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Old 25th January 2009, 10:29 PM   #1
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Default Best solution to missing B200 bottom end

Well I finally sprung for some premium drivers after tinkering for 18 years and picked up some lightly used Visaton B200's. These drivers are pretty good, the upper extension is really amazing considering the cone size but there is no getting around that 6db drop in efficiency from ~ 600hz down. I know some guys are running these without addressing the problem but I noticed it as soon as I fired them up, I even though there was something wrong with my recently modded CD player. I have them mounted in OB's much like the Omega's and was thinking about adding a second 8" driver set up to drop off at 6db per octave as the B200 begins to pick up steam at 6db per octave around 6oohz. Has anybody tried this yet? It seems a .5 helper woofer rated for about 93db of efficiency should do the trick. I am currently using a sub to take over from about 100hz down.
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Old 26th January 2009, 08:26 AM   #2
Piek is offline Piek  Europe
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Hi,

you could use either the recommended filter for this drop or maybe add 2 visaton BG20.

http://www.visaton.de/bilder/weichen/gross/solo20_w.gif

(Will still require a Sub)

-Micha
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Old 26th January 2009, 10:52 AM   #3
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I'm trying to stay away from filters even the line level ones. I hate the idea of throwing the B200's great efficiency away. The BG20 isn't a bad idea,I was thinking of finding an 8" driver with similar characteristics (except the price!) to the B200 as a helper. Also a second woofer would help limit the excursion the B200 sees. I think the hardest part is going t be rolling the .5 driver off smoothly with minimum phase shift then killing its output once it gets to about 1200 hz.
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Old 26th January 2009, 11:14 AM   #4
Piek is offline Piek  Europe
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What is the size of your Baffle and position of your B200?

-Micha
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Old 26th January 2009, 12:06 PM   #5
Piek is offline Piek  Europe
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Oh, well i thought about it again..

first: Without filter the B200 is not listenable to me (Had him in 3 enclosures, including open baffle)

second: if you still dont want any filters, you could use one Bg20 reverse on baffle so the filtering is mechanical by magnet etc, if looks arent that important. Benefit will be some more highs at the back of the baffle. Even then you gain just 3dB where you want more, since the difference from 600 to 10.000Hz is about more than 10db (!)

third: Just listen more off axis, the response will probably even out (to some extent) on 15 degrees or more.

-Micha
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Old 26th January 2009, 12:58 PM   #6
tinitus is offline tinitus  Europe
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Quote:
Originally posted by Piek
Oh, well i thought about it again..

you could use one Bg20 reverse on baffle so the filtering is mechanical by magnet

Wont work like that
Only significant difference will be lots of diffractions

If this Bg20 is that good, you could use a pair in paralel

Filter you need anyway

Though you could experiment with such pair of Bg20, mounted in a "ripole-like" arrangement...heavily stuffed = acoustic filter

Back of Bg20 could be either "boxed" or "ripole-style"
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File Type: jpg ob bg.jpg (16.7 KB, 607 views)
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Old 26th January 2009, 01:55 PM   #7
tinitus is offline tinitus  Europe
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Be aware that with no filter you get low impedance but just a small inductor will do, I guess

Slightly different
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File Type: jpg ob bg.jpg (18.4 KB, 561 views)
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Old 26th January 2009, 03:52 PM   #8
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Assuming you've got space on the baffle, stick an Alpha 15 on the bottom end & roll it off 1st order. If you're in a smallish room, that should be sufficient. If not, you'll need a couple of Alpha's per channel.
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Old 26th January 2009, 06:42 PM   #9
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Quote:
Originally posted by Piek
first: Without filter the B200 is not listenable to me (Had him in 3 enclosures, including open baffle)
Omce i got phase pugs in B200 i had no real issues with them (1.2 x 1.1 m OB, pic attached currently sans B200). Before that they were either hot (on axis) or you were wondering what tweeter (off axis).

The efficiency of these is not as high as the number would indicate.

dave

PS: when we had these on a 16' wide baffle (ie plywood used to fill in between and to extend the baffles attached), bass was quite extended. With a Q of 0.7 it is a case of the bigger the baffle the better.
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Old 26th January 2009, 07:23 PM   #10
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Quote:
Originally posted by planet10


PS: when we had these on a 16' wide baffle (ie plywood used to fill in between and to extend the baffles attached), bass was quite extended. With a Q of 0.7 it is a case of the bigger the baffle the better.

Dave, I would like to see attachement, I dont see.

16' wide baffles? Do you listen in a air craft hanger?
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