Tvrgeek,
I am talking about a larger cone in a small enclosure, not a small device in a small enclosure. So being able to simulate the larger enclosure is interesting for that reason. I am building the driver so I can change any parameter in the device like increasing cone mass or changing the suspension compliance. I have free reign on the design of the device but am limited in what would be acceptable in a desktop speaker size even a larger model. And I do plan on using electronics to supplement the response curve.
I am talking about a larger cone in a small enclosure, not a small device in a small enclosure. So being able to simulate the larger enclosure is interesting for that reason. I am building the driver so I can change any parameter in the device like increasing cone mass or changing the suspension compliance. I have free reign on the design of the device but am limited in what would be acceptable in a desktop speaker size even a larger model. And I do plan on using electronics to supplement the response curve.
I'm in the process of revamping a pair of old speakers that have both undersized boxes and inadequate damping ( 2" of FG along the backwall).
It's an uber-compact system, with a 15" woofer in a small 1.5 cuft sealed box
The results from an online calculator (using WT3 data from the free woofer, and a preferred .707 Qtc) called for a 3.0 cuft sealed box, without stuffing.
Speaker Box Calculations
Since I'll be re-using the boxes (Qtc .98), a Qtc of .707 will be difficult if not impossible.
So far, to deaden some resonances, I've lined the sides and backwall with some self-adhesive vinyl roof flashing.
http://www.diyaudio.com/forums/multi-way/215133-box-colourations-really-31.html#post3095327
I've also cut some 3/4" slices of memory foam (from an old Tempurpedic pillow, using an electric kitchen knife) which I plan on stapling to the the top and bottom, and maybe to the backwall behind the woofer
http://www.diyaudio.com/forums/full...-differences-poly-fill-types.html#post2581375.
For increasing the apparent volume and lowering the Qtc, I've ordered some BL cotton, which I'll test and report back on here. I really don't want to use FG if I can help it, but in this situation I might just have to if the cotton is insufficient.
It's an uber-compact system, with a 15" woofer in a small 1.5 cuft sealed box
The results from an online calculator (using WT3 data from the free woofer, and a preferred .707 Qtc) called for a 3.0 cuft sealed box, without stuffing.
Speaker Box Calculations
Since I'll be re-using the boxes (Qtc .98), a Qtc of .707 will be difficult if not impossible.
So far, to deaden some resonances, I've lined the sides and backwall with some self-adhesive vinyl roof flashing.
http://www.diyaudio.com/forums/multi-way/215133-box-colourations-really-31.html#post3095327
I've also cut some 3/4" slices of memory foam (from an old Tempurpedic pillow, using an electric kitchen knife) which I plan on stapling to the the top and bottom, and maybe to the backwall behind the woofer
http://www.diyaudio.com/forums/full...-differences-poly-fill-types.html#post2581375.
For increasing the apparent volume and lowering the Qtc, I've ordered some BL cotton, which I'll test and report back on here. I really don't want to use FG if I can help it, but in this situation I might just have to if the cotton is insufficient.
sba;
You might want to consider an aperiodic enclosure type for your loudspeaker. It can be useful if your goal is to lower the effective Qtc of the system.
Aperiodic Loudspeaker Enclosure Design
You might want to consider an aperiodic enclosure type for your loudspeaker. It can be useful if your goal is to lower the effective Qtc of the system.
Aperiodic Loudspeaker Enclosure Design
Actually, I live in a 1961 Levitt and Sons which came with all of 2" rock wool. Its buried in the attic under a foot of new FG. Just not going there. I don't see any need. We established about a 10% increase if Fs. I figure that is about done unless those who argue with my method but have not done any testing themselves actually step up to the plate. Now to look at damping reflections. Anecdotal comments suggest it should be a good run between cotton and wool. I am going to have to set this up in a quieter environment than my office. Or, I could just use the wool and acoustastuff I bought.
Tvrgeek,
I was being tongue in cheek on that rock wool comment. I don't think I would want to dig through 1 foot of fiberglass myself. And I worked in fiberglass shop when I was much younger. Not nice stuff to play with....... Still okay if I need to laminate a cheap composite part, but that is about all I want to do with that stuff these days.
I was being tongue in cheek on that rock wool comment. I don't think I would want to dig through 1 foot of fiberglass myself. And I worked in fiberglass shop when I was much younger. Not nice stuff to play with....... Still okay if I need to laminate a cheap composite part, but that is about all I want to do with that stuff these days.
My brother recently filled a pair of Heresy 3 cabinets with the high density yellow fiberglass found in the white vinyl clad 2'x4' ceiling tiles. the material in these was about 1/2" thick. With just under three tiles in each cabinet they are very full and they work extremely well. They cost about $6.00 a piece (2'x4'). easy to use and place fairly clean for a glass product.
Kapock which is a short fiber cotton material can be purchased from upholstery shops. I have had extreemly fine results with perlite but it must be contained. Best regards Moray James.
Kapock which is a short fiber cotton material can be purchased from upholstery shops. I have had extreemly fine results with perlite but it must be contained. Best regards Moray James.
10%
I just had dinner with my attorneys and they said I should never settle for small amounts. Didn't your test result in an undersized box going from Qtc 1.11 down to 0.77 via the use of FG ? WTF, my attorneys might be contacting you
hi d10... ,
Yes that's one of my goals.
I've seen those scan speak vents before, and I definitely need to check into this. Thanks for bringing this to my attention.
Philips used to fill their 70s and 80s vintage sealed enclosures with this material. (About 2/3 the volume of the enclosures.) These were the speakers with one or two AD8066 woofers, an AD5060 midrange, and an AD0140 or AD0160 tweeter.
Okay all you geniuses here. If we are to use the gas filled bag method rather than just filling a sealed enclosure, what type of bags do we use and how do we attach them? Or do we just have the bag or bags float freely in the interior of the enclosure? Couldn't the bag itself if left free resonant against the sides of an enclosure and make their own noise?
Steven
Steven
No bags(They will nullify the effects of the gas and will actually raise the resonant frequency of the enclosure by displacing the "available" air in it), just seal the cabinet completely. Since the gas is 5 times heavier than air, barometric pressure is irrelevant(Won't be able to push the cone inward or outward much). The gas is also made up of extremely large molecules, so they(molecules) won't be able to escape over time like a gas similar to helium. Just don't move to a much higher or lower elevation after sealing them.
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Remlab,
I just thought that this is what I had read earlier when I looked at one of the references sighted earlier, that they had recommended the bag method for loudspeakers. Now if you are going to use the gas in a commercially produced product what do you do about shipping and not knowing where the product could end up. What if the enclosure is used in Denver or some low elevations how could you compensate for the pressure changes or final outside ambient pressure?
Steven
I just thought that this is what I had read earlier when I looked at one of the references sighted earlier, that they had recommended the bag method for loudspeakers. Now if you are going to use the gas in a commercially produced product what do you do about shipping and not knowing where the product could end up. What if the enclosure is used in Denver or some low elevations how could you compensate for the pressure changes or final outside ambient pressure?
Steven
That is the problem with this approach. It can only be used successfully in a diy (Stay in one place) type application. Imagine putting bags of this gas in your lungs and expecting your voice to go lower when you talk. All it would do is take up valuable lung air space. It would be nothing more than a gimmick if it were to be placed in bags..
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