power is applied. This eventually results in thermal compression, which begs the question, why doesn't the continual increase in Re auto compensate for the increase in Le

I don't get what you are saying. Power compression and this issue are totally separate issues, they can't compensate for each other because they present as the same thing, a loss in motor strength and an overdamped response. If anything these two effects add, not compensate for each other.

Also, without using for eg the AceBass method i mentioned before, how would we be able to increase Re in an actual High powered sub ? Forgetting about using Very high power resistors

I didn't comment on it the first time you mentioned it because I don't know what AceBass is.

You absolutely do not want to increase Re in a sub, I can think of VERY few cases where that would be useful. All you want to do is increase it in the SIM so the sim becomes more accurate.

By the way, i want to congratulate you on your initial discovery, & continued investigations into this 🙂

Thanks.

 

[just a guy]

Hi just a guy,

Reactance is measured in ohms.

The value of Kxm shown in the data sheet is given in Henries (which to be strictly correct should be either henries or henrys with a lower case h, but that's another story).

Kxm is therefore an inductance, not a reactance 🙂.

The reactance of inductance Kxm at frequency f is given by 2 * Pi * f * Kxm

Kind regards,

David

Ok.

Just to be clear I don't know a whole lot about these complex frequency dependent parameters, I haven't read Leach's paper (it took a month to get through the last one I attempted with all the crazy math) and I just took a quick glance at Kravchenko's picture.

I haven't invested any time into the complex parameters method because these parameters are not easy to get and my favorite simulators won't accept them anyway, so they are pretty useless to me, but at a glance it does seem that they work in a similar fashion as what I'm doing with my method. Of course my method is considerably less refined (especially at this early point) but it does seem to work very well, at least much better than ignoring the issue or other popular methods like adding artificial Le to the sim which doesn't work at all.

 

[Zero D]

@ just a guy

To be perfectly frank, until now it sounded as if you were looking into how to increae Re in a real sub, not just in a sim. Now i realise it's only in a sim. My bad ! That's why i mentioned "some" of those things, the others that are relevent are obviously ok.

For the record, AceBass was/is an ingenious way of altering several of the T/S parameters in Real Time on a powered sub invented & patented in the 1970's ! Sub Ace-Bass 3 | Audio Pro Threads on here too about it.

Powersoft now incorporate this into their software.

Processing and Control Specifications/Virtual Speaker Mode http://www.powersoft-audio.com/docman/922-powersoft-bac-ipalmod-system-introduction/file

Regards