I think your sims may contain 2 key errors.

First, it doesn't look like your frd files include baffle diffraction. You have said they do but if they did, your final SPL on the sub should be closer to 85dB if you include the full 6dB of baffle step loss and closer to about 88dB if you only include about 3dB of loss. Your sims are still sitting up at about 90/91dB. Baffle diffraction effects should also be included with the tweeter and mid too.

Second, you need to include the driver delay (found in the 'Tune' menu) in XSim for the phase of the drivers to be correct. In XSim, this is a combination of the difference in acoustic centers between the drivers and the difference in path length to the listener due to the different placement of each driver on the baffle.

So for baffle step loss with your sub, being so large and therefore needing a rather wide front baffle, I might guess about 3-4dB of baffle step loss might be what you need to shoot for. J Bagby's Frequency Response Modeler - http://audio.claub.net/software/jbabgy/FRM.html - will do the diffraction sims for you and also allow you to alter the amount of baffle step loss. Model your sub in the diffraction section at the bottom, add it to the Register above, find the 'Baffle Step: Simple Step or from Below' up near the top left corner, turn the 'Off' button to 'Inverted', and then change either the '% Step' or the 'Step dB' amount to suit. But it's an Excel spreadsheet, so you'll need MS Office to start off with. Response Modeler will also add the diffraction to your original FR curves, splice in the box curves, modify your impedance curves and extract minimum phase from both your frd and zma files which are all necessary steps in the process.

The acoustic center (AC) of a driver is more or less the physical point where sound waves originate from on the driver and it is hard to guestimate this right. Generally, it's at about the point where the cone meets the voice coil. For the purpose of sims, you basically have to just physically measure this point based on the manufacturer's drawings. Save the specs to a pdf file and then zoom it out to life size. Then physically measure on your screen from the front edge to the cone/coil intersection, which is often usually where the spider sits too. To actually get the real AC points, you need to measure the drivers on baffle with a mic.

So with a tweeter, you might use the depth of the face plate as the AC point, but with a waveguide included on your selection, it's going to be further back than that. Looking at the drawing for the Wavecor, I'd probably guess it's somewhere between 25-30mm back. Do the same with the other 2 drivers. Now what you input into XSim is the difference in path length from the listening position to the tweeter and then from the listening position to the mid and to the woofer which are just simple a(squared) = b(squared) + c(squared) equations. Choose a listening point 1m out from the tweeter on axis. This plus the 25-30mm is the distance to the tweeter AC, call it 1028mm. Now draw 2 right angle triangles starting from that same 1m point on the tweeter axis that go to the mid's AC and that go to the woofer's AC and then calculate the respective distances from that same listening point to each driver's AC, which is the length of the triangles' hypotenuse. Now subtract the distance to the tweeter from the distance to each of the other 2 drivers.

Now in XSim, leave the tweeter delay at 0 but depending on where you place them on the baffle, I expect the extra distance to the mid to be small, perhaps about 1" but the extra distance to the woofer to be fairly large, and I'm just guessing here, maybe between 4-6". Finally, in the FR chart under 'Curves', turn off the System phase and turn on each of the drivers' phase. Now what you are trying to do is get a flat FR while at the same time getting the driver phases to align in the 2 xo regions. Hopefully that should get get you set up more accurately now to start off with.

First, it doesn't look like your frd files include baffle diffraction. You have said they do but if they did, your final SPL on the sub should be closer to 85dB if you include the full 6dB of baffle step loss and closer to about 88dB if you only include about 3dB of loss. Your sims are still sitting up at about 90/91dB. Baffle diffraction effects should also be included with the tweeter and mid too.

Second, you need to include the driver delay (found in the 'Tune' menu) in XSim for the phase of the drivers to be correct. In XSim, this is a combination of the difference in acoustic centers between the drivers and the difference in path length to the listener due to the different placement of each driver on the baffle.

So for baffle step loss with your sub, being so large and therefore needing a rather wide front baffle, I might guess about 3-4dB of baffle step loss might be what you need to shoot for. J Bagby's Frequency Response Modeler - http://audio.claub.net/software/jbabgy/FRM.html - will do the diffraction sims for you and also allow you to alter the amount of baffle step loss. Model your sub in the diffraction section at the bottom, add it to the Register above, find the 'Baffle Step: Simple Step or from Below' up near the top left corner, turn the 'Off' button to 'Inverted', and then change either the '% Step' or the 'Step dB' amount to suit. But it's an Excel spreadsheet, so you'll need MS Office to start off with. Response Modeler will also add the diffraction to your original FR curves, splice in the box curves, modify your impedance curves and extract minimum phase from both your frd and zma files which are all necessary steps in the process.

The acoustic center (AC) of a driver is more or less the physical point where sound waves originate from on the driver and it is hard to guestimate this right. Generally, it's at about the point where the cone meets the voice coil. For the purpose of sims, you basically have to just physically measure this point based on the manufacturer's drawings. Save the specs to a pdf file and then zoom it out to life size. Then physically measure on your screen from the front edge to the cone/coil intersection, which is often usually where the spider sits too. To actually get the real AC points, you need to measure the drivers on baffle with a mic.

So with a tweeter, you might use the depth of the face plate as the AC point, but with a waveguide included on your selection, it's going to be further back than that. Looking at the drawing for the Wavecor, I'd probably guess it's somewhere between 25-30mm back. Do the same with the other 2 drivers. Now what you input into XSim is the difference in path length from the listening position to the tweeter and then from the listening position to the mid and to the woofer which are just simple a(squared) = b(squared) + c(squared) equations. Choose a listening point 1m out from the tweeter on axis. This plus the 25-30mm is the distance to the tweeter AC, call it 1028mm. Now draw 2 right angle triangles starting from that same 1m point on the tweeter axis that go to the mid's AC and that go to the woofer's AC and then calculate the respective distances from that same listening point to each driver's AC, which is the length of the triangles' hypotenuse. Now subtract the distance to the tweeter from the distance to each of the other 2 drivers.

Now in XSim, leave the tweeter delay at 0 but depending on where you place them on the baffle, I expect the extra distance to the mid to be small, perhaps about 1" but the extra distance to the woofer to be fairly large, and I'm just guessing here, maybe between 4-6". Finally, in the FR chart under 'Curves', turn off the System phase and turn on each of the drivers' phase. Now what you are trying to do is get a flat FR while at the same time getting the driver phases to align in the 2 xo regions. Hopefully that should get get you set up more accurately now to start off with.

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