Hello,
I have used 2" denim insulation in the past to line speaker boxes, but I was wondering how it compares to felt like Troels Gravesen uses.
Is 1/2" felt thick enough to absorb longer wavelengths?
This is the felt I was going to use in 1/2",
F-26 Industrial Felt By Foot
– thefeltstore.com
I was still going to use 2" denim behind the woofer and at the top and bottom of the box.
Here is what the box looks like,
I have used 2" denim insulation in the past to line speaker boxes, but I was wondering how it compares to felt like Troels Gravesen uses.
Is 1/2" felt thick enough to absorb longer wavelengths?
This is the felt I was going to use in 1/2",
F-26 Industrial Felt By Foot
– thefeltstore.com
I was still going to use 2" denim behind the woofer and at the top and bottom of the box.
Here is what the box looks like,
Attachments
WOW, gorgeous boxes. I would also put the felt/denim on at least (1)side wall as well.
If troels uses it then it must be good stuff.
Looks like that f26 is natural wool which is better than synthetic but it only has 45% natural wool content.
Check out the f10, it has min 80% natural wool.
If troels uses it then it must be good stuff.
Looks like that f26 is natural wool which is better than synthetic but it only has 45% natural wool content.
Check out the f10, it has min 80% natural wool.
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Tall skinny box, have you accounted for it being an ML-TL and not a BR?
Felt & loose each have their uses. You want natural fibres, wool or cotton, then there is a spectrum of density from felt thru to phluff. Denser will typically act at higher frequencies, you need significant volume fill for sealed and often in a TL.
We typically use 12mm denim/cotton felt near the driver to kill early reflections and then, althou we have used the denim/cotton insulation density material as volume fill, we typically use well teased acoustistuff for volume fill.
dave
Felt & loose each have their uses. You want natural fibres, wool or cotton, then there is a spectrum of density from felt thru to phluff. Denser will typically act at higher frequencies, you need significant volume fill for sealed and often in a TL.
We typically use 12mm denim/cotton felt near the driver to kill early reflections and then, althou we have used the denim/cotton insulation density material as volume fill, we typically use well teased acoustistuff for volume fill.
dave
A BR you only line the walls. An ML-TL often needs volume fill of teased polyfill/acoustastuff/long haired sheep’s wool.
dave
dave
-really beautiful wood-work there, makes me think one side should be glass or clear acrylic. 😎
What you are already using is far superior to the Industrial Felt. It's mostly down to how thick the material is, and how "lossy" for a given bandwidth. The Denim insulation at 2-4" is very broad-band, figure the 2" is decent down to 400 Hz, and the 4" to almost 200 Hz. Anything lower than that starts becoming an exercise in futility. Because the Denim insulation is as "lossy" as it is: it's excellent at high freq.s - substantially out-performing something like 2 or 4" mineral wool beyond a certain freq. (..like greater than 4 kHz).
Ideally you should NOT put the felt on the *walls, but instead SUSPEND it (OFF of the cabinet walls) within the cabinet. Doing-so lessens low-excursion losses of the driver's compliance, reaction to the BR "pipe", and the BR "pipe's" own operation.
*a potential exception to this is when the material is well away from the drivers, like in your design at the bottom of the cabinet. You can even get some lower freq. performance gains by separating the 2" layers with air-space (like stacking a sandwich, where air-space is between the layers of insulation).
Note: a thicker felt on the walls can be beneficial in the context of sound *leakage* from/(through) the cabinet walls, though you are using fairly thick real-wood panels, so the benefit would likely be very small.
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I am a bit confused how boxes normally are stuffed, to get any resonable damping of sound waves the damping material needs to be about 1/8 wavelength thick, for a one meter high floorstander without inner shelfs, to break up the total length, that means the thickness needed is about 1/4 part of the interior length. The loudspeaker box is also a resonant system and the damping material will change the resonant system Q and it can change it a lot, only few seems to work in both of these dimensions
A well designed cabinet, well braced and rigid, should have minimum wadding as possible.
I spent 2 years designing a pair of DIY speakers and wadding took a lot of testing to get right.
I used Troals dense stuff. Uses lots of energy. I couldn't stand it in my design.
Weighing poly fill to just 200g behind midwoofer to stop reflections was clearly best.
I don't like lining side walls at all. Let them sing through the side walls.
Bitumen was used on rear panels in my tests as this benefited every design I have done
Digital scales and weighing as you test gets best and balanced results in good cabinets like yours
I spent 2 years designing a pair of DIY speakers and wadding took a lot of testing to get right.
I used Troals dense stuff. Uses lots of energy. I couldn't stand it in my design.
Weighing poly fill to just 200g behind midwoofer to stop reflections was clearly best.
I don't like lining side walls at all. Let them sing through the side walls.
Bitumen was used on rear panels in my tests as this benefited every design I have done
Digital scales and weighing as you test gets best and balanced results in good cabinets like yours
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