# Do I even need bass traps at all?



## Talley (Dec 8, 2010)

See my waterfall.

I put up some poly panels and they resonate... it introduced a 70hz problem. I'm ordering some dynamat product to stick to the inside of the poly panels to deaden them. 

But beyond that do I even need to look at bass traps at all? I have zero bass traps.


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## Talley (Dec 8, 2010)

Here's why the resonating is happening. The panels are not ridgid so they ring... particularly at 70hz. which is 16' wavelength and the panels are 4' in length and are only secured on each end while the entire piece floats in place. Dynamat will deaden this and should eliminate the problem but my uncle said I need to be careful since I know these panels excite at 70hz if I deaden them 100% they will absorb that frequency too much. He recommended just placing a 12"x12" square on each panel and remeasure and see where it's at then.

But beyond that what you guys think? would bass traps help me out at all? My room is a second floor room with a 2x6 tongue and groove subfloor w/ carpet. It seems the walls and floor act as a bass trap themselves and most of my waterfall in this graph drops to room noise floor (43db at measurement) by 150ms

Is 150ms bad at this low frequency?


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## bpape (Sep 14, 2006)

I would need to see another 10db down on the waterfall. In a residential sized room I tend to look at 40db down from the average level. The plot you're showing only goes 30db down.

I would put a brace from the wall/ceiling to the peak of the arc on the polys and then stuff with insulation. Stiffen them up and let them work for you instead of against you.


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## Talley (Dec 8, 2010)

bpape said:


> I would need to see another 10db down on the waterfall. In a residential sized room I tend to look at 40db down from the average level. The plot you're showing only goes 30db down.
> 
> I would put a brace from the wall/ceiling to the peak of the arc on the polys and then stuff with insulation. Stiffen them up and let them work for you instead of against you.



Thanks I'll keep those in mind. 

I can show you 40db down but the it gets into my floor noise. Mine fluctuates based on my house... the quietest my room has been is 37db but normally with the a/c running or the dishwasher going or just many other things (even the airplains overhead since we are 7 miles from the airport and landing aircraft fly over all day) with having 4 kids running around my room is not as quiet as it should be. I'll show you the graph at 40db down and it hangs out to 1.5 seconds which is my house noise. 

Next time I'll be sure to increase the volume so I get 40db above my rooms floor noise. Thanks for the tip.


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## bpape (Sep 14, 2006)

The 300ms window is really more of what you want to look at. It's showing that in fact, yes, there is still a need to tame the decay time in the low end a bit.


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## dgmartin (Oct 29, 2011)

Talley said:


> Here's why the resonating is happening. The panels are not ridgid so they ring... particularly at 70hz. which is 16' wavelength and the panels are 4' in length and are only secured on each end while the entire piece floats in place. Dynamat will deaden this and should eliminate the problem but my uncle said I need to be careful since I know these panels excite at 70hz if I deaden them 100% they will absorb that frequency too much. He recommended just placing a 12"x12" square on each panel and remeasure and see where it's at then.


Hello Talley,
Dynamat will more than likely drop the resonance frequency of your panels below 70Hz (added mass). Difficult to estimate how much not knowing thickness, materials... anyways you are better off just re-measure. Out of curiosity, what is the intended benefit of those devices?


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