Subwoofer Fore/Aft Positioning (Latency) Alignment Relative to Speakers.

[howdomagnetswork]

Hello everyone.

This topic goes into what I perceive as relative semantics when applied to a medium-sized room setting (vs. critical live event speaker time aligning) but I have a burning curiousity. I have a new sub using one of the typical settings: DAC interface -> sub -> studio monitors. My previous subwoofer had a forward-facing speaker with a port at the front. My new sub is downward firing with a port up front.

1) Would it be safe to assume, in an open space (or with no room boundaries present), that a forward-facing + port subwoofer moved 2"-4" forward/backward could introduce time alignment issues in terms of hearing mid-higher frequencies first and bass too late? This is also assuming somehow phase between all 3 sources would be remain equal (I'm still a newbie in understanding how bass waves propagate).
- From looking at the side, my first subwoofer cone was about 2" ahead of my monitors.

2) Now, my new setup has a downward firing cone but ported up front. We all know bass frequencies are perceptually omni-directional but still are a source point of sound. Where does max spl happen/originate, at speaker or at port? Or is port just a function to achieve higher levels? Based on that, should my subwoofer be now placed more closer to me/in front of monitors due to dimension changes?

3) I'll have to go on REW to test, but given if there are delays in sub bass response (20hz-80hz) (to your ears) dependant on positioning, wouldn't it make sense to place subwoofer at a corner of the front wall within a room so while you get build up of bass, bass reverberation/delays you hear should be reduced?

On top of my head this sounds trivial, but for personal reasons, I would love to learn about this. Thank you.

 

[alex-z]

The direction your subwoofer driver + port faces is almost completely irrelevant. It certainly won't interfere with your mid-range unless you completely mess up the crossover point. A typical 80Hz 2nd order low-pass will have you 24dB down by 320Hz.

The port only resonates at the tuning frequency. Over the majority of the operating bandwidth, the acoustic centre will be the driver.

Your subwoofer should be placed wherever gives you the smoothest frequency response at the listening position. Then you time align the subwoofer with the speakers. That way when you apply the low-pass and high-pass filters, the summation should be perfectly smooth. Our ears are insensitive to delay at low frequencies, so the biggest concern is the crossover region itself.