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PostPosted: 30 Jan 2017, 08:54 
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Joined: 30 Jan 2017, 08:00
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Location: Israel
Hi all,
My name is Nimrod, from Israel, new here.
I had pair of Vifa ST05 shelf speaker laying around my basement. one day flood ruined the MDF enclosures but the water didn't reached to the drivers.
the other day i decided to make them new enclosures.
when opened up I found inside those components:
Vifa D25TG-55 tweeter with Philips capacitor 6.8uF 63V attached to positive leg in series.
Vifa C13WG-15-08 5'' woofer.
No crossover
both speakers were parallel connected the the input.
from what I understand Vifa components are from quality, hence I intend to rebuild this speakers in TRS-80 configuration(22L):https://sites.google.com/site/undefinition/diy-trs-80.
Is it possible? Is this configuration good in volume to this drivers?
Should I build a crossover for this drivers? if yes suggestions will be welcomed.
any suggestions/remarks are greatly welcomed, since my acoustics knowledge is little,
Best Regards,
Nimrod.


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PostPosted: 20 Feb 2017, 14:12 
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Joined: 05 Aug 2016, 14:35
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There is no reason why not. However, you may want to look into a more precise crossover as a simple capacitor is a very primitive expedient. Not to suggest that other quality makers were not equally as simple (Dynaco and early Advent, for example), but as you are messing with the size of the 'box' you may want to make sure that your crossover is apt to the task. They can also be had off the shelf, at not stupid prices, either.


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PostPosted: 28 Feb 2017, 10:17 
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These danish units Vifa C13WG-15-08 are in specs in between models Vifa C13WG-08-08 and Vifa C13WG-19-08, which you can find in the links below. Enclosures (closed) up to 10 L and enclosures (vented) up to 12 / 20 L, don't go larger. If you want to reuse a 22 L enclosure just add blocks of wood 2 - 6 L to reduce the volume. I know a Vifa C13WG-15-08 will work fine in a 16 - 20 L enclosure.

Note the lowpass crossover filter of these TRS-80 is designed for a Dayton unit and is not proper for the Vifa. A new calculation of crossover filter is needed and also the tuning of the vented port has to be changed for optimization ( even if the 2"x3" port in your enclosures actually would work )

http://www.sea.vg/vifa/C13WG-08-08.pdf

http://www.sea.vg/vifa/C13WG-19-08.pdf

http://nedlab.com/wp/wp-content/uploads ... weeter.pdf


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PostPosted: 28 Feb 2017, 17:29 
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Joined: 31 Dec 2008, 15:34
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Some modifications to the shown crossover filter can be done and it should be functional ( do you have the skills to manage changing the filter ? ). A new calculation of crossover filter is needed, i've got some ideas for a combined BSC + 2'nd order 12 db/oct filter for the lowpass and 2'nd order 12 db/oct filter for the highpass with 5-6 db damping.


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PostPosted: 02 Mar 2017, 05:52 
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Joined: 30 Jan 2017, 08:00
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Location: Israel
Thank you KrammeAcoustics, for the very helpful info.
I do have the soldering skill, but not the designing skills,
Will use your crossover suggestion.
lastly, how can I calculate the modifications needed for the venting port?


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PostPosted: 02 Mar 2017, 15:28 
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Nimrod216 wrote:
Thank you KrammeAcoustics, for the very helpful info.
I do have the soldering skill, but not the designing skills,
Will use your crossover suggestion.
lastly, how can I calculate the modifications needed for the venting port?


You're welcome


Last edited by KrammeAcoustics on 02 Mar 2017, 15:56, edited 1 time in total.

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PostPosted: 02 Mar 2017, 15:42 
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Nimrod216 wrote:
Thank you KrammeAcoustics, for the very helpful info.
I do have the soldering skill, but not the designing skills,
Will use your crossover suggestion.
lastly, how can I calculate the modifications needed for the venting port?


As i said you can use the port as it is, at least you should try it first as it is. I've tried to calculate it to a tuning of 52 hz and hits the width x lenght it is already 2" x 3". See the screendump below from the online calculator.

I'm using Linear Team's Win ISD and Win ISD Pro, you can download both in this link, or simply use the online calculator: http://www.linearteam.dk/default.aspx?p ... calculator


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