Speaking of my experiences, I stuck with the clamshell configuration because in my room, any kind of baffle...H, U, S, W... increased the bass output, but in a bad way: ie, by pressurising the room, bringing out the modes, resonances, etc....so the subjective bass quality with the clamshells is the best I have experienced with my setup, in my room.
Were you able to test it in a simple flat baffle? That was said to be the equivalent of having the two drivers in a clamshell configuration.
Yah...that's how I used the driver for years.
I did post a diagram earlier showing the difference between the output of a single driver and clamshell arrangement. With the single driver, the output spreads everywhere. With the clamshell, there is cancellation at the sides....so there is more directivity. Although output is reduced, so are incitements to room modes.
With my single baffled bass driver, a bass null was created in my listening position. I had to move the sofa forwards 2' to get any bass. No such issues with clamshell, and bass is even everywhere in the room both in volume and throughout the frequency range.
I did post a diagram earlier showing the difference between the output of a single driver and clamshell arrangement. With the single driver, the output spreads everywhere. With the clamshell, there is cancellation at the sides....so there is more directivity. Although output is reduced, so are incitements to room modes.
With my single baffled bass driver, a bass null was created in my listening position. I had to move the sofa forwards 2' to get any bass. No such issues with clamshell, and bass is even everywhere in the room both in volume and throughout the frequency range.
I'm confused by the woofer arrows on the right hand drawing. I don't see how the null is created beyond the confines of the woofer, and it wouldn't be a null it would be isobaric. I don't see any difference between the double woofers out of phase than a single woofer. I think the arrows are incorrect. The outside arrows are pointing away from the clam shell but the two internal woofer arrows are moving the same direction. The top woofer arrow is backwards.
I think woofers in a clam shell in phase with each other would create a strong wave around the radius of the clam shell. This would make a stronger cancellation line than if the woofers were placed on a flat baffle. This might work well in smaller rooms.
How does one align these with the midrange for delay? If the woofers are making in phase sound from the front and back how do you integrate the midrange that is making in phase and out of phase sound?
So they are isobaric without a box? How does that create a null? OK, are they in phase or out of phase?
They are in phase with each other, the cones move in the same direction. If you start reading around page 11-12 it might be more clear.
@Arthur Jackson ,
I wonder too. And I have no knowledge about that. If speaking below 80 hz where the ears have less acuracy to locate those frequencies comming from a point source :
First : quality of sound vs a H-Frame or a Ripole (which extend around 10 hz below the Fs at the cost of efficienty) VS a Clamshell with no box.
I am assuming at believing experienced diyers than tried everything, that the SQ is winned on : shorter distance for the cancelation due to the lack of paneel surface. And maybe less emiting sound from the panel as there are none ?!
Second, the clamshell behavior with 2 drivers VS same drivers also nude but firering both towards the listener. SQ difference due to the patern only or same.
then theoricaly, only acoustic wise what about only one driver of the same Sd than the two littlierone ? Will we percieve a different SQ.
Really wonder if a ripole of two 12 or a H-Frame with a 18"performs the same below the acoustical resonances of the box, than boxless at iso drivers surface.
I wonder too. And I have no knowledge about that. If speaking below 80 hz where the ears have less acuracy to locate those frequencies comming from a point source :
First : quality of sound vs a H-Frame or a Ripole (which extend around 10 hz below the Fs at the cost of efficienty) VS a Clamshell with no box.
I am assuming at believing experienced diyers than tried everything, that the SQ is winned on : shorter distance for the cancelation due to the lack of paneel surface. And maybe less emiting sound from the panel as there are none ?!
Second, the clamshell behavior with 2 drivers VS same drivers also nude but firering both towards the listener. SQ difference due to the patern only or same.
then theoricaly, only acoustic wise what about only one driver of the same Sd than the two littlierone ? Will we percieve a different SQ.
Really wonder if a ripole of two 12 or a H-Frame with a 18"performs the same below the acoustical resonances of the box, than boxless at iso drivers surface.
It is open baffle with no baffle. It is unwise IMHO. It doesn’t increase directivity it just decrease output. The output in such configuration more or less the same one driver naked or two. The benefit of two just to reduce distortions. But any w frame force cancelling is better solution. You increase spl, reduce distortion even more.
Is distorsion still there at iso Sd or is it just about odd order push pull cancelation ? In this scenario, it is not because the cabinet and should work with push pull nudes as well ?
This has nothing to do with this thread.
As I stated earlier, page 11-12 shows the clamshell with a gap between the drivers has the same 6dB increase as two drivers side by side.
Yes. Just even not odd order should be cancelled.
You are saying that if you would move one driver sideways without changing anything else the output stays the same?
Clamshells design has about half working surface area less compared to side by side. I don’t see theoretical reason to be the same output. Do you have measurements supporting this claim?