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 !
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 !
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
Joe
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
I use FuzzMeasure (& an auxiliary spreadsheet) to calculate T/S parameters. Works a charm.
dave
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.
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.
Has anyone used the "Dayton Woofer Tester 2"? (It is not just for woofers, it can test any driver.)
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=390-802
At $160 it is not exactly cheap, but I would be willing to pay that price if it worked well.
/Dave
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=390-802
At $160 it is not exactly cheap, but I would be willing to pay that price if it worked well.
/Dave
I looked at Praxis again, it seems to have nice T/S measurements. It isn't an easy soft to use but has many possibilities.
I'll try to play arround with it when I have more time, and when I have a 0.01gr precision instrument in my hands
I went on Fuzzmeasure website but the download doesn't work.
Talking about this, what additional worksheet do you use with it ?
I'll try to play arround with it when I have more time, and when I have a 0.01gr precision instrument in my hands
I went on Fuzzmeasure website but the download doesn't work.
Talking about this, what additional worksheet do you use with it ?
Looking at the list of equipment that you do have, you might be interested in guide I have written. You don't need any added mass email me if you want me to send you the PDF and are prepared to offer some feedback on the processes. It is written with beginners in mind but assumes a (very) small amount of electronics knowledge.
email me if you want me to send you the PDF and are prepared to offer some feedback on the processes. It is written with beginners in mind but assumes a (very) small amount of electronics knowledge.
youyoung21147 said:
Chris will be interested that you failed to download it... can you try again and let me know, Note: that to use FuzzMeasure you have to be running OS X and given that you are trying out Praxis, my guess is that you aren;t.
I've attached the spreadsheet, which i downloaded & modified for my use from "Best ever TS parameter calc.xls" (i measure reams of drivers). Hopefully it is self-explanitory (only calculates using the added mass method)
dave
Dave,
thanks so much for sharing your worksheet. After reading your ealier post I thought about making my own spread sheet, unfortunatly inertia was against me . I had always done the calculations with a calculator, which was a real pain with all the conversions and what not. I always had to calculate it at least twice to make sure I had not messed anything up.
Thanks
Joe
thanks so much for sharing your worksheet. After reading your ealier post I thought about making my own spread sheet, unfortunatly inertia was against me
. I had always done the calculations with a calculator, which was a real pain with all the conversions and what not. I always had to calculate it at least twice to make sure I had not messed anything up.Thanks
Joe
planet10 said:
If you guys are interested, you can find more details of my curve fitting work here:
http://www.supermegaultragroovy.com/FuzzMeasure/perfect_fit.html
It's a pain to implement, but now that I have it working, it's only a matter of time before it hits the final product.
Cheers,
Chris
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