Hej Elleman
Nice! I might do something similar...
Did you do any test? How do they sound?
I am curious about materials you used in proto, also what materials you will use for end product, any stuffing?
Is it important the seal between panel and walls? What did you used?
About the panel material , maybe using a more flexible panel, if you cut it wider on top you can get more volume and more parabolic shape
Imagine the foam core board, like in the thread
http://www.diyaudio.com/forums/full-range/223313-foam-core-board-speaker-enclosures.html
For low power applications works fine, the sealing on the edges might be quite good being foam, and if you cut some horizontal lines, so material can be curved, you can get a bigger and bigger opening
Modelling in hornresp would be a different story, challenging at least...
Also the sides of the panel must be cut with curved shape (not as easy), but can be obtained from 3d modelling software
Example with some sections cut horizontally, bending each section outwards 2º from the previous one (vs straight triangular panel)
But angle could also be increased as approaching to the end
And once fixed to the wall with some tension, panel might be sturdy enough
mRRk
Nice! I might do something similar...
Did you do any test? How do they sound?
I am curious about materials you used in proto, also what materials you will use for end product, any stuffing?
Is it important the seal between panel and walls? What did you used?
About the panel material , maybe using a more flexible panel, if you cut it wider on top you can get more volume and more parabolic shape
Imagine the foam core board, like in the thread
http://www.diyaudio.com/forums/full-range/223313-foam-core-board-speaker-enclosures.html
For low power applications works fine, the sealing on the edges might be quite good being foam, and if you cut some horizontal lines, so material can be curved, you can get a bigger and bigger opening
Modelling in hornresp would be a different story, challenging at least...
Also the sides of the panel must be cut with curved shape (not as easy), but can be obtained from 3d modelling software
Example with some sections cut horizontally, bending each section outwards 2º from the previous one (vs straight triangular panel)
But angle could also be increased as approaching to the end
And once fixed to the wall with some tension, panel might be sturdy enough
mRRk
They sound alright and fits the purpose perfectly since the music is just there. Not really a point origin so to speak.
I built these ones from two shelves i had laying around which were 295X1800mm so the dimensioning was accommodated to fit that, as seen in the hornresp simulation i posted earlier. I have some stuffing below the speaker as well as a little bit shoved in just above it and this helped the characteristics a bit.
I had some self adhesive foam strips that i attached to the chamfer of the board that then got mushed together in the mounting. As you can see from the picture of the first prototype vs the 2, i have added more screws. the board did vibrate a bit too much and i had to secure it more to make it rigid and seal to the wall. I would suggest to glue them for the permanent mounting. I would also warn about that the panels themselves becomes a bit of a resonance surface if they panel are a bit flimsy, but as handled in the Foam core speaker thread, this might not be as big of an issue. Could also be that if i use a proper plywood material it would behave allot better than this shitty shelf material.
since it's such a simple "build" i would suggest to experiment! of course the wall will take a hit but if it's going to end up something there eventually, just go for it!
I built these ones from two shelves i had laying around which were 295X1800mm so the dimensioning was accommodated to fit that, as seen in the hornresp simulation i posted earlier. I have some stuffing below the speaker as well as a little bit shoved in just above it and this helped the characteristics a bit.
I had some self adhesive foam strips that i attached to the chamfer of the board that then got mushed together in the mounting. As you can see from the picture of the first prototype vs the 2, i have added more screws. the board did vibrate a bit too much and i had to secure it more to make it rigid and seal to the wall. I would suggest to glue them for the permanent mounting. I would also warn about that the panels themselves becomes a bit of a resonance surface if they panel are a bit flimsy, but as handled in the Foam core speaker thread, this might not be as big of an issue. Could also be that if i use a proper plywood material it would behave allot better than this shitty shelf material.
since it's such a simple "build" i would suggest to experiment! of course the wall will take a hit but if it's going to end up something there eventually, just go for it!
i would have gone with this idea so as to raise the driver from being at bellybutton height.
and i'd make them red to match the curtains!
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i like the curtains and Christmas but after this past winter the snow can't melt fast enough for my liking!!
if angled down slightly having them higher would mean them being heard through out the kitchen...kitchen parties are the best, never have to go far for the next round and food's close.
if angled down slightly having them higher would mean them being heard through out the kitchen...kitchen parties are the best, never have to go far for the next round and food's close.
To comment on my own comment.
To be honest I am a bit disappointed at the lack of depth for the size. Earlier in the thread i made a smaller bib of the 3fe25 which i would say performed on a similar level if not better.
The peak around 120hz seems to be due to the room and not really possible tame in a good way.
If i compare to the same drivers in my 3d printed egg speakers the response looks like this before and after EQ at a distance of about 1 meter (the listening position since it is for the PC). the resonance peak at approx 120 hz here is a mix of the tuning frequency of the boxes, the corner/room position etc. But here i could fairly easy compensate with an EQ, as the green line is the actual measurement and not calculated. I guess it is due to the direct sound instead of the bibs relaying on the room which makes them more difficult to tame..
I will measure these outside when i get the chance to see their actual response.
What do you get if you roll up a BiB instead of folding it? Something that looks like a fossil ammonite shell. I wrote a program to create the spiral given the line length and mouth dimensions from the BiB spreadsheet. The back is heavy-duty corrugated cardboard. The front is 3mm door skin plywood. The spiral is made of corrugated packing roll that is like corrugated cardboard but has flat paper backing on just one side. It rolls easily. The central part of the spiral is a single layer, and the outer is two layers. The edge of the spiral is glued to the cardboard back with carpenter's glue. I worked in sections and used a large wooden cutting board with weights to clamp while the glue dried.
The driver is the MarkAudio Alpair 7.3 is a 4 inch class driver. There isn't room for the usual driver placement of LL x 0.217. Instead, I used the LL x 0.561 position (found elsewhere in this thread). I clamped the front baffle on temporarily with threaded rods and nuts at the outermost dots. I'll need to borrow some clamps to close some gaps for testing and when I glue on the front.
How does it sound? I think it sounds better than it has any right to, considering the humble materials. The Alpair needs breaking in, and I haven't added any stuffing. The rough corrugations on the outside of the curve and the convex smooth surface do a good job of breaking up internal reflections. I suppose the regular 8mm spacing of the ribs could create a resonance at 43 kHz and its subharmonics. Any thoughts on this? My plan is to add light stuffing on each side of the driver and dense stuffing near the center of the spiral. With no stuffing, the mid and high frequency response sounds very clear, better than my every-day speakers. The bass is not loud, but considering the driver's Fs = 75 Hz, it might be all I can get.
The driver location is intriguing. When I tap on the back along the midpoint of the last turn of the spiral, I get a sudden change in pitch of the resulting "thunk" as I pass the midpoint of the driver over the span of an inch.. As z increases near the driver location, the pitch suddenly drops an octave as I pass the driver location.
I think this is a reasonable approach for a 3" or 4" driver, but it won't scale up very much with these materials. If one sounds good, I may make a second one and hang them on the wall of my great room.
The driver is the MarkAudio Alpair 7.3 is a 4 inch class driver. There isn't room for the usual driver placement of LL x 0.217. Instead, I used the LL x 0.561 position (found elsewhere in this thread). I clamped the front baffle on temporarily with threaded rods and nuts at the outermost dots. I'll need to borrow some clamps to close some gaps for testing and when I glue on the front.
How does it sound? I think it sounds better than it has any right to, considering the humble materials. The Alpair needs breaking in, and I haven't added any stuffing. The rough corrugations on the outside of the curve and the convex smooth surface do a good job of breaking up internal reflections. I suppose the regular 8mm spacing of the ribs could create a resonance at 43 kHz and its subharmonics. Any thoughts on this? My plan is to add light stuffing on each side of the driver and dense stuffing near the center of the spiral. With no stuffing, the mid and high frequency response sounds very clear, better than my every-day speakers. The bass is not loud, but considering the driver's Fs = 75 Hz, it might be all I can get.
The driver location is intriguing. When I tap on the back along the midpoint of the last turn of the spiral, I get a sudden change in pitch of the resulting "thunk" as I pass the midpoint of the driver over the span of an inch.. As z increases near the driver location, the pitch suddenly drops an octave as I pass the driver location.
I think this is a reasonable approach for a 3" or 4" driver, but it won't scale up very much with these materials. If one sounds good, I may make a second one and hang them on the wall of my great room.
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You could use the same techniques found in the foam-core cornucopia thread. Looks to be simialr in size to the smaller version, but much deeper.
dave
dave
Dave,
I think the Cornu Spiral is about the same depth because it's two 3 inch layers with a partition in between, so 6.1 vs 6.25 inches deep. It would be interesting to compare them. The thought of cutting through one layer of foam board 200 times to bend it into a spiral is enough to discourage me from trying the BiB spiral foam board build. This rolled corrugated single face cardboard sure was easy to work with, and it stiffens nicely with a coat of Titebond 2 glue.
Robert
I think the Cornu Spiral is about the same depth because it's two 3 inch layers with a partition in between, so 6.1 vs 6.25 inches deep. It would be interesting to compare them. The thought of cutting through one layer of foam board 200 times to bend it into a spiral is enough to discourage me from trying the BiB spiral foam board build. This rolled corrugated single face cardboard sure was easy to work with, and it stiffens nicely with a coat of Titebond 2 glue.
Robert
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The original is, the smaller copies are not as thick. There was a subwoofer made which is much larger.
dave