Measuring speaker stuff starting with Thiele-Small parameters

[DualTriode]

Repeat until the full power driver/enclosure measures and sounds correct.

Hello All,

Back again to visit and add a few things.

This time I have been checking out other thoughts about driver impedance measurement. It seems that things are less well connected to a simple set of driver parameters that can be plugged into speaker simulation software. It is more complex than that. There is a range of things between small signals and full on watts to drive a sub-woofer. It appears to include a fair amount of wishing and hoping if you intend to measure speaker parameters with small signal input and expect to forecast speaker driver performance in a fabricated enclosure.

One example input voltage makes a significant difference to resonant frequency. Temperature and humidity also contribute to the measured/calculated results.

Then there are different models that differ from the standard Theile Small model. The Wright and LR-2 models produce results that are more accurate than the old school TS/P. Still not indicators of full power performance. I get the impression that the speaker manufactures select test voltages and conditions and then tweak the published “TS/P’s” to ensure that their drivers will perform in enclosures calculated by the standard speaker enclosure simulation software.

Depending on how serious you are; measuring TS/P is just a first step in matching a driver to a enclosure. I see it going like this; measure the driver, fabricate a enclosure, measure the driver/enclosure and repeat until the full power driver/enclosure measures and sounds correct.

Thanks DT

Food for thought.
https://www.klippel.de/fileadmin/kl...iterature/Papers/Voice_Coil_ Impedance_04.pdf

 

[planet10]

It is more complex than that

As i believe i said earlier, T/S parameters are scalars collapsed from the curves that represent the changing parameters under dynamic conditions (and with changes of volume control).

The changes often tend to balance one another, but i like to design a box for greater tolerance to these dynamic changes. I have almost always found the factory m=numbers a good start so the place where something like LMS collapes to scalars is most often — in my experience — a good compromise for real life use.

Subwoofers probably have the largest shifts, so some finese in their design really helps.

dave

 

[DualTriode]

Back to testing drivers, Mid-Bass drivers this time.

I am looking to make a pair of Mini-2-Ways this time.

There are a couple of mid-bass candidate drivers sitting here on the bench. This is for fun so we are open to other thoughts.

I have read a couple of places that amplifiers and crossovers perform better wit Zobels or compensation networks in parallel with the mid-bass driver. Perhaps even less distortion.

A couple of references below.
https://leachlegacy.ece.gatech.edu/papers/zobel/zobel.pdf

https://www.klippel.de/fileadmin/kl...iterature/Papers/Voice_Coil__Impedance_04.pdf

https://audioxpress.com/article/voice-coil-lab-notes-improved-zobel-network



I have a couple of test plots of Impedance Magnitude and impedance phase for each below.

I have resistors on order for the Zobels.