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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
cissado
113 posts
 
I think Acoustic Fields builds something similar to what the op is referring to. A diaphragmatic absorber. They do or used ro sell plans for them to diy. Its pretty complex with a carbon substance inside as well, if I remembercorrectly. I believe they work with the lowest of bass frequencies. They are big, heavy and expensive. 

The flex part of the box is a perforated piece of wood sandwiched in between the multiple layers of the box. There's not much products that can compete with its effectiveness at those low levels of bass. 
oldhvymec OP
5,101 posts
 
That's the purpose of the adjustable spring bass traps. 125 hz and <

As far a DBA or Swarm they are the bandaids. The whole reason they were developed to begin with. I got away from multi subs a long time ago 20 plus years now..  I use 2 sometime 3 OB dual servo subs with full blown DSP controlled MB columns. There is not a gear issue ONLY a room issue. I confess...:-)

It is an easy way to even out the peaks and valleys BUT still not the best.

I like a servo sub system with Narrow MB and Monitor columns. There is no need for BASS everywhere, when it's RIGHT there.. A lot of the nulls are corrected by MB column placement.  The servo software is pretty good BUT it is software none the less.. Just like the DSP.. Not all DSP software is created equal. I use a Behringer 2496 for all the BASS management.. Easy peasy.. Active sound management, I just use it for 300 hz and down.. 300 hz up its all passive.

This is the PRE check list for a front room. Not the main room but it is my main listening room for now.. Paint, floors and drapes. They are going to be made. CLOSE.. Drapes and traps. of course there is a phono stage on the way.. 3 more months.. I'm cutting it close..

Thanks for your input though, rhljazz
rixthetrick's avatar
rixthetrick
1,060 posts
 
@oldhvymec - I did find a broadband absorber, designed by Dennis Foley of Acoustic Fields.
He uses a sealed box, with perforated internal walls filled with activated charcoal.
I have visited the Genolan caves in New South Wales and the caves are used for concerts and recordings beacause of the acoustical properties of the porous limestone formations.

https://www.acousticfields.com/product/acda-10-studio/

It uses activated charcoal within the cabinet, the micro pores do the heavy lifting. When I first read it, I remembered the caves.

He does sell plans for DIY. Currently I am building four of his QRD17 diffusers (from plans) out of solid cherry wood.
oldhvymec OP
5,101 posts
 
How cool is that.  I use to use AC and DE in HUGE water filtration systems.. 12,000 gallon filters. We uses two frack tanks as holding and settling cells. That is when I learned about concrete and it ringing like a bell.

It took quite a few super sacks of AC to fill the two 5000 gallon stainless steel filters. It cost 15k 30 years ago for 15 super sacks. Had to turn in a core carbon too, or the price almost doubled..

I wonder how thick it has to be to BE effective? I'll check it out..

Regards
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