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In the Forum: Horn-Loaded Speakers
In the Thread: Macondo’s Midbass Project – the grown up time.
Post Subject: The new Back chamber and the back-wiping compression driver.Posted by Romy the Cat on: 8/31/2010
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 haralanov wrote:
Also instead of using electrical tape, try to seal the back of the driver with a 2mm thick sheet of microperforated tonewood and then glue a leather layer over it. Then you could also pierce multiple tiny holes in the leather until you get the same 42Hz tunning. I think you will get much more interesting tone if you use this method.

Come on, Haralanov, of cause the electrical tape to seal the back was a temporary method just to test the needed volume. Now, sine I know what my approximate final value will be (in this case the “approximate final” is not oxymoronic) the final back chamber will will be built. It will be very massive, if you look at 3 pictures above then you will see the 3 steps of ¾ plywood – that will be the thickness of the walls with a massive sealed door on the back. The residual volume inside will be displaced. I still contemplating how. In my upperbass I used non-condensable construction foam (do not confuse with furniture of acoustic foam). I might use this method here as well but still have other options opened.
 
 haralanov wrote:
I think the degree of tonal density will jump to even higher level if you attach a thick felt on the back side of the Vitavox chassis just behind its cone. It will cost you almost no efforts to try it.

Hm, I would say rather no then yes. I have written about it in the past. I have experimented with many drivers placing in the back chambers all imaginable materials, including the felts. The result was not to straight forward. The size of the back chamber s in MF compression driver is very small, the double distance is not compatible with the wavelength, so the reflections are not truly affective in there. I do admit the with some drivers some changed were notable, including the Viotavoxes but I was not able to say certainly that one way was better then other. It was years back and I do not remember but I think even now my S2 drive that I use for MF have a very fine layer of 3M Scotch-Brite pads installed in back chambers. I think my S2 are long due to prophylactic tune up and what I do it I will confirm it. Still, I do remember that it was kind of irrelevant to me to leave the pads in the driver or to remove it after I finished my experiments as the result was not “better and worse” but rather about the irrelevant differences. I do remember that the differenced had nothing to do with tone but were rela to ability of the driver to play compressed sound in more relaxed way.

Rgs, Romy the Cat
 

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