I was looking at your sweeps in REW, and noticed they were over 95dB. That may not be an issue, but you can sweep at a much lower SPL, if in a quiet environment.
I did notice a peak in 2nd order distortion on the mid around 1.5k. It shows both on and off axis. The tweeter measured considerably better at 1.5k. Sometimes a loose mounting screw can cause such a thing. I think an overly tight screw can as well. My driver baskets are thick aluminum. I usually tighten the screws with a minimal amount of torque. The ideal tightness may vary with several factors.
I did notice a peak in 2nd order distortion on the mid around 1.5k. It shows both on and off axis. The tweeter measured considerably better at 1.5k. Sometimes a loose mounting screw can cause such a thing. I think an overly tight screw can as well. My driver baskets are thick aluminum. I usually tighten the screws with a minimal amount of torque. The ideal tightness may vary with several factors.
I was indeed aiming to be near 95dB as I thought this is the common level for checking distortion. Also, I was wary of noise (wind, birds, passing cars and planes), so avoided lower levels, rightly or wrongly. I was getting about 45-51dB headroom readings during REW sweeps.
I was cautious when bolting on the drivers. I am sure they are well attached but not overtightened.
Give it a shot.
It depends on how you setup the optimizer. The way I showed, the output is a blend of on and off axis (in-room), so the optimizer will move the crossover frequencies a little bit, but not much. When I've run it then put the frequencies back it doesn't do much with your design.
If you heavily weight on-axis (or only optimize for it, maybe since you only have an on axis measurement) then it may move the x-over frequencies around and end up screwing up the off axis response.
It depends on how you setup the optimizer. The way I showed, the output is a blend of on and off axis (in-room), so the optimizer will move the crossover frequencies a little bit, but not much. When I've run it then put the frequencies back it doesn't do much with your design.
If you heavily weight on-axis (or only optimize for it, maybe since you only have an on axis measurement) then it may move the x-over frequencies around and end up screwing up the off axis response.
So what's the thinking on using EQ to smooth out narrow peaks and dips in the mid-range? Is the processing sufficient to allow very much? Does it negatively affect sound quality if over done? The reason I ask, is because I was looking at the polars for my sim, and I see a spot or two where I think adding 3dB or more at a Q of around 3 would improve both on, and off axis. Does the optimizer do any of this, if allowed in its setup? Would this just be overkill? I kind of think it would be, but it is interesting.
For example, look at 1.6k and 2k. These two dips are consistent as you move off axis. I assume that if you EQ them on axis, they will also smooth out off axis. These are coming from the mid. I know they are very minor. If the tweeter was crossed below 2k, they would likely be filled by the tweeters response. This is mostly a hypothetical question. I do not usually look at polars, but I think I'm beginning to see why others are fascinated by them.
For example, look at 1.6k and 2k. These two dips are consistent as you move off axis. I assume that if you EQ them on axis, they will also smooth out off axis. These are coming from the mid. I know they are very minor. If the tweeter was crossed below 2k, they would likely be filled by the tweeters response. This is mostly a hypothetical question. I do not usually look at polars, but I think I'm beginning to see why others are fascinated by them.
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If you like playing, try this filter. My suspicion is that the polar will be smoother.
Woofer LR4 @ 400
Mid BW4 @ 400 and BW3 @ 2300
Tweeter BW3 @ 2500
EQ
W -4dB @ 250 Q=3
M +1dB @ 550 Q=4
M +3dB @ 725 Q=4
M +3dB @ 1600 Q=4
M +3dB @ 2000 Q=4
M -10dB @ 4500 Q=4
T No EQ
Levels
W +3dB
M -8dB
T -7dB
Woofer LR4 @ 400
Mid BW4 @ 400 and BW3 @ 2300
Tweeter BW3 @ 2500
EQ
W -4dB @ 250 Q=3
M +1dB @ 550 Q=4
M +3dB @ 725 Q=4
M +3dB @ 1600 Q=4
M +3dB @ 2000 Q=4
M -10dB @ 4500 Q=4
T No EQ
Levels
W +3dB
M -8dB
T -7dB
The dips seem consistent on and off axis, so that would lead me to believe that they are not diffraction related. Neither woofer, nor tweeter show dips at the same frequencies, so that leads me to think that it's not a measurement error, like a mic response error. It still could be an illusion. I've encountered some REW measurement issues with my sub that defy logic, so mostly I go with what sounds good to me.
Could I hear it? Probably not, but the frequencies involved are in the range where my hearing is likely pretty sensitive, so maybe it would be a subtle placebo type improvement.
I'm mostly looking so closely at this as a theoretical exercise, and to lean how to interpret the polar graph. My speakers are not usually designed using a sim at all, and they are passive designs. I sometimes use a sim to calculate a notch, or sometimes shape a roll-off that's problematic. I use trial and error, and lots of measurements, and listening.
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You're thinking polars in the sense of smooth. Which is not what they are useful for in my opinion. You could after all hammer the response flat as a board with a FIR filter. So what.
Look at your x-over design, at the polar from 2khz to 5khz. You should be able to easily see that the dispersion narrows at the cross over and then gets wide again at 5khz. This is what causes the estimated in-room response to dip at the cross over and then bump up at 5khz.
You can either sacrifice on axis behavior to counter act this. Or, change your crossover design to not get off axis cancellation in the crossover region.
Look at your x-over design, at the polar from 2khz to 5khz. You should be able to easily see that the dispersion narrows at the cross over and then gets wide again at 5khz. This is what causes the estimated in-room response to dip at the cross over and then bump up at 5khz.
You can either sacrifice on axis behavior to counter act this. Or, change your crossover design to not get off axis cancellation in the crossover region.