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How delay/gain affect subwoofer interaction (1 reply)

Jonas Johndal Hansen
4 years ago

This might be a high-level question, but I hope to get a discussion started about the topic. At least the basics of the theory.

Having a subwoofer center front and center back of the room will put the virtual sub in the center of the room thus mitigating the corresponding room modes.

What happens if delay is added to the rear subwoofer? How will the modal plot change? 

And same question if gain is added to the rear subwooer. How will these changes affect the modal plot?

The concept is used in Harman's SFM algorithm to improve seat-to-seat consistency, but to my knowledge they are brute-forcing until optimal parameters are found. What I would be interested in was a methodology to use in case where the client's room does not allow optimal placement of subwoofers - could delay/gain change the behavior of the subwoofer interactions to accommodate this? (By accommodate I do not mean as a perfect replacement for optimal positioning - but to optimize under the given circumstances)

Bob R
4 years ago
Bob R 4 years ago

I don't know any way other than the brute-force method to determine this, but a predictive approach certainly does seem like it would be a useful solution.

fwiw I still drag around an old, heavy (and arguably anachronistic) AudioControl Iasys HT analyzer just for its ability to measure distances to the "acoustic centers" [sic] of different subwoofer drivers and define time offsets with sub-millisecond accuracy in order to align them.

I haven't produced modal plots of the entire space before and after time-aligning the subs, but as far as the measurements from the money seat go using delay this way is the only solution I've found for compensating for less-than-ideal subwoofer locations.

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