Ohm Walsh F Hope of Resurrection

pch300, that is a terrific idea (if one wishes to bypass), to go direct to the inputs on the driver struts! Superb! That will be my game plan, should the speaker's renovation come out ok. Excellent, and beneficial advice! Personally, this has been among the most practically� beneficial threads I have benefitted from on Agon.  :) 

In preparation for the reconditioning of the spiders and surrounds of the Ohm Walsh F, I removed the assembly to discover VERY stuffed cabinets! Wow, talk about jammed to the gills with what appears to be a mesh sack full of foam chunks! My first thought is, "Well, that would deaden a speaker pretty quickly!" 

I'm planning on removing this sack of debris and conducting tests with other materials. I presume that if the cabinet is left sparse, the sound signature will change radically, and likely for the worse. I wonder, however, if the mid to high frequency response will improve if a mountain of foam is not literally semi-blocking the drivers. 

As I'm thinking this through, I suspect the reason the bass bin was jammed so full was to force the sound to emanate from the driver versus emptying into the cabinet, and I also suspect the delayed propagation of the wave into the cabinet might be pretty ugly sounding. But, who knows until tried? 

I would think that a different foam might confer a nice improvement to the speaker's sound. I think I'm going to start with an empty cabinet beneath to assess the range of effects. 

Has anyone else experimented with that aspect of the speaker? 

The Ohm F is a acoustic suspension speaker system, which means the cabinet is a sealed box. Because of the sealed cabinet and no crossovers, the system should roll off at 12 dB/octave below the cutoff frequency. I think the foam stuffing so full in the box is there for a specific purpose. You'd have to ask Ohm whether the stuffing is there for the purpose I think is.

In an acoustic suspension speaker box design, lining the internal cabinet walls with absorptive material is one method used to damp the sound wave reflections inside, reducing standing waves. Stuffing the box loosely-full will change the thermodynamics inside the box as well. This makes the box act as if it were bigger than its actual physical internal dimensions. That lowers the resonant frequency, so extends the bass when using a smaller cabinet volume that otherwise would have been bigger. There is a tradeoff with this - lower efficiency, for example. If I remember, this affects the system Q (resonant peak width) too, through damping.

The stiffness of the surround and spider along with the moving mass (plus damping) contributes to defining the resonant frequency of the driver. That in conjunction with the cabinet size and stuffing determines the system resonant frequency in the bass, among other things. Any changes you make to the surround or spider stiffness will affect these things. 

I suspect that in the Ohm F, the internal stuffing plays another role, that of absorbing the acoustic wave emitted by the inside surfaces of the cone. Otherwise, the internal reflections will interfere with the later sound waves travelling down the cone.

Pch300, yup, parallel thoughts here.  :)
I'll just have to experiment,  and of course keep the original stuffing in case I need to revert to it. However,  as with many things in audio, I have found that a decent design may be improved. Emphasis on "may", as no one knows unless tried. That's how I came up with the Schroeder Method of IC Placement.   I'm guessing it will be really ugly without any damping,  but I want to explore the spectrum  because I suspect an even better result is attainable.  

Should be an interesting project.