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Old 17th September 2005, 03:15 PM   #1
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Question DIY Thiele/Small measurements ??

Hello,

I have ordered some Supravox 165GMF drivers, am waiting for them, and already have the data about them (Supravox gives a personal T/S parameters sheet with each driver).

The problem is that the params are quite far from the published ones (http://www.supravox.fr/haut_parleurs/165_GMF.htm) :

Driver 1
Fr : 78,48
Vas : 27,4
Qms : 7,167
Qes : 0,488
Qts : 0,457
Re : 5,5
Sd : 165
Bl : 5,6543
Mms : 5,7500


I modelled the enclosure again and it definetely affects the tuning.

I suppose (I hope) that this difference is mainly explained by a lack of break-in :

So, I plan to measure the T/S after the drivers are broken in.

I did a lot of search on the forum & the web and found that I need several things :

- a microphone, which I have
- a soundcard, which I have
- a mass to add on the driver, which I don't have
- a sealed box which I can build
- a software which I don't have


So I ask you, experienced DIYers , what you suggest me concerning :

- the mass : I can get a 0.01g precision at school, but don't know which mass I should add. Any suggestion ?

- the software : I found sample champion and Praxis, both are not free and Praxis needs quite boring cables. Do you know a good freeware program that could do the same ?

- the box : should it rather be a sealed enclosure of a given size, or a kind of open baffle ?


Any suggestion welcome !
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Old 18th September 2005, 12:47 PM   #2
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As far as mass blue-tack (fun-tack, sticky-tack) works, and is easy to add and remove from the cone. I'm not sure about your question for the box, what are you measuring using the box? Not Vas I assume. If this is for accustical measurements, I would just get all your T/S parameters, model and build your box, then do accustical measurements in that. Or maybe the box is for getting the T/S parameters, in which case open baffle is fine. Really anything to hold the driver off of the ground is fine.
Joe
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Old 18th September 2005, 12:57 PM   #3
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WinISD can do this too.

There was another, but for the life of me, I can't remember the name
(somebody help me here - light grey GUI, almost looked "GTK-like")
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Old 18th September 2005, 05:14 PM   #4
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Thanks a lot guys !!

I'll get some very very precisely measured blutak to put on the speaker (hope I won't damage the dust cap ).

I will try WinISD for this when I have more time !
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Old 18th September 2005, 05:30 PM   #5
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I downloaded WinISD, and I found nothing to measure T/S params, in the old and new version. I looked at the help file but it seems that there's nothing like that. Am I wrong ??
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Old 18th September 2005, 11:38 PM   #6
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In the alpha version, it does a lot of calculating of the missing stuff. If you can find your "Q's" and Vas or Fs, it'll pretty much do the rest.
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Old 19th September 2005, 01:03 AM   #7
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To calculate Vas (& some other parameters) you require either added mass or a box of known volume small enuff to dramatically raise Fs.

I use FuzzMeasure (& an auxiliary spreadsheet) to calculate T/S parameters. Works a charm.

dave
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Old 19th September 2005, 03:41 AM   #8
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Quote:
Originally posted by planet10

I use FuzzMeasure (& an auxiliary spreadsheet) to calculate T/S parameters. Works a charm.

dave

spreadsheet is a good idea. I've just been using a calulator, kind of a pain.


Joe
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Old 19th September 2005, 03:51 AM   #9
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You can try Praxis from http://libinst.com/praxis_downloads.htm

Without hardware it works in freeware mode but has a full T/S parameter measurement / calculation regime available.

Ergo

PS. Oh yes - it makes a T/S parameter caclulation with curve fitting procedure, so it's much more precise than hand calculations.
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Old 19th September 2005, 06:29 AM   #10
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[QUOTE]Originally posted by ergo
Without hardware it works in freeware mode but has a full T/S parameter measurement / calculation regime available./QUOTE]

Have you actually gotten it to work. I've been talking to some people with the full-blown version and they are having (were having?) a hard time getting it to work.

FuzzMeasure is using a method based on the manual method, but curve-fitting is in the works.

dave
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