Isolation platform for subwoofer? - Page 4 - Home Theater Forum and Systems - HomeTheaterShack.com

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post #31 of 32 Old 07-14-08, 04:10 PM
mas
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Re: Isolation platform for subwoofer?

Quote:
thewire wrote: View Post
So you are recommending that I:

1: Remove my subwoofers from subdudes
2: Place sticky foam feet the size of quarters on the subwoofer
3: Place the subwoofer on the concrete floor, or plywood (insualtion filled) riser.
4: Permanantly seal my PVC ceiling to reinforce it from vibration (as instructions note) prior to wiring my equipment to their home.

Result -

1: I will have less support for my subwoofer
2: I will have wires running across my floor

Lets say the OP takes your advise and does his floor over

Result -

1: Subwoofer will have unknown improvement. We don't know what the cabinet is
2: Maybe he needs to hire a builder, get permits, all to fix something that is already fixed. Not going to be high WAF if that is of importance. I'm sure the OP is intellegent enough to know that securing something that will rattle will stop it from rattling. Hopefully he is not treating room modes.



First,reading your interpretation of my prescribed(sic) course of action!

My suggestion was to fully analyze the situation and identify the nature and source of the real problem...not to begin with a commercial product and look for a problem it will solve. Pending that evaluation, many courses of action may be available; resulting hopefully with the one that best suites the situation and the means being chosen.

It seems that your fundamental problem is the structural integrity of the floor (as DrWho suggested). The truly prudent course of action would be to address this problem - before you touch anything in the audio signal chain.



Failing that, mechanical de-coupling can be achieved via the use of a sheet of Sorbothane placed between rigid surfaces tightly coupled to the floor and subwoofer. Be advised that this will NOT remediate LF acoustical coupling via emitted acoustic energy.

I have no idea to that which you are referring with regards to "sticky foam feet the size of quarters".

And you have lost me a bit regarding your reference to "sealing your PVC ceiling...". (PVC?)

If your ceiling suffers from the same structural problems as the floor, then the prudent thing would be to appropriately stabilize it as well. Sealing it may help a bit in minimizing some 'rattles', but the main benefit of sealing the ceiling (aside from possibly helping to keep out water ), will be to help mitigate a flanking vector for sound ingress and egress relative to sound transmission issues...


If the identified problem is indeed the structural stability of the floor, the improvements will reduce the involvement of the floor regarding the negative effects of vibration, and to a degree, minimize secondary radiation of acoustical energy.

Regarding the "less support for my subwoofer" and the assertion that the "Subwoofer will have unknown improvement."...

Addressing the floor and ceilings structural stability may indirectly improve the apparent bass response by removing a secondary virtual source of some vibration, rattles and radiation of resonant acoustical energy. But this in itself is not designed to improve your subwoofer! The apparent response may improve. But improving your subwoofer is a completely different problem suitably addressed independently of your problem with the floor and ceiling.

(Regarding the subwoofer itself... As DrWho mentioned, ideally, the speaker should remain locked in position with the only dynamic element being the driver cone! But as also mentioned, if minuscule (non-resonant) movement of a cabinet resulting in small group delay errors is considered significant, then we need to back up and address several much larger issues! This is another entire can of worms!)

And regarding whether you will have wires running across your floor...That is a function of your chosen installation technique. I do not see this as being a necessity regardless of the associating conditions, but you just might have exposed wires if that is how you choose to install the system...

And regarding: "Maybe he needs to hire a builder, get permits, all to fix something that is already fixed. Not going to be high WAF if that is of importance. I'm sure the OP is intelligent enough to know that securing something that will rattle will stop it from rattling. Hopefully he is not treating room modes."

As far as what they are really addressing...I must admit to using a differing method to identify problems. One aspect of this methodology is by evaluating the situation using simple experiments that alter a known variable in a controlled manner and effectively evaluating the results.

The other aspect is that, while experience enables me to cut to the chase in many instances via simple pattern recognition, the fundamental means of evaluation is via the use of a TEF analyzer. Room modes, structural transmission/re-radiation/vibration. NLA techniques, and other tools to evaluate the nature of problems and the effectiveness of solutions are readily available. I suggest using them!

The cabinetmaker's adage of "measuring twice and cutting once" is a good one and definitely applicable to things acoustic.

I am neither telling you or whomever that his floor is the problem. This information comes from you folks! If it is incorrect, hey, I am merely exploring options based upon provided information, NOT first hand evaluation.

As far as the tools for anchoring general household goods during earthquakes, many folks are not at all aware of their existence unless they have lived in an earthquake prone zone. And still, even then, many are not aware of them. I don't know many in, say, Michigan who use them!


So, this notion of guessing, doing a lot of work, and then guessing again if they were wrong, implies that we are guessing as to the source of the problem as well as to the solution and simply reacting - and that, I would contend, while perhaps building character, is a waste of time and money.

I prefer (and cannot too adamantly suggest!) proper evaluation and planning, combined with results driven feedback and proof of performance verification... Not just buying some new whiz bang market solution 'guaranteed to cure what ails ya' and plugging it in. And that is where this thread began.
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post #32 of 32 Old 07-14-08, 05:23 PM
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Steven
 
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Re: Isolation platform for subwoofer?

Quote:
mas wrote: View Post
I prefer (and cannot too adamantly suggest!) proper evaluation and planning, combined with results driven feedback and proof of performance verification... Not just buying some new whiz bang market solution 'guaranteed to cure what ails ya' and plugging it in. And that is where this thread began.
I see and my bad. I never would have gotten invloved knowing so. Thanks.
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