# T/S parameters. Help!!!

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#### Higo

I´m a newbie in the Speakers world and I want to ask you a few questions.
The most important, I´m sorry for my written english. I know that I need to improve it.
Well, I live in Argentina and due to our economical situation, is imposible to import speakers from others countries (Vifa, Audax, etc)
Even a book like "The Loudspeaker Design Cookbook" it´s imposible to find it.
Anyway I bought a couple of speakers (8" woofer, 8 ohms, polypropylene cones,bell melting, Re=6.9) made it here.
Yesterday I was measuring the impedance. Afortunatly I didn´t have problems. But I´m a litle confused. I found fs at 48 Hz (Zmax=23.51 ohms). And I started to search f1 and f2.
According to www.speakermania.com/transd/find.html, f1 and f2 are the frecuencies where Z=R1 where R1=(Sqrt(Zmax/Re))*Re. With this I found R1=12.734 Ohms and f1=38 Hz and f2=59 Hz. Then fs=Sqrt(f1*f2)=47.32. Everything ok!!!
If I follow the ecuations that appears in the mentionated page I have:
Qms=4.218
Qes=1.753
Qts=1.238

????

Due to this values I decided to use other method that apears in www.sound.au.com/tsp.htm and:
Qms=3.51
Qes=1.02
Qts=0.79

The question: Which´s right??? What I´m doing wrong???
Any help will be appreciated.
Marcelo (Higo)
from Buenos Aires

#### daatkins

Higo,
If building speakers is something you intend to do some more of, I'd suggest that you download a copy of Speaker Workshop from...

http://www.audua.com

(it's free). It does automatic impedance measurements, TS pararameter estimation, acoustic measurements and much, much more. The software only really comes into it's own if you build a jig; see

http://www.gti.net/wallin

... for more details about the jig.

Hope this helps,
David