JBL Apollo-like...?

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Hello, I`m a noobie in hifi-speaker building, only have meade couple of DIY-kits so far.
Then I started a new project, open baffles with Alpha 15a and Visaton BG-20.
For some reason or another, I could not get them to sound good to my ears, maybe it´s the Visaton witch should be better.

So I thought that why not try something different, and there´s my question:

Is there any known diy-designs that could be made to about same measurements as JBL Apollo, using Alpha 15 and BG-20?
I like it´s design a lot, kind of space saving, allthough with big element in it.

I have very limited budget, so maybe I could stretch to change BG-20 to B-200, or something else in that price limit, or get separate midtone and tweeter, allthough to get them so cheap could be challenging.
I am not looking top of the class, as you can see, more like decent one.
Main thing is to make them myself, but as good as possible.
 

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Ok,thanks.

So maybe I try to design it myself...
The maximum vented enclosure volume for alpha 15 is 177 liters.
If I make a enclosure 600x700x500mm, it´s 168 liters, and inside that box, top side, another 150mm high closed enclosure for bg-20.
It makes 45 liters, close to 47 optimum 47 liters for bg-20, and leaves 123 liters for alpha.
Then I calculate the lenght of the reflex tube for alpha, an then calculate crossover.

So, is this plan totally lunatic?
Can it be so simple?
Why loudspeakers usually are high and narrow, not low and wide?

Can I add tweeter in the same enclosure with bg-20, if needed?
 
Well, all this started when I bought cheap second-hand speakers for my computer, and noticed that woofers were totally broken. Then I bought cheapest 8" speakers that I found that weren't totally crap to replace them. Bg-20's.
The result wasn't very satisfying, and I started to look the net for better choice; diy-kit or drawings built around bg-20. It soon became clear that ng-20:s weren't the best choice for hifi-sector, but I thought that if I find a good design, I can build it with these and later, when I'll have the funds, chance them to something better.
Then I found open baffle speakers and instantly I was delighted of their simplicity and elegance. I learned that bass was the "weak point" of them, but anyway decided to give them a go, and Alpha 15a seemed to be best choice for woofer.
So, I made a baffle, 100 cm high and 65 cm wide, woofer is 28 cm and bg20 70 cm from the floor. And bass output was a disappointment. 🙁 in the corner of the room it was better but somehow "muddy".
And that's how I got here, dreaming about deep, beefy bass from my alphas... 🙂

I did read those links, and understand that I have to stick with open baffle with alpha.

Also I learned that H-frame is one way to improve bass output of open baffle: A comparison of OB, H-, M- and U-frame dipole

Usually H-frame woofer is on the floor, and full-scale and tweeter on top of it.
But why not place them beside of the woofer?
Or maybe make sealed or vented enclosure for full scale-element, and put it beside the woofer?
 
Visaton BG20 has a good bass. Put one in a reflex 100-130L tuned to 25Hz.
If you want a 10"/12" woofer to work with the Visaton driver, they need to be 94/95dB (for 4Pi BSC not taking into account the the Schroeder Frequency) and they aren't going to be in the cheap, besides you count them by the fingers of your hand.
12" AUDAX HT300G0 link
12" Audax HT 300 Z4 pdf you can try Audax HT300M0 Audax HT300M0 Professional woofer or Audax HT300M2 link

You can use the 92dB 10" SEAS CA26RE4X - H1316 (in a 55L reflex) if you attenuate a little the Visaton, it's all a matter of design. If you want high sensitivity (and LF extension) use 2 low frequency drivers.
10" H1316-08 CA26RE4X - SEAS pdf link
If you want to use 2 woofer drivers with lower sensitivity (91dB) look at the 10" H1305-08 CA26RFX - Seas pdf link
They work great in a 70L reflex. You can use one of this drivers above to test but if using lower sensitivity then attenuate your main driver or use 2 woofers in parallel.
 
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