hi all
have a look at my fotoblog with the idea of a fully hornloaded, state of the art hornspeaker :
http://www.flickr.com/photos/7808268@N07/?saved=1
Angelo
have a look at my fotoblog with the idea of a fully hornloaded, state of the art hornspeaker :
http://www.flickr.com/photos/7808268@N07/?saved=1
Angelo
Re: its thin plywood 5mm
http://www.flickr.com/photos/7808268@N07/465154478/
It's typically best to avoid spacing braces equally as that divides the panel into sections which will each resonate at the same frequency. Also, you're doing the same kind of thing vertically, you should at least have two different brace shapes and alternate them so as not to create vertical sections of the enclosure with the same consistant width as you go from the bottom to the top as that will also cause it to resonate at paticular frequencies. Since you are laminating to build the cabinet anyway, why not take advantage of the benefit of laminating different materials (specifically, materials with differen't "Q's? It can make a significant difference damping cabinet vibrations.
Edit: if the cabinet will only be playing at low frequencies, then those resonaces may not be excited so significantly, so what I said above is not quite so applicable when talking about subwoofer cabinets, for instance. Still, something to keep in mind, generally.
After looking at this:angeloitacare said:hi
i use thin, 5mm plywoodlayers, glue 3 of them at the time together with apropriated glue. I do not know in the u.s. the brandnames, i guess any store that sales the plywood can inform u.
rds Angelo
http://www.flickr.com/photos/7808268@N07/465154478/
It's typically best to avoid spacing braces equally as that divides the panel into sections which will each resonate at the same frequency. Also, you're doing the same kind of thing vertically, you should at least have two different brace shapes and alternate them so as not to create vertical sections of the enclosure with the same consistant width as you go from the bottom to the top as that will also cause it to resonate at paticular frequencies. Since you are laminating to build the cabinet anyway, why not take advantage of the benefit of laminating different materials (specifically, materials with differen't "Q's? It can make a significant difference damping cabinet vibrations.
Edit: if the cabinet will only be playing at low frequencies, then those resonaces may not be excited so significantly, so what I said above is not quite so applicable when talking about subwoofer cabinets, for instance. Still, something to keep in mind, generally.
Those look great Angelo. Can't wait to see them completed. The Bossa Nova has a way cool shape. WIll you build one?
The photo's gave me a laugh. Brown skin and flip-flops on the feet (we call them "slippers" here in Hawaii). Looks just like a Hawaiian workshop!
Tropical Audiophiles unite!
The photo's gave me a laugh. Brown skin and flip-flops on the feet (we call them "slippers" here in Hawaii). Looks just like a Hawaiian workshop!
Tropical Audiophiles unite!
Re: enclosure resonances
A layer of metal, or even beter, two layers of two different metals - or - a "constrained damping layer" of some viscous sticky sheet such as something with bitumen, or "loaded" vinyl sheet with adhesive in between the wood layers...
Alternate bracing distances, yes. A thin layer of MDF won't that much difference, I think, as it is not very dense, not very strong, and only somewhat different Q than plywood.angeloitacare said:hi Critofur
the last layer of the cabinet will not be plywood, but mdf, witch will make it easier to work with the wood veneer afterwards. If i understand it right, you recommend to alterate the bracing distances one to the other ?
rds Angelo
A layer of metal, or even beter, two layers of two different metals - or - a "constrained damping layer" of some viscous sticky sheet such as something with bitumen, or "loaded" vinyl sheet with adhesive in between the wood layers...
hi Critofur
the distances are not exactly the same, they vary one from the other, it is not very mutch, so it cannot be seen on the pictures. I dont think i will find bitumen or something similar here around. Resonaces should be already at a good degrea avoided with this bracing, don't you think?
rds Angelo
the distances are not exactly the same, they vary one from the other, it is not very mutch, so it cannot be seen on the pictures. I dont think i will find bitumen or something similar here around. Resonaces should be already at a good degrea avoided with this bracing, don't you think?
rds Angelo
Well, what frequency range will that portion of the speaker play in?
The bracing does look intelligently designed, and should be decent.
Test the speaker and place a microphone very close ( a few mm away) from the center of the space between braces and see if you detect a resonant peak in the cabinet.
Play the speaker with frequency sweeps at a fairly loud level and see if you feel resonances activated at certain frequencies.
If you will be playing at low frequencies then you may want to add a solid wood brace or two. The woofer will be mounted on the front?
It looks good, but you might find something needs improvement after you test it. On one speaker cabinet I designed it was surprising to find that 1/2 inch plywood was noticably superior to 3/4 inch plywood. Somehow the thicker plywood had worse resonances in that particular design.
The curved surface will help a lot, it's so much stiffer than the sides of a rectangular box, did you have that in mind when you designed it? Perhaps it is just a lucky side effect of your asthetic choice?
The bracing does look intelligently designed, and should be decent.
Test the speaker and place a microphone very close ( a few mm away) from the center of the space between braces and see if you detect a resonant peak in the cabinet.
Play the speaker with frequency sweeps at a fairly loud level and see if you feel resonances activated at certain frequencies.
If you will be playing at low frequencies then you may want to add a solid wood brace or two. The woofer will be mounted on the front?
It looks good, but you might find something needs improvement after you test it. On one speaker cabinet I designed it was surprising to find that 1/2 inch plywood was noticably superior to 3/4 inch plywood. Somehow the thicker plywood had worse resonances in that particular design.
The curved surface will help a lot, it's so much stiffer than the sides of a rectangular box, did you have that in mind when you designed it? Perhaps it is just a lucky side effect of your asthetic choice?
the woofer will be crossed at 220hz
hi Critofur
the bass will be crossed at 220hz 12db ore 24db. Yes, the woofer will be mounted on the front, also a rectangular port, 30cm deep. the walls are 30mm ( more than 1inch ) thick. To get good aesthetics was my main goal, beside to do it right to avoid resonances.
rds angelo
hi Critofur
the bass will be crossed at 220hz 12db ore 24db. Yes, the woofer will be mounted on the front, also a rectangular port, 30cm deep. the walls are 30mm ( more than 1inch ) thick. To get good aesthetics was my main goal, beside to do it right to avoid resonances.
rds angelo
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