Acoustic treatment

Helmholtz resonators’ effective frequency is a function of volume of the bottle, the diameter of the nozzle and the length of the nozzle so even a Coke bottle can be converted into a tube trap. It’s not rocket science! 🚀 The problem arises at shows where many Coke bottles and beer bottles litter the room randomly, creating acoustic chaos. 

It is easy to Dampen frequencies 250 Hz and up. Doing so creatively can make a big improvement in imaging. Unfortunately as you go further down especially as the wavelengths get longer than 100 Hz it becomes progressively harder. I have played with tube traps in two installations with severe comb filtering and irregardless of anything I did with the traps could not get the variation below 10 db. This is walking around using a volume meter and tone generator. In both instances I told the customer that he needed a new room. Back then we did not have room control. Using a good room followed by careful positioning of the speakers and the listening position and damping primary reflections with the goal of improving imaging is the best way to deal with the problem of bass in an enclosed room. Some speakers and sub woofers are significantly easier in this regard. I have never seen tube traps work and my own opinion from my admittedly limited experience is that they are a waste of money. 

Oh and Mr Rocket science. How big would a helmholtz resonator have to be to resonate at 20 Hz? Anyone care to guess?

Size isn’t everything. I just got through explaining it. Hel-loo!