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Old 6th December 2002, 10:09 PM   #1
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Default help, need some figures

hi guys,
does anyone have/know a link to find the following numbers:

Linear Exercursion - Xmax & Exercursion - Vd

for:

Vifa M25WO-49-08

and if possible Vifa C17WG-69-08, Vifa D26NC-15-06

thanks in advance,

Alex
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Old 6th December 2002, 10:42 PM   #2
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http://www.d-s-t.com/vifa/index.htm

Should have everything you need.

Pete
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Old 6th December 2002, 10:47 PM   #3
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that's where i've got everything so far except for Xmax and Vd, vifa don't state the xmax or vd

unless they are codewords for something else?

Alex
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Old 6th December 2002, 10:48 PM   #4
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is Xmax Air Gap height?
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Old 6th December 2002, 11:15 PM   #5
Wizard of Kelts
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Hang on-got the figures right here. Take a moment to calculate.

Air Gap Height is part of the Xmax calculation. Will explain momentarily.
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Old 6th December 2002, 11:19 PM   #6
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thanks bud, so can you work it out with a formula from the stats provided from vifa?

if so the D26NC-15-06 datasheet can be found HERE as d-s-t only have the newer 55-06 version,

if you use a formula can you provide it so i can work out future xmax values,

thanks in advance,

Alex
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Old 6th December 2002, 11:36 PM   #7
Wizard of Kelts
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Join Date: Sep 2001
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First the formulas for Xmax and Vd

Xmax = maximum one way excursion-from center to extreme
Vd = Volume of air displaced, (moved), by the driver.

Sometimes Xmax is given as front-to-back linear travel, but it should be given as center-to-end.

Here are the formulas:
Attached Images
File Type: gif formaula for xmax and vd.gif (3.3 KB, 329 views)
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Old 6th December 2002, 11:51 PM   #8
Wizard of Kelts
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Join Date: Sep 2001
Location: Connecticut, The Nutmeg State
For the Vifa M25W0-49-08:

The Effective Diaphragm Area, (Sd), = 346 square cm.
The Voice Coil Height is 14 mm. The Air Gap Height is 6 mm. Therefore, the Linear Xmax is (+ or -) 4 mm.
Therefore, Vd = 346 sq. cm times .4 cm = 138.4 cc.

For the Vifa C17WG-69-08:

The Effective Diaphragm Area, (Sd), = 143 sq. cm.
The Voice Coil Height is 12 mm. The Air Gap Height is 6 mm.
Therefore, the Linear Xmax = (+ or -) 3 mm.
Therefore, Vd = 143 sq. cm times .3 cm = 42.9 sq. cm.

For the Vifa D26NC-55-06, (the new substitute for the 26-15)
Effective Diaphragm Area, (Sd) = 7 sq. cm.
The Air Gap is longer than the Voice Coil by .5 mm. I assume that means it can move linearly (+ or -) .25 mm. Don't hold me to that. It's a tweeter anyway-things are different.
Estimated Vd = 7 sq cm times .025 cm = .175 cc.

By the way, mechanical Xmax for woofers is usually 1.5 to 2 times the Linear Xmax.

Do you have the response charts for the C17 WG? If not, they are located here:
http://www.mass.com.au/masssales/pdf/C17WG-69-08.pdf

I'll recheck the figures and edit if necessary. If I am off on the calculations, as an American I can blame it all on Metric!!
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Old 6th December 2002, 11:54 PM   #9
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thanks,

now when the software calculates port sizes, when you chnage from 1 to 2 ports the length doubles plus a bit.

for e.g.

currently with one port 66mm diameter and 100.4mm long when i change to two ports @ 66mm diameter i get 249.1mm length.

now is the 249.1mm the total length for both ports or 2 ports @ 249.1mm length? being around 500mm total?


thanks,

Alex

yes i have the charts
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Old 7th December 2002, 12:01 AM   #10
Wizard of Kelts
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That would be 249 mm for each port tube. Each tube will be 66 mm times 249 mm.
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