And maybe why they seem to only use it in HT speakers. Their high end all seem to be conventional ported.
This thread is originally about reporting experiments concerning the effect of stuffing on sealed box Fs and Q. The consensus seems to be that reducing both is a good thing. I definitely got the impression from the OP poster that under his conditions it was impossible to stuff sufficient material to attain an optimum Fs and Q. (except in possibly one case). However later posters have repeated the common claim that there is an optimum stuffing density beyond which the Fs will start to rise. Is there a reference for studies that show this effect?
In a slightly different direction, what are the subjective effects of an overstuffed box compared to an "optimum" stuffing density? It would be great if someone has compared two identical complete sealed speaker designs except with different stuffing densities. Actual experience please, not theoretical speculation.
In a slightly different direction, what are the subjective effects of an overstuffed box compared to an "optimum" stuffing density? It would be great if someone has compared two identical complete sealed speaker designs except with different stuffing densities. Actual experience please, not theoretical speculation.
Yes, some materials you can stuff tight enough that you go past optimum, whatever your optimum is. Optimum being totally a choice in the design.
It should be somewhat intuitive you are not going to make a driver do more than it can do by basic calculation. Stuffing is "cheating" the properties of the air in the box.
At some point, it should be obvious, the stuffing becomes more solid than matrix. With much time and some money, a more competencies approach, graphing/predicting densities and how they relate to the basic driver parameters would be fun. I can think of many possible variables I don't have time to play with. Any students out there in need of a paper? Size of pores, length of fibers, resonance of fibers, surface texture of fibers, mass of fibers, bonded or not, cross section ratio, stuffing properties to volume etc.
I only went far enough to dispel a lot of advertising hype on miracle fibers and at least in my test AC and the micro pore idea. My sealed subs seem to work best with plain old pink insulation fiber glass, and my ported satellites seem to be a toss up between wool and bonded Daycron. When I get around to it, I still want to order a roll of mineral wool insulation as I can always use the extra in my attic. On maximum densities, only was the cotton bat not springy enough to let me actually grandiosely over-stuff. I found "pretty tight" to be about right. Much denser that I would have guessed. I did not try compressing open cell foam, nor did I have easy access to foam with different pore sizes. (I would love to have a chunk of memory foam to see what it does)
I feel your frustration that instead of getting others to pick up on ideas and do some testing themselves, it seems to have had more of a prod to emphatic arguing about personal beliefs or blind believing advertising.
Right now, I have to complete several furniture projects so I don't know when I can get back to my next project: a thin wall mounted sub and a higher polish paint job on my living room mains.
Every project teaches something. One big lesson is how much more patient I need to be in my paint jobs. Instead of hours and days between coats and buffing, it needs to be weeks, and instead of 3 or 4 coats, it is more like a dozen. I understand better why a friend who used to do auto restorations would have his customers come back 6 months later for a final buff. ( tells you something about those 4 day TV show restorations )
I have learned in the last year:
How important the front baffle radius is
How much denser the stuffing needs to be
Better at balancing BSC, position, and crossover points to smooth the response.
I have not perfected paint jobs on MDF. I have not done much with veneer and want to compare my best MDF boxes with top grade ply.
I provided this link before and will again here
Content warning
pls disregard the content warning. You are not being linked to a porn site. I think the WWW has interpreted the title of John's derivation incorrectly because it's entitled "Aural Fixation". I'm sure meant tongue and cheek; not knowing the content warning would be applied by the WWW poice.
The derivation worked out here by John O'Hanlon provides the theoretical means to explain why FG works better than PET. His example is for a simple 2 dimensional model. The math is beyond me, but I'm sure a 3 dimansional extension of John's work would be even more accurate in predicting stuffing performance.
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Make sure you use quite a few of them- I did this in my Canvas build with decent results. I used a spray-adhesive and applied by hand.
Later,
Wolf
cotton balls are a great budget stuffing. I havent seen that bamboo fibre before, that could indeed be interesting to try out.
I learnt on my 1st build just how much work spray painting an MDF box was. Before i tried sealing with household emulsion I laid down probably half a dozen primer coats, same or slightly fewer for colour coat, and the same for lacquer. I found i had to wait 2 weeks at least before re-lacquering otherwise i removed far more than overspray. Tedious and it turned out ok, but not the piano gloss id hoped for.
A luthier friend recommended a 2 part setting lacquer he uses. I cant recall the brand, but it certainly wasnt cheap. However it worked a treat when he re-lacquered my faithful ol' geetar, with a brush no less.
I learnt on my 1st build just how much work spray painting an MDF box was. Before i tried sealing with household emulsion I laid down probably half a dozen primer coats, same or slightly fewer for colour coat, and the same for lacquer. I found i had to wait 2 weeks at least before re-lacquering otherwise i removed far more than overspray. Tedious and it turned out ok, but not the piano gloss id hoped for.
A luthier friend recommended a 2 part setting lacquer he uses. I cant recall the brand, but it certainly wasnt cheap. However it worked a treat when he re-lacquered my faithful ol' geetar, with a brush no less.
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