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Haralanov,

Here some raw cements of my on it, without any particular order of importance….

1)      Sand damping it beautiful, it is well-recognized, but you do pay cost for it, in your case the cost is space. Sand is very little compressible damping and if you have the same volume with no sand then you would have  the resonance of the whole enclosure a few dB lower, or you would have almost twice smaller enclosure for the same bass. It is important to understand that when I say “the same bass” I mean the bass in term of SPL pleasure per power. However it is very much not complete or even overlay important characteristics as it has no indication about the quality of bass that is much more complex category.

2)      Would the positive results you report be different if you have hermetic wood made compartments filed with sand without using the fabrics to hold the sand? Sure, the fabric walls is good as it has “some” elasticity but I do not think that the 25W/8565-00 driver might in this volume develop the pressure to be able to stress the fabrics-shaped sand walls.

3)      You need to take under consideration the not only the sand walls were beneficial but the face that you have the internal cavities of irregular shape – very good for Sound. Kharma Exquisite used the same idea of the internal irregular cavities…

4)      I wonder if the effectiveness of your dumping will change with time.  In a few months, when the sand in your enclosure will be settled, try to flip the enclosure upside down and see if the un-compressed, disturbed sand will have a new effect to sound.

5)      If you feel that 25W/8565-00 is a good driver then try many of 25W/8565-00. I have single driver enclosure, 2-drivers enclosure, 4-drivers enclosure  and 6-drivers enclosure . If I have space I would have 20 of the 25W/8565-00 drivers enclosure. More drivers- mean less exertions of each driver and – oh boy ! they do sound phenomenally with little power… You might try it using both channels on one side and playing mono recordings…

6)      The  25W/8565-00 are superbly sensitive to damping by amp, and a fraction of Ohm here and there do make a lot of difference.

7)      Why do you feel that the front baffle shall be as wide as possible? Where and how you cross them?

8)      Did you try to use a regular pressed wood board as you use but to pile up a 75 pounds bag of sand atop?

9)      What driver over 10kHz you use with this LF section?

10)   Do you know that you might not feel some of the compartments to the full capacity and to to shape sound in own way? You might try to bare into the sand some plastic air bubbles from packing material…. If you feel that you are too crazy then I need to disappoint you saying that I know people who pressurize the enclosure and pump inside of the box a replenishable inert gas…

11)   I see you put some kind of condom atop of the driver basket. What is it?

12)   Try to put a foam wrapper around the center poll of your enclosure.

13)   What is your feeling before and after the sane when you scratch the surface of the driver with your nail (my favorite test). The scratching the driver surface it like playing cello – by listening the harmonics of that “scratch” one can say a LOT about the bass quality…

14)   Are you planning to drive this thing with SET? Be advised that I never was able to find a SS PP amp that was able to do proper bass….

The Cat

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