Loudspeaker measurement using SMAART live ?

[Empee]

Hi there !

It's been a while since I've been here but I have a question
(and I have searched )

Is there anyone using SMAART Live as to measure T/S parameters of loose drivers ?

I'm trying to get it to work but none of my speakers tested so far
match the manufacturer's data.

I'm using the differential set-up as explained here

The soundcard is Sound Devices' USBPre


What I do is make a free air impedance plot,
then do a second plot with 30 gramms added to the cone,
read the data from my screen and plug it into this online calculator.


Does anybody use this method or do you have any comments on a better set-up or a different / more accurate calculation method ?


Kind regards from the Netherlands,

Empee

[ergo]

Try http://www.libinst.com/praxis_downloads.htm

Praxis allows measuring impedances and calculates T/S by curve fitting method and does that also in demo mode without buying the Audpod...

Ergo

[tthorsten]

try SAT LIVE by Thomas Neumann

www.take-sat.de

navigate to the english part and the endglish forum

[wintermute]

Hi Empee. I haven't used the software you mention, but I'll make a few comments

You say that the tested speakers don't match the manufacturers data. How close a match are you expecting? You should be very surprised if they do match! There are always tolerances.

Also breakin will affect what you measure (fs should drop after breakin) but in general even though all the parameters change, the overall effect is that the (modeling) results will be the same (as all the parameters change relatively). Have you performed a breakin?

What drive levels are you using when performing the testing. Dickason recommends using the lowest drive level practical. preferably (from memory, it's been a while) you shouldn't be able to hear any sound from the speaker when you are doing the test. If you can here the MLS pulse you are probably driving it too hard. Ideally you want the level low enough that it doesn't over excite the driver, but high enough that the signal is far enough above the noise level, that you get valid data that isn't coloured by noise.

Thirdly how are you mounting the driver when performing the test? It should be firmly clamped so that it can't vibrate, in a vertical position (assuming that is how it will be mounted in the speaker) preferably with as little around it (ie in free air) as possible. It is surprising the differences in measurements that can result from adequate/inadeaquate clamping of the driver.

Anyway although I haven't answered your question, hopefully the questions I have asked may be of value.

Tony.