Mixing Sealed & Bass Reflex Subs, Phase Adjustments?

Hi all,

Is there an elegant simple solution to applying a filter of some kind in a DSP (such as MiniDSP HD 2x4) to adjust phase from a frequency range on a sealed sub so that its easier to integrate with bass reflex subs? I'm trying to flip the phase of a sealed sub in the 10hz to 25hz range (unless it would be easier to flip the frequencies above it, and then just invert it in the DSP). I was reading about all pass filters. And reading about other methods, but they're beyond complex. Surely there's a more simple way as this is not for a full range speaker but just for a very limited range such as with sub frequencies (10hz to 100hz or so total).

I have a Umik-1 USB microphone, MiniDSP HD 2x4 and some basic use of REW at disposal.

Edit: Surely it's not as simple as using RePhase plugin and using the parametric phase sliders to adjust phase -180 degrees in the ranges I want and just generate and import into miniDSP FIR on the channel output?

Very best,
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diyAudio Moderator
Joined 2008
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If you put two subs side by side, one reflex and one sealed, then it should be as simple as getting their responses the same. Then phase will also be the same.

I think that answers the first part of your question.. however the room changes what you'd see. Furthermore, and because of the same circumstances, we don't always want the subs to have the same contours when creating a multi-sub array.
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Thanks Allen,

This room has 3 subs in it that are all DIY. Two are bass reflex tuned at 20hz, the 3rd is a new one and is sealed. When I align them in the room, depending on the delay and inverting (term from MiniDSP menu, I think its just polarity in reality? Or is it an actual 180 degree phase shift?), I can get net summation for most of the range. The critical range that I'm trying to align best, however, is the 10hz to 25hz range basically. I know the port's of my bass reflex are not the same phase as the drivers and they're peaking at 20hz. Two of these subs are side by side behind my seating and slightly to the left of the room. The 3rd is on the front wall in the left corner.

Even if that's all I need to do and there's nothing else to it, I can live with that.

But, it would still be helpful to know if there's a basic solution for applying a frequency range phase change, even just for experiment sake?

Very best,