[jimbones]

I am building a dual 12 OB woofer. I want to take it up to 275hz. Is there much difference between these 2 configurations considering I am taking the XO point up fairly high.Thanks in advance for your recommendations.

[JohnH12]

I'd have to see your interpretation, but generally little difference.  The concern is cavity resonances.  If the cavities are similar so are the resonances.  You can use Horn Response to model.  Martin King had a neat little formula in one of his white papers to do an approximation of the cavity resonances.

[jimbones]

I decided on building the GR research W frame. I called Danny after posting this thread and he said they are virtually the same. I thought I remembered reading somewhere that if you take the woofers up  higher ( say 275hz ) like I am doing, the W frame caused a problem. Maybe not. I want to maintain a certain height as i want to put the amp under it.

[JohnH12]

You will certainly be in the potential resonance area.  How are planning to eq the system?  Resonances can be difficult to remove.

[jimbones]

John, I will be using the Rythmik amp (A370?) It has a para EQ in it.

[soundbyte]

Hello,

After quite some time trying out many different OB bass configurations I settled on the V frame, which is similar to the W frame but without side panels, see photo.




H frames that I have tried have had cavity resonance issues coming from the area between the drivers and the flat rear wall.

Russell.

[matevana]

H frames that I have tried have had cavity resonance issues coming from the area between the drivers and the flat rear wall.

Russell.

This makes sense to me. Now if you mounted both woofers from the back, you could reduce the opening of the V and play with the time alignment by increasing the velocity of the front wave.  You may be able to alter the cancellation properties to your advantage in the design.