Been working on (really wide) baffle design for a passive open-mid TMW, and have finally settled on driver placement, spacing and edge treatment:

I went with a 22.5 degree angled edge to minimize the midrange dip above 1kHz and flatten out the response between 2-3kHz (and because I think it looks better than a really large radius roundover). Since Paul V's Baffle Diffraction Simulator does not do open baffles and Jeff B's Baffle Diffraction & Boundary tool does open baffles but not chamfered edges, here is how I modeled it:

The XO does not look too bad, at least in simulation-land: 14 components, 2nd order electrical all around, except the midrange low-pass, which is 3rd order electrical. The tweeter and woofer both have resistors resistors for padding and there is a notch to deal with the midrange hump at 400Hz. I'm crossing at 280 and 2500Hz.

Impedance drops quite low but impedance phase looks OK, staying within +/- 60 degrees:

I plan to use baltic birch baffles with exposed edges. I just need to figure out how to do the joinery for the angled wings...rabbets maybe?

I went with a 22.5 degree angled edge to minimize the midrange dip above 1kHz and flatten out the response between 2-3kHz (and because I think it looks better than a really large radius roundover). Since Paul V's Baffle Diffraction Simulator does not do open baffles and Jeff B's Baffle Diffraction & Boundary tool does open baffles but not chamfered edges, here is how I modeled it:

- Modeled the mid on open and closed baffles in Jeff's tool and saved both FRD results
- Used the 'subtract' function in Frequency Response Combiner and got the delta between the two
- Modeled the 3" chamfer in Baffle Diffraction Simulator
- Used the 'add' function in FRC to combine the chamfered baffle response with the delta diffraction signature

The XO does not look too bad, at least in simulation-land: 14 components, 2nd order electrical all around, except the midrange low-pass, which is 3rd order electrical. The tweeter and woofer both have resistors resistors for padding and there is a notch to deal with the midrange hump at 400Hz. I'm crossing at 280 and 2500Hz.

Impedance drops quite low but impedance phase looks OK, staying within +/- 60 degrees:

I plan to use baltic birch baffles with exposed edges. I just need to figure out how to do the joinery for the angled wings...rabbets maybe?

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