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What's the secret behind "slim" open baffles from JAMO and SPATIAL AUDIO??

Naveenbnc

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#1
Hi all....

When it comes to diy OB design, generally i saw large baffles. But how did Jamo and SpatialAudio manage to design very slim OBs??

One of the main functions of a baffle is to separate air/sound waves from the front and rear of the driver.

How did these companies manage to do it with very slim baffles ??
Any suggestions please...

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blackscorpio

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#2
Naveen,
this is something I also wanted to know.

I think I am going to hold off on the Ahuja FRD OB for now. I am thinking of doing an OB with 8inch or smaller FRD in a very slim baffle, with a expectation of 80hz to all the way from FRD & low end is supported by the existing Rythmik sub, below 80.

Hope this arrangement works out.
 
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#3
You don't need large baffles for OB always, that's mainly for applications where sub assist is not there. I had simulated 8" HiQ using Basta for a baffle size 10×20", got almost linear graph. I have made the baffles in solid wood but yet to assemble.
 

Naveenbnc

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#4
You don't need large baffles for OB always, that's mainly for applications where sub assist is not there. I had simulated 8" HiQ using Basta for a baffle size 10×20", got almost linear graph. I have made the baffles in solid wood but yet to assemble.
Wow....that's a relief to know we can do slim baffles :D
So they are 10" wide and 20" tall i guess ???
 
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#5
The Jamos are ~19" in width, not that slim. It has twin 15"woofers, probably high excursion drivers.
One can try replicating the design with other good drivers and is not that complicated if one goes active or better still use minidsp for each side (speaker).
There is no getting away from the excursion hungry nature of the OB/dipole, It almost always is the bottleneck.

If one is looking for a visually slim baffle then one can do it aesthetically, baffle can be made in clear acrylic/glass, it will be visually appealing and still keep it functionally big to avoid the low efficiency of slim baffle.

Two 15" drivers have about 1500cm2 area, that can be achieved with multiple smaller drivers. One can also go for push pull woofer array for the lows, it can meet the Sd (surface area) requirement and further reduce the baffle. There are many possibilities.
 
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#6
You don't need large baffles for OB always, that's mainly for applications where sub assist is not there. I had simulated 8" HiQ using Basta for a baffle size 10×20", got almost linear graph. I have made the baffles in solid wood but yet to assemble.
Whats the excursion needed for achieving 90db SPL at 3 meters listening distance for that driver at the lowest frequency of its use?
 

yogibear

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#9
Secret is simple. Remove the second bass driver and the slim baffle setup will collapse.

Further such designs also rely heavy on equalizing. Passive XO is another secret.

Third, they involve large woofers, mostly 15”. Try replicating it with smaller drivers, even if more in number, you will have no low end.

I do like the FRD W W design and will incorporate soon, with less wider baffles.
 

Naveenbnc

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#10
The Jamos are ~19" in width, not that slim. It has twin 15"woofers, probably high excursion drivers.
One can try replicating the design with other good drivers and is not that complicated if one goes active or better still use minidsp for each side (speaker).
There is no getting away from the excursion hungry nature of the OB/dipole, It almost always is the bottleneck.

If one is looking for a visually slim baffle then one can do it aesthetically, baffle can be made in clear acrylic/glass, it will be visually appealing and still keep it functionally big to avoid the low efficiency of slim baffle.

Two 15" drivers have about 1500cm2 area, that can be achieved with multiple smaller drivers. One can also go for push pull woofer array for the lows, it can meet the Sd (surface area) requirement and further reduce the baffle. There are many possibilities.
When I say Slim....I meant thickness of the baffle at the left and right side of the driver is slim.

Driver is big, but the baffle thickness looks like only 2 or 3 inches thick on both sides. Earlier i saw OBs with very large baffles. Baffle width is atleast a feet or more on all sides of the driver.

So when I saw these Jamo and Spatial Audio, I started wondering how the managed slim baffles. Is there any different design approach, or may be some drivers are specifically suitable for slim baffles etc. etc.

But any way....thank you so much for the inputs....:)
 
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Naveenbnc

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#12
Secret is simple. Remove the second bass driver and the slim baffle setup will collapse.

Further such designs also rely heavy on equalizing. Passive XO is another secret.

Third, they involve large woofers, mostly 15”. Try replicating it with smaller drivers, even if more in number, you will have no low end.

I do like the FRD W W design and will incorporate soon, with less wider baffles.
I didn't understand the inner science ....but please correct me if I'm wrong with the below points.

1. Using 2 bass drivers allows us to design a slim baffle. But only 1 driver may need a bigger baffle.

2. If we don't bother about low end extension, (use smaller drivers may be 8") will we atleast get good midrange and highs with slim baffle ???
 

Naveenbnc

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#13
The reason I'm asking is.....these OBs are looking super cool, and easy to make.

I have two 10" bass drivers. If I get good enough "mid range and highs" with "slim" OBs by using 8" or smaller FR drivers,

I am any way building two ported subs with these 10" bass drivers, I can just add those slim OBs on top of these subs, and cross them around 100hz something.
 

yogibear

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#14
3 way OBs with sealed/ported subs have been done. You don’t need wide baffles for midrange and none for tweeter.

MTM OB with sealed / ported subs have been done. You already did a centre Chanel with not so wide baffle. What was your experience ?

Mine less wider baffle build stands at 24” from earlier 30” and I don’t like to equalize heavy.
 

Naveenbnc

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#15
I'm so damn happy with my center channel. I didn't see any negative effects of mounting it just 7" away from rear wall. (May be I'm unable to judge)

But clearly left and right channels are in boxes, and they are giving a lot more bass compared to center. But it really doesn't matter for me, because its giving very good and clear vocals. That is all I expect from movies. So my center channel is success !!!

Secondly, the sounds that come from center are different from the ones that come from left and right. So I'm unable to clearly compare.

The right approach for comparison would be to make two OB style center channels, and use them as my left and right. Then Il get a clear differentiation between how the same driver performs in boxes Vs a simple baffle like OB.

One thing is clear....low end is surely more in boxes. And branded center channels sounded a little more refined, and soft. Buy Ahuja is sounding a bit raw.

Buy as a center channel @ 2k price, it exceeded my expectations !!!!
 
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#16
Third, they involve large woofers, mostly 15”. Try replicating it with smaller drivers, even if more in number, you will have no low end.
Why is that so? Does it matter how the target SPL is reached? A pair of 15" with 5-8 mm xmax and 40hz capability can be equaled (or exceeded) by multiple smaller drivers.

Pro audio line arrays just wouldnt work otherwise.
 
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yogibear

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#17
Why is that so? Does it matter how the target SPL is reached? A pair of 15" with 5-8 mm xmax and 40hz capability can be equaled (or exceeded) by smaller drivers.

Pro audio line arrays just wouldnt work otherwise.
It’s pretty hard to get that OB bass with multiple smaller drivers. It’s just not enjoyable at all. The height of setup increases and returns are not as great as with larger driver.

OB line array is different setup altogether and it comes with its own set rules to be followed.

Pro audio LA are boxed. Easier to manipulate.
 
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