Thinking about building my first OB seakers, help me decide on the design

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I'm learning a lot about the OB design so please help me out. I'm trying to decide between a 2 way and a 3 way design but can't figure out which way to go. 2 way design with a full range driver and a tweeter on top vs a 3 way design with a big woofer on the bottom, mid range and a tweeter. Right now I'm leaning toward a 3 way design maybe with a U shape for the woofer to extend the low end and open mid and high drivers. What would be the advantage of a 2 way design other than a simpler crossover? And if you do 2 way how do you extend the base without also boxing in the mids?

I'm sorry if I'm asking basic/stupid questions, just trying to learn.

Early B.

With OB, you need plenty of bass. That means you're probably gonna build a 3-way with 15" woofers. Build a 2-way if you already have a subwoofer.   

Scott Joplin

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Hello Loty. Have you looked at the Linkwitz Lab site? I reckon it's the best place to start if you want to learn about OB and dipole speakers.


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  • To whom more was given more will be required.
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My suggestion for a hi-end music system is a OB FullRange driver as LiiAudio F15 or F18 if you want more bass. The best baffle shape so far is the Barrel shape as used by Decware.
Lii Audio F15 FR driver $399/pair, not each.
Here Decware OB with the Lii Audio F15 driver:

If one have a woodworker is possible try the Lii Audio F15($399/Pair, pair not each) 97dB/8Ω and benign impedance curve suited to OB or Bass Reflex box or the F18($540/pair), no Crossover, no Tweeter beaming, no Phase rotation, no driver sensitivity loss, no Harmonics loss, no Retail price.

But if you want less musical fidelity, less soundstage, less musical presence and less harmonics you could use a Two-Way OB with an unfamous cross-over(more  additional parts cost) as this image below:
This is a inexpensive DIY project from an AC member, it have only four(4) parts: Eminence Alpha15A + 4.7mH + Visaton B200 and a MDF baffle.


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If you do get the Lii drivers, I suggest  building test baffles before jumping into a more expensive finished baffle. I have the Lii Fast 15s (Xizi versions), found that a certain driver height and room positioning was preferred. In other words, a baffle on the floor didn't work well in my room (which of course effected the bass). Also play with toe-in, and don't be afraid to add some EQ (how ever done). I'm running mine full range now, later I plan on trying the Liis as mid-bass units in a three way active setup. Do lots of research before jumping in, here and also on the diyaudio "full range" and "multi-way" sites. One last thing, the Lii drivers were pretty hyped up for a while there, but there are a lot of OB driver fish in the ocean. :wink:

Scott Joplin

  • Jr. Member
  • Posts: 55
Do lots of research before jumping in
That's good advice, I'd also suggest if you haven't heard OB speakers in your room before, that you mock-up something cheap and simple (I used coaxial car speakers and sheets of cardboard) to see if you like the sound and you can place them far enough away from your walls.

Jon L

This "ABX open baffle" speaker may be a good option.  Coax driver on top with slot-loaded woofer, and parts list and source all already laid out for the DIY'er.

Jon L

Just saw this great video and sound demo for a variation of ABX open baffle plus dual GR Research Triple Threat OB subs.  Is this one of the AC guys?
Veeerrry nice, the type of sound I personally prefer, lively, detailed, and dynamic.