Topic: T/S Parameters

[rustyns]

Given a driver for which the manufacturer does not supply the T/S parameters, how can I "find out" what the parameters are?  Usually, only the nominal and peak power ratings, the impedance and the diameter are known. What tools and techniques are needed to measure or compute the parameters? And can they be done without anything too sophisticated or expensive?

[rustyns]

Hmmm...

I searched harder and found this  --->link to Rod Elliot's site<---

Has anyone tried this out?

[wraith]

just curious, what will you be using the TS parameters for, crossover design, or a woofer enclosure?

If its a woofer enclosure, you can get away without knowing the paramaters by estimating the woofer's resonant frequency, then building a transmissionline-based enclosure.  You can estimate the woofer's resonant frequency by using an SPL meter + frequency sweeps, or via a realtime analyszer rig + pink noise.  The lower frequency at which the amplitude starts to decrease dramatically is the resonant frequency.

If its for crossover design, you would really need the parameters.

[rustyns]

both sana. pero i was hoping na hindi kakailanganin ng masyadong expensive na equipment.

just curious, what will you be using the TS parameters for, crossover design, or a woofer enclosure?

If its a woofer enclosure, you can get away without knowing the paramaters by estimating the woofer's resonant frequency, then building a transmissionline-based enclosure.  You can estimate the woofer's resonant frequency by using an SPL meter + frequency sweeps, or via a realtime analyszer rig + pink noise.  The lower frequency at which the amplitude starts to decrease dramatically is the resonant frequency.

If its for crossover design, you would really need the parameters.

[wraith]

Here is a website with an alternative way of discovering T/S parameters: http://www.purebits.com/appnote16.html

you will need:
1. a full duplex sound card (one that has inputs and outputs)
2. their software
3. 2 resistors for calibration

in logic, it is similar as Rod Elliot's method.  only this time, computations are software-assisted.  this method is actually inexpensive if you already have a  good sound card and a copy of their software.

But the story does not end here... so far, this method and Rob Elliot's method only measures  TS parameters.  Dumax parameters (xmax, etc) are also important if you want to take woofer box design seriously.  For Dumax paramaters, only a Dumax device can measure them.