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Adjustable Spring Bass Traps

If a standard basket / cone speaker can produce a certain frequency, can the same design collect a certain frequency?

I want to design an "Adjustable Spring Bass Trap", with passive radiators as the collectors..  I need to do some tinkering.

We use to call something that took vibration and surge out of hydraulics an accumulator or better known as a shock absorber.

I have a pair of 12 cubic foot columns 1.5" thick 60 x 22 x 18".

I have 8 12s, 4 15s and 4 18" high excursion radiators. I think 1 12, 1 15" and 1 18" will do the job.

I think if they were concave with no dust cap or inverted dust caps that would improve collection.

Do I port the the passive radiator? Seems weird to port a port, or will the box just collect bad BASS so to speak?

Do I hang dingle berries inside to dampen the "BAD BASS"? I'm thinkin', I think.. Could just be my OCD kickin'

1/2" rubber rope inside going through eyelets, 20 or 30 will do. Terminate the rubber rope with hog rings or zip ties.
Can I adjust the rubber rope to collect "Bad Bass" too?

An IB design, a ported design, and active design, that uses an active speaker to react to "BAD BASS"?

Me the dog and the rabbit (Junior) got an idea, I haven't let the chickens in on yet.. 

What do you think? 
oldhvymec
oldhvymec OP
5,101 posts
 
What about a sub with a spring bass trap built in?

Oh no name callin’ other than the normal name callin’, just sayin’

Regards
erik_squires
16,121 posts
 
Yes, but the hard part is making the trap cover a large enough surface area. Sucking all the 20Hz out at a 1'x1'x1' cube in the room isn't nearly as effective as say floor to ceiling corner trap.
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auxinput
2,920 posts
 
This idea could work.  You definitely want it in a sealed box (vented won't do the same thing).  You will need to put some sort of damping material on the inside back wall to cushion the "woofer spring" and increase the bass trap bandwidth.  The hard part here is trying to determine the "weight" of the passive radiator.  You can try to use a tuned membrane bass trap calculator, but you'll need to figure out the "weight per square inch" of the passive radiator.  Then it's the volume of the internal cabinet.  I think it's much easier to engineer a tuned membrane bass trap because the area of the membrane matches the area of the box and the entire membrane has equal distance to the back of the box.  Not saying this can't be done, but it is entering into engineering rocket science here.

I have only seen one active bass trap made and it is called "Active Bass Trap" made by a company called Bagend.  It is similar to the type of technology you find in noise-cancelling headphones.  It uses a microphone mounted on the front of the cabinet and then uses a small amp with a 10" woofer to create the opposite "cancelling" waves.  I have read that it's somewhat effective.  You may need 2 or 3 of these.

You may be better off doing a design where your rear corner subs are fired in opposite polarity of your front subs.  I forget what this is called (something like "double-bass" or something).
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