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Old 20th September 2009, 06:54 PM   #1
happyb is offline happyb  United States
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Default Wanting opinions on first OB build

I am wanting to build a first pair of OB speakers, but am not sure where to begin. I am looking for something that is relatively inexpensive and that would fill a large space around 30x30. I am thinking of a design with a 12" woofer and tweeter like the Manzinita project here, but am not sure if this would work with my large space. And secondly, iI was wondering if there are any other OB designs with cheaper drivers that I could get my feet wet so-to-speak with? Thanks.
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Old 20th September 2009, 09:21 PM   #2
MJK is offline MJK  United States
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You might try something like this :

http://www.quarter-wave.com/OBs/OB_Design.pdf

There is also software to do the design work for a two way passive OB system on my site.
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Old 20th September 2009, 10:05 PM   #3
tinitus is offline tinitus  Europe
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What do you consider "relatively inexpencive" ?

http://www.aespeakers.com/drivers.php?driver_id=28
Dont know if they are still available

Last edited by tinitus; 20th September 2009 at 10:10 PM.
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Old 20th September 2009, 11:56 PM   #4
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Betsy and Boomer?

http://www.wildburroaudio.com/speakers.php

http://www.zillaaudio.com/betsy-boomer.htm
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Old 21st September 2009, 12:26 AM   #5
tinitus is offline tinitus  Europe
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2.5way
2x 8" Goldwood http://www.parts-express.com/pe/show...number=290-355
2" tweter http://www.parts-express.com/pe/show...number=264-807
Total 120USD, +xo components

But in a large room, I dont know
Maybe in a HUGE baffle, with 4 woofers, WW.WTW
Total 200USD

Last edited by tinitus; 21st September 2009 at 12:33 AM.
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Old 21st September 2009, 04:26 AM   #6
happyb is offline happyb  United States
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Thanks for the replies. I really like the idea of a eminence alpha 15 and a full range, but I also like the price of the goldwood tangband. Any idea what kind of x-over would be involved for the goldwood/tangband speakers? Also what about something like this eminence coaxial? Would that possibly work by itself as a fullrange?

Last edited by happyb; 21st September 2009 at 04:32 AM.
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Old 21st September 2009, 08:05 AM   #7
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Hi Happy,

What are your design goals? With OBs there are tradeoffs.

Simple/passive: need big woofers and big baffle. Not so smooth or deep bass.

Complex/multi amp: Smallish woofers, small size, smooth and deep bass -> Orion or NAO

Extreme: something like this: http://www.mfk-projects.com/theatre_woofer.htm
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Old 21st September 2009, 08:17 AM   #8
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I agree with GainPhile . Especially where "sonorisation" is the goal , for best efficiency you have to consider the total power applied to the speakers and the resulting air pressure you'll get.For OB setting it's compulsory to have a 20-60 Hz bass boost...
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Old 21st September 2009, 12:21 PM   #9
tinitus is offline tinitus  Europe
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Quote:
Originally Posted by happyb View Post
I also like the price of the goldwood tangband. Any idea what kind of x-over would be involved for the goldwood/tangband speakers?
I have the 2" TB
Only made a very quick "xo"
At first it sounded awfully harsh
Then I added a rather big resistor in series, and things happened
Sounded quite sweet and airy
Better than any cheap fullrange driver
33-47uf in series, and a resistor
Its crossed quite low
Might be possible to mount a waveguide
The very low xo point is the trick with this 2"
Which is also theoretically perfect for WTW configuration

2.5way means that ALL 4 woofers plays the same bass, but the 2 bottom woofers only play bass/midbass
2.5way for OB ought to work quite well, dealing with some of the dipole rolloff below 500hz
With a very big baffle it will be lower
For the 2.5way you need a big inductor(5mH?) in series with 2 of the 4 woofer in a WW.WTW
I can easily draw you a good xo schematic
Only, I cant give you the exact component values as I dont have the Goldwood woofers
Attached Images
File Type: jpg 2.5.JPG (18.9 KB, 79 views)
File Type: jpg 2.5way OB.JPG (18.5 KB, 74 views)

Last edited by tinitus; 21st September 2009 at 12:44 PM.
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