Some relevant points here. I'd like to cover the other side of these..
Sealing the woofer chamber completely is not necessary or even wanted. As long as you don't have a problem with chuffing or whistling, a leak allows atmospheric pressure equalisation. Your example of an open backed tweeter would remain relevant to that case.
A significant portion of any woofer vibration coupling can come via the panels directly. Sealing against pressure in the cabinet is not going to do much in that respect.
It would be most excellent if there was a way to parameterize this with variables for diameter and depth.
Not sure if there's a tool to do this.
How did you design this model?
Are you able to output .stl files?
I was surprised to find that I could see light through tiny gaps in my 3D prints, you might want to spray
the interior with truck bed liner or something similar.
Not sure if there's a tool to do this.
How did you design this model?
Are you able to output .stl files?
I was surprised to find that I could see light through tiny gaps in my 3D prints, you might want to spray
the interior with truck bed liner or something similar.
I designed them in Fusion 360 which is what I use at work. A stripped down version of this is free for download on the Auto desk site. You cna learn how to use it. It's not that difficult. I taught myself in about 2 months.
I can output STL files. You would not be able to see through my prints. I have an industrial level 3d printer, not a hobbyist grade one. I print almost exclusively polycarbonate and ASA. most of my 3d printing is for aerodynamics parts on motorsports cars.
By parameterize do you mean testing different shapes and such? That would end up being quite expensive as a roll of quality ASA is $28 and even cheap PLA is $12 (couldn't use PLA because it couldn't handle the heat of a driver). Printing one these takes up an entire roll of filament. 1 kilo.
I can output STL files. You would not be able to see through my prints. I have an industrial level 3d printer, not a hobbyist grade one. I print almost exclusively polycarbonate and ASA. most of my 3d printing is for aerodynamics parts on motorsports cars.
By parameterize do you mean testing different shapes and such? That would end up being quite expensive as a roll of quality ASA is $28 and even cheap PLA is $12 (couldn't use PLA because it couldn't handle the heat of a driver). Printing one these takes up an entire roll of filament. 1 kilo.
Oh yes, you can set those parameters. You can even set it for volume and then when you reshape a dimensions it will change the others to maintain said volume.
It is engineering software. Some of the other 3d modeling programs might be a little easier to use but don't allow for such exact dimensioning. Fusion 360 also has a tensile strength/flex add on that you can use to see if your part will break until a certain load. Or, in our case, how much flex your cabinet will see under a specific load at a specific point. Very useful tool
I suggest you purchase a 3d printer that has an exnlsoure built in so you can print the heat resistant materials. Open ones cna only print pla and petg. Those materials will warp in a hot car on a sunny day. Not good for drivers.
I suggest something like the QIDI XMAX3 that has a 320mm square print volume. Most of them have a volume of only 260mm square which greatly limits what you can do with it.
It is engineering software. Some of the other 3d modeling programs might be a little easier to use but don't allow for such exact dimensioning. Fusion 360 also has a tensile strength/flex add on that you can use to see if your part will break until a certain load. Or, in our case, how much flex your cabinet will see under a specific load at a specific point. Very useful tool
I suggest you purchase a 3d printer that has an exnlsoure built in so you can print the heat resistant materials. Open ones cna only print pla and petg. Those materials will warp in a hot car on a sunny day. Not good for drivers.
I suggest something like the QIDI XMAX3 that has a 320mm square print volume. Most of them have a volume of only 260mm square which greatly limits what you can do with it.
I found Fusion 360 was the easiest CAD to use, and I’ve introduced a few people to actively designing with it. The UI was quite intuitive and the workflow functioned like MS Paint on steroids. Point, click, drag, move, zoom in, click dimension, type in constraint dimensions. All in 2 seconds by moving the mouse, not command line after command line.
They no longer support my OS though (anything prior to Win10 v.1803) and I’ve moved away from subscription based software and their dwindling feature set, which bricks without internet access.
I would spray them surface with bitmen rock guard and stuff them with standard residential insulation. I had a spreadsheet comparing the noise reduction coefficients of various materials, and for this frequency range, standard insulation was superior to polyfill or foam Comfortboard 80 is another option, but is more expensive and is better for large surfaces.
They no longer support my OS though (anything prior to Win10 v.1803) and I’ve moved away from subscription based software and their dwindling feature set, which bricks without internet access.
I would spray them surface with bitmen rock guard and stuff them with standard residential insulation. I had a spreadsheet comparing the noise reduction coefficients of various materials, and for this frequency range, standard insulation was superior to polyfill or foam Comfortboard 80 is another option, but is more expensive and is better for large surfaces.
Hello,
By foam, I intend to convey open cell poly foam, like egg crate mattress material. What you are used was likely far superior, like a multi-layer product with a mass layer.
By residential insulation, I mean the “pink panther” bags of fibreglass, or the yellow type, both used as a thermal barrier.
I’ll look for the chart, but here are a few noise absorption product and material comparisons.
https://www.bobgolds.com/AbsorptionCoefficients.htm
https://www.atsacoustics.com/page--Selecting-the-Right-Acoustic-Material--ac.html
By foam, I intend to convey open cell poly foam, like egg crate mattress material. What you are used was likely far superior, like a multi-layer product with a mass layer.
By residential insulation, I mean the “pink panther” bags of fibreglass, or the yellow type, both used as a thermal barrier.
I’ll look for the chart, but here are a few noise absorption product and material comparisons.
https://www.bobgolds.com/AbsorptionCoefficients.htm
https://www.atsacoustics.com/page--Selecting-the-Right-Acoustic-Material--ac.html
Bigger volume generally deteriorates midrange. This is an often misunderstood subject. Unless you succeed in almost perfect damping of a bigger midrange enclosure, smaller is better because of internal cavity resonances being less.
Someone else mentioned covering the outside. I will be covering the outside now with butyl sound dampener material.
I am not sure the woofer will be sealed entirely. The woofer has a phase plug. I am far from certain of this but it looks like phase plug woofer have an area between the cone and woofer where air can escape.
Very interesting data there. I will have to spend some time later to dig into this and extrapolate pertinent information.
People often try to save money on damping material and get (1) cheap mattress toppers from Walmart or Amazon (open cell foam) (2) Polyfil from Joanne's or cheap pillows, (3) pink fiberglass insulation...
If you want you splurge on quality R11 or R13 felt (3/8 to 1/2 or more inch thick) from McMaster-Carr and Merino wool (Merino wool roving or batting?) from Amazon and probably other places that I'm not aware of.
If you want you splurge on quality R11 or R13 felt (3/8 to 1/2 or more inch thick) from McMaster-Carr and Merino wool (Merino wool roving or batting?) from Amazon and probably other places that I'm not aware of.
So this is what I currently use. It is open cell and surprisingly heavy. It is underlayment for floors. I haven't tested it against anything but I feel like it works quite well. If you stick it to a board and rap your knuckle on said board it will ring out at a lower frequency.
Attachments
I have yet to read the first argument in favor of a bigger enclosure. Seems that people like ringing mid frequencies.
Use proper acoustical wadding from specialist suppliers. And no, the stuff you have probably isn’t a good absorption material. Look it up, there are resources on that everywhere. Like here
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The only study I have seen is "A Study on Midrange Enclosures" parts 1 and 2 by Jim Moriyasu in Speaker Builder 2000.
Conclusion of Part 1: None of the box shapes (cube, golden ratio rectangle, flat backed cube, three-sided pyramid and four-sided pyramid) made much of a difference. The cube should theoretically be the worse and "daggers" and "wedges" should be better, but none made a significant difference.
Conclusion of Part 2: The bigger the enclosure the better (regardless of shape) and damping is critical (regardless of size or shape). i.e., regardless of shape, small or large, undamped enclosures did poorly.
I don't necessarily accept the findings of a 24 year old article, but thought it was interesting that the only article I know of suggests bigger midrange enclosure is better.
