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Best damping stuff for fullrange
Best damping stuff for fullrange
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Old 11th September 2016, 05:24 AM   #11
naca5 is offline naca5  Belgium
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Thanks both,
I remember that Pencils need around 700gr. Once teased is this not too much?
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Old 11th September 2016, 08:43 PM   #12
killmister is offline killmister  France
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Aquarium woolfilter. Cheap and efficient. The advantage is its low density. Used successfully in bibs and bass reflex. The second advantage is that it tears easily but it is still strong enough for a loudspeaker. It's very easy to adjust stuff quantity with it.
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Old 11th September 2016, 10:01 PM   #13
Scottmoose is offline Scottmoose  United Kingdom
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Depends on what is meant by 'too much.' I spec. Dacron as a catch-all generic for hollow-fill polyester fibre which is generally the easiest type of material for people to obtain throughout the world. The quantities are a nominal only. The point of the pensil alignment (or at least one of them) is that it is relatively easy to adjust to requirements based on room acoustics, amplifier output impedance and personal taste. Hence the removable back. Not all Dacron is created equal -there are many different types, just as there are many types of damping materials, and they all possess somewhat different properties, so this is something for you to experiment with. Using the nominal quantities, you will have a quasi-TL impedance; it's more or less a flat-line unreactive load. But leaving aside variations in material, most people don't like having that much damping in the cabinet. Keep it a little way from the driver or you may mass-load the cone / suspension, preventing them from oscillating / resonating as designed.
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Old 12th September 2016, 06:36 AM   #14
naca5 is offline naca5  Belgium
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Quote:
Originally Posted by Scottmoose View Post
Depends on what is meant by 'too much.' I spec. Dacron as a catch-all generic for hollow-fill polyester fibre which is generally the easiest type of material for people to obtain throughout the world. The quantities are a nominal only. The point of the pensil alignment (or at least one of them) is that it is relatively easy to adjust to requirements based on room acoustics, amplifier output impedance and personal taste. Hence the removable back. Not all Dacron is created equal -there are many different types, just as there are many types of damping materials, and they all possess somewhat different properties, so this is something for you to experiment with. Using the nominal quantities, you will have a quasi-TL impedance; it's more or less a flat-line unreactive load. But leaving aside variations in material, most people don't like having that much damping in the cabinet. Keep it a little way from the driver or you may mass-load the cone / suspension, preventing them from oscillating / resonating as designed.

Thanks for that, hopefully my backs are removable.
Will experiment polyester fiber.
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Old 12th September 2016, 07:03 AM   #15
robskillz is offline robskillz  Europe
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Does anyone use Sonofil from Intertechnik?
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Old 22nd September 2016, 09:50 AM   #16
bhpistorqintorpm is offline bhpistorqintorpm  India
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hi friends,
i'm planning to build this simple BR enclosure for Alpair 10M [design from frugalphile.com]

http://p10hifi.net/FAL/downloads/CGR...lan-040414.pdf

planning to use following damping material for lining the cabinet walls:

DAC - Polyfill Speaker Cabinet Sound Damping - 450 GSM Sheet

does this still need Recron kind of filler for the box?
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Old 22nd September 2016, 05:48 PM   #17
planet10 is offline planet10  Canada
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Best damping stuff for fullrange
That damping looks fine.

Quote:
does this still need Recron kind of filler for the box?
???

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Old 24th September 2016, 01:04 PM   #18
Gaga is offline Gaga  Europe
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Best damping stuff for fullrange
Quote:
Alpair 10.3 in Pencil
Betsy K in Baronet

I'm wondering which damping stuff will be better and if there better one for BLH and Pencil desgn.
Well, strongly depends on type of enclosure, i.e. closed, BR, BLH, TML, which frequencies to damp or if you intend to enhance the virtual volume of an enclosure etc.

Measurement of relative damping at different wavelength can be found here (check the thread for measurement setup and details).

Damping material consisting of non-rigid fibers will transform movement of gas-molecules into heat and tend to act on all wavelength, more rigid dampening material (like Basotect, porous foam) will preferably act on higher frequencies (shorter wavelength).

Thus, for closed enclosures, choice of damping material is not that critical and I'd use e.g. something like polyester fibers, Dacron, and so on.

For BR-enclosures I'd go with Basotect (actually a mixture of Basotect and Fibsorb turned out to best from my experience / measurements), as you selectively want to dampen standing waves in the enclosure, but not bass frequencies (see figure given in the link above).

Please note, that the amount and packing density of fibre material can have a huge impact on damping characteristics: As soon as packing density of fibre material increases (i.e. less degree of freedom to move for the fibers) the more selectively damping can be achieved. Again see linked figure, compare 'Twaron locker' = Twaron lightly stuffed and 'Twaron extra' = compressed Twaron. Same happened with Fibsorb or Polyester fibers. See as well post by planet10 on teased/non-teased poly-fill.

Now, damping of a TML or BLH (back-loaded horn I suppose?) is special and tricky. You want to dampen the standing wave, which is relatively close to the bass frequencies you want to amplify without dampening bass response. That's why dampening instruction of TMLs and BLHs are usually very specific with respect to type, amount and placement of damping material...

In general, placement of damping material plays a crucial role as well, if you do not stuff the entire enclosure (e.g. midrange enclosure), as damping i most effective at the place where you have fastest movement of gas molecules (i.e. away from the wall, just between the two walls producing the standing wave).

Hope that helps.
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Old 24th September 2016, 04:42 PM   #19
naca5 is offline naca5  Belgium
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Thanks Gaga, very helpfull..
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Old 26th September 2016, 08:29 AM   #20
theaudiopath is offline theaudiopath  Australia
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Where tone is critical I go for 50/50 wool / dacron,pollyfill pillows @ $16 au average each @ Dymocks our Aussie haberdashery . I'm sure you would have a similar equivalent in your vicinity. Would prefer 100% wool as I think it sounds the best but the above can usually had for 1/3 the price. An acceptable compromise. I know it sounds better but I wish someone could tell me why? Just remembered Visaton that German DIY loudspeaker manufacturer sells long fibre wool damping.

Last edited by theaudiopath; 26th September 2016 at 08:43 AM.
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