Potential reason why people may dislike BR based solutions - diyAudio
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Old 1st January 2014, 07:47 PM   #1
Lojzek is online now Lojzek  Croatia
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Default Potential reason why people may dislike BR based solutions

Once I got my hands on famous Visaton AL 170 and needed to
work out what kind of box and what inner volume should a friend
of mine build to achieve good results basswise.

Altough manufacturer provides all relevant data, I still prefer to do it
myself because you never know what production changes may have
been introduced.

There is a saying that picture speaks 1000 words , so there you have
them attached.

If one ever feels the need to build just by relying on data published, in
case of Visaton at least, better think twice. Nothing dramatic but it could
make one think there is something wrong with BR principle, because
factory data are ideal so to say and yet it turned out in my case not to
be so. For the ones wanting to do their own graphs, txt files provided.

Wish you all the best in New Year !
Attached Images
File Type: jpg Visaton AL 170.jpg (99.1 KB, 409 views)
File Type: jpg Visaton AL 170 free air IMP.jpg (238.9 KB, 412 views)
File Type: jpg Visaton AL 170 added weight 7,8 g IMP.jpg (234.1 KB, 406 views)
Attached Files
File Type: txt AL170- air.txt (3.7 KB, 10 views)
File Type: txt AL170- 7,8g weight.txt (3.7 KB, 3 views)
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Old 1st January 2014, 07:59 PM   #2
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Location: Mar del Plata, a BIG seasonal getaway city, can see the Ocean from our residence.
What specific object or objects did you use for the "added mass" calculations?
Myself, I used American Nickels...as the American nickel is certified as weighing exactly Five Grams.
Measuring T/S parameters can be tricky........Have three individuals measure one specific driver for their T/S parameters & you will get three different set of values.


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Old 1st January 2014, 08:48 PM   #3
Lojzek is online now Lojzek  Croatia
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I used rubber cubes and had them weighed in jewelry store.
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Old 1st January 2014, 09:41 PM   #4
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It is only one parameter the differs: Cms. I don't think that there is a problem with your measurement setup, but maybe with your driver. Did you break the driver in? Or was it too cold? Possible Visaton used a wrong surround or spider. Ask them directly.
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Old 2nd January 2014, 01:49 AM   #5
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T-S parameters are not fixed values. The numbers you get actually depend on the method used to get them. I would EXPECT different measurements to give different numbers.

Having said that, the numbers should not be wildly different. An Fs supposed to be 38 should not become 66! That is simply a defect-probably assembled with the wrong spider as Baseballbat hypothesizes. Since that is a free air measurement, your added mass doesn't matter. Return the drivers. Qtc=0.7 will only ever make a horribly boomy vented box.
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Old 2nd January 2014, 08:02 AM   #6
Lojzek is online now Lojzek  Croatia
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Baseball: Both of the drivers were broken in because I got
them second hand and the former owner had them for couple
of years. So I guess that qualifies for breaking in. Inspection
was made at normal room temperature. It was definitely the
suspension.


head: It is a little late for returnig the drivers. I got rid of
them already. Bought them for cheap, resold them the same way.

Am a fan of Visaton and used to work with:

W250S-8; W250-8; W200S-8; AL 200; AL 170; W170S-8;
WS 17E-4; W130S-8; FRS 8; G25FFL, G20FFL; MHT 12

I guess that was on account having the store in my neighborhood.
I have always appretiated and admired german engineering ability
and skills. Would not hesitate to buy again if in need.
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Old 3rd January 2014, 04:00 PM   #7
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Sounds strange. Maybe they were wrongly stored by the former owner and they are sagged?
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Old 12th January 2014, 07:30 PM   #8
Lojzek is online now Lojzek  Croatia
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Sorry for the delayed reply, haven't noticed your question.
When I went to pick them up at seller's house, these drivers
were installed in a box with G25's and seemed to be in daily
use in his living room. No sagging or any similar issue was
evident.
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Old 12th January 2014, 08:04 PM   #9
tinitus is offline tinitus  Europe
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don't know, but using BR for a midrange driver does seem rather pointless

maybe they have got wrong and stiffer spiders later on, and not noticed it ... weird
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Old 12th January 2014, 08:07 PM   #10
Lojzek is online now Lojzek  Croatia
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I agree 100 % with you tinitus, only I'm pretty sure AL 170
is more than just a midrange.
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