Helmhotz resonators for audiophile at almost no cost and without calculus...


The importance to treat the room if you have speakers, even in nearfield listening like me, is imperative ...

Here is my advice: 

Buy some big  empty wine bottles, or drink them before, it is optional....Or use some carafes, the kind that some display at the center of a table....I use plastic  wrapping sheets to tightly seal the aperture of the bottles and the carafes after pouring in them around 10 % of water in their volume space...You must listen and experiment for your taste and room to determine the exact amount of water to boost the frequencies that will benefit….After that  I peirce the plastic sheet with a needle and I insert a  thin straw with only the extremity of the straw at the top...  That its! You know have an Helhmotz resonator... 

You now have one of the more astounding tweak for a room that will transform your listening space in sound heaven ...I use more than 15 of them in my little audio room and trust me that is one of a kind upgrading...

I wrote that for those who want to experiment, the others can stay silent...My best to all...
128x128mahgister
As some have suggested, could you post a picture of one of your actual resonators? Especially of the straw inserted, and how far into the plastic you have it inserted? You posted that you have "only the extremity of the straw at the top", and I am not sure what you mean by that. Thanks for your help and suggestions!
Simple if you experiment just a little... 2 inches max,  out of the nozzle...The straw  is only put trough the pierced plastic sheet paper wrap used in kitchen...I put elastic to tight it around the nozzle...No need of photo for that... And I cannot put photos here even if I wanted to...I apologize for that.... I will be here to answer your question...My best to you...
Placement is very important but simple... it takes me only few try and test to discover the best or almost best...The imaging can degrade or improve  with the placement of  only one of my 2 jerrycan...
After reading your room dimensions, I can now see where you can use that many with good effect. My ceiling is only 8' (in a basement). The room itself is not ideal at 15 X15. You are correct, it's been already treated with panels, acoustic disks, etc. At this point I'm just trying to tweak it by eliminating a smidgen of the "bloom" (it's not excessive) to get more detail. I'm making some progress with a smaller opening on the resonator. 
I am happy for your progress I wish you the best and I am here to discuss if you needed to...