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Risers I built wrong 10 years ago, help? (1 Viewer)


Stunt Coordinator
Oct 27, 2004
Auckland NZ
Real Name
Murray Thompson
10 years ago I built two risers that were totally sealed inside, now covered with rubber underlay and carpet glued to the chipboard flooring. I never filled them with insulation and didn’t add any ports, back then I didn’t know this was standard practice. I have 4x 18" ported PSA subs up front and when I have very deep base sometimes I feel/hear a resonance coming from under the seats. This isn’t always its just some deep bass that it happens, however I’m the only one that would know in the family. I believe today the situation I have is due to the drum effect is coming from the risers being fully sealed.

I’ve since been told if I open up the areas with ports say under the seats the "drum" under the seats would then be open and the resonance may improve. At this stage my problem is I don’t know where the timber joists are as I never took pictures of that, all I have is these below. One I have marked in red where the chipboard joins are and the few screw holes I can see. I’ve asked the builder but after 10+ years he cant quite remember.

What do the experts here think please?
I asked the question on another forum but before I start trying to cut holes through glued on carpet and rubber underlay I need more advice. I don’t need these risers to become tuned bass traps, I just don’t want to go into all that side of things as I know its more complicated. I’ve been told if I make ports large enough under the seats in each area between joists the risers would become like a broadband trap, that’s on by me.... Then I would EQ after with my Room Perfect from my McIntosh MX160.

Your thoughts are greatly appreciated.

Your thoughts are greatly appreciated.


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