Like just perfectly said oldhvymec, thanks to his generous friendship, The Helmholtz or H. method is the way to tune a room complementarily to the passive material treatment... It is a machanical adjustable set of H. bottles and tubes of different size with different necks, mechanically adjustable at will in diameter and lenghth , which are distributed in a grid around the location of my speakers and myself in the room, at key locations , beginning at few inches from each tweeter or bass drivers and at some reflection points at right and left of my speakers and behind my position of listeming,,,
The grid created a new set of pressure zones distribution in the room where the goal is to accomodate FOR the specific speakers and to the specific ears of the owner the specific acoustical content of the room...
These locations of some resonators near at few inches of the tweeter and bass drivers are not symmetrical for each speakers, because of the first wavefront law in psycho-acousatic, who says our brain accomodate each direct front waves from each speakers differently for each ears with a time delay...The goal is to help the brain figuring out and calculating the position of the sound sources in the room...
I used it to create a better imaging then and also i used reflections time and reverberation... To use them i made listening experiments during some months each day, like a tuner tune a piano, listening instruments timbres and voices in the room to accomodate the room acoutic content characteristics to the speakers characteristic mechanically....One modification at a time....
Someone could say it is impossible to implement this in an incremental way because some modification can reverse some other positive one on the frequencies spectrum... It is relatively true but the gist and key of the art of tuning them is to adjust them not perfectly but optimally BECAUSE each of the many hundred of modifications possible COMPENSATE one another.... At the end the micro structure of the tone playing instrument and voices are natural for your SPECIFIC ears and you are able to perceive his flowing surfaces and volumes....
All is made of plumber tubes or bottles i take from my basement or from a flee market,....
By the way the H. resonators are absorbing devices but also diffusing one... i used passive materials to control but also use the reflections.... In small room reflections are NOT only negative waves to eliminate but waves you could use to reinforce imaging..... Small room acoustic is NOT great Hall acoustic....Reverberation time did not play the same role and function to the perceptive ears....
You can make the H. resonators very distributive of some frequencies range by varying the aperture of the bottles and shortening the neck....I dont made any precise calculus even if the H. method is MATHEMATICAL... Whith more than 50 H. devices they compensate each other all along the frequencies range all along the tuning process, if i used the TIMBRE perception like a meter ruler in my listening experiments...
The human ear is trained by millions years to perceive human voice....The human ears is NOT trained naturally to perceive one frequency of very thin set of frequencies like a microphone in an electrionical process of equalization...My H. grid is a MECHANICAL equalizer and the ears replace the test microphone, and the timbre large spectrum replace the test frequency used in electronical equalization...It is better because the grid is part of the room, the sweet spot is distributed in INCHES not in millimeters like in electronical equalization...
It takes a dedicated room, it is impossibble to do this in a living room...
The only cost is the time it takes .... Few months each day because i am retired...
Peanuts costs...
Then with the passive acoustic treatment and the active H. mechanical one, if you take care of vibrations in the system, and if you decrease the electrical noise floor of the house you make what i call the three main working embeddings dimensions control of any audio system, then, your system is not the better there is for sure but so much good and relatively optimally well controlled than UPGRADING will make you smile...
There is a limit to optimal Sound quality / price ratio...
All that seems complicated but it is not , it take much time , reading, but NO COST...
Acoustic is the sleeping queen, all the pieces of gear are only the 7 working dwarves....
what is the Helmholtz method?
