Getting there - I have both the Behringer ECM8000 mike and also the Mini dsp one too - I need to download the program (REW?) and learn how it 'make it go' - can get assistance when restrictions lifted.
I have 'grooved' the back if the flat baffle and can bend it into a curve, with the uneven wings as per the Betsy design, so that's on the way, no problem.
I have a hot-knife with straight blade/wand so curved styrene profiles are okay too.
I have 'grooved' the back if the flat baffle and can bend it into a curve, with the uneven wings as per the Betsy design, so that's on the way, no problem.
I have a hot-knife with straight blade/wand so curved styrene profiles are okay too.
That's good 
I don't have a proper computer so can't use any of the great programs out there. I think this Ripple Tank Simulation is probably telling the truth regards the story of the nulls, or at least the bigger more general picture and for the purpose of a fullrange driver in an open baffle it's probably good enough. I presume hornsrep would be a better tool to use?
Polystyrene should be fine so long as you can give it a smooth, hard finish, although I don't know how effective it is at stopping lower frequencies.
I don't have a proper computer so can't use any of the great programs out there. I think this Ripple Tank Simulation is probably telling the truth regards the story of the nulls, or at least the bigger more general picture and for the purpose of a fullrange driver in an open baffle it's probably good enough. I presume hornsrep would be a better tool to use? Polystyrene should be fine so long as you can give it a smooth, hard finish, although I don't know how effective it is at stopping lower frequencies.
Will look into the programs a bit more - I wouldn't mind being able to measure and check the waterfall and room energy decay too for myself but this interesting project will finally get me off my 'A' and get stuck into it.
Surfacing the styrene isn't a problem - can always finish it in car repair fibreglass, heavy duty exterior paint, etc.
Surfacing the styrene isn't a problem - can always finish it in car repair fibreglass, heavy duty exterior paint, etc.
I'm no expert about any of this but I did organize a couple of different 8" drivers into spherical chambers (16" dia ceramic balls) and played around with various internal diffusion schemes (with varying success, as you can imagine!) but the common result was the dramatic improvement in the front radiating pattern of the driver and the improvement of the 'evening-out' of the freq response - one of the main aims was to also NOT compress the dynamics by over-damping - not so easy to do.
Anyhow, the idea about the curved baffle was to emulate this but with an open baffle with a similar bend to enhance the horizontal dispersion and achieve similar reduction in these 'nulls' and you and Allen have shown with the modelling that it's worth persevering with for that aspect alone - and I can do the 'hack-work' quite well, if slowly!
But, and it needs more consideration, no doubt, is the concave rear area and how that effects the front behavior plus how the rear radiating pattern behaves - with the use of diffusors, I'm not that concerned about probable nodes/nulls but as not everyone is in a position to space their speakers so far out from the wall, it would be good to see just how good/bad the rear energy behaves.
There's a Betsy thread on our familiar "AudioCircle" that describes the folded open baffle that has the 9" front face, one side panel of 18" and the other side at 8" both slanted back at 45 degrees - for full signal, the height is 4 ft but as mine are only reaching 150, or thereabouts, I 'postulated' (yeah!) that the height can be reduced to 30" without problems and probably can also reduce the sides to something towards those 14" and 2" sides of the NXOtica design.
Anyway, that was the attraction to the idea of not just the front curve but the whole torus and also that our 'guru' Earl Geddes had also thought it worth more experiments.
Computers - I'm still using my Toshiba i5 laptop upgraded with the Windows 10 program but organizing a newer unit to use just for music and without the Windows - surprisingly, the jRiver music program (with the Wasabi turned on) does mate up well with my Ayre Acoustic dac (QB-9) so I have good signal - still struggling with the SOtM server, has a mind of it's own!
Just starting on the new 6-24 analog Xover for the F6 amp for high pass signal and aiming for about 150Hz at 12dB slope - the 15" bass driver in it's 3 cu ft chamber is okay up to around 500Hz with the current internal baffles but showing some 'box noise' above that so don't want to raise the xover point much higher than ...
I just had a 'look-see' on the "Gedlee Website" and there's a notice up that he's retired now and concentrating mostly on his glass work projects so we might only see some sporadic visits.
Yes, from your shape trials, a straight face inner surface next to the driver at the 30 degrees looks most promising - much easier to do too! Thanks for that.
Anyhow, the idea about the curved baffle was to emulate this but with an open baffle with a similar bend to enhance the horizontal dispersion and achieve similar reduction in these 'nulls' and you and Allen have shown with the modelling that it's worth persevering with for that aspect alone - and I can do the 'hack-work' quite well, if slowly!
But, and it needs more consideration, no doubt, is the concave rear area and how that effects the front behavior plus how the rear radiating pattern behaves - with the use of diffusors, I'm not that concerned about probable nodes/nulls but as not everyone is in a position to space their speakers so far out from the wall, it would be good to see just how good/bad the rear energy behaves.
There's a Betsy thread on our familiar "AudioCircle" that describes the folded open baffle that has the 9" front face, one side panel of 18" and the other side at 8" both slanted back at 45 degrees - for full signal, the height is 4 ft but as mine are only reaching 150, or thereabouts, I 'postulated' (yeah!) that the height can be reduced to 30" without problems and probably can also reduce the sides to something towards those 14" and 2" sides of the NXOtica design.
Anyway, that was the attraction to the idea of not just the front curve but the whole torus and also that our 'guru' Earl Geddes had also thought it worth more experiments.
Computers - I'm still using my Toshiba i5 laptop upgraded with the Windows 10 program but organizing a newer unit to use just for music and without the Windows - surprisingly, the jRiver music program (with the Wasabi turned on) does mate up well with my Ayre Acoustic dac (QB-9) so I have good signal - still struggling with the SOtM server, has a mind of it's own!
Just starting on the new 6-24 analog Xover for the F6 amp for high pass signal and aiming for about 150Hz at 12dB slope - the 15" bass driver in it's 3 cu ft chamber is okay up to around 500Hz with the current internal baffles but showing some 'box noise' above that so don't want to raise the xover point much higher than ...
I just had a 'look-see' on the "Gedlee Website" and there's a notice up that he's retired now and concentrating mostly on his glass work projects so we might only see some sporadic visits.
Yes, from your shape trials, a straight face inner surface next to the driver at the 30 degrees looks most promising - much easier to do too! Thanks for that.
The inner radius of the torus must match the driver radius, but the outer radius is a variable, so there isn't a single value of "rounding". I expect a "bigger" torus will yield better LF loading because the dipole moment is greater. This logic can be taken to very large enclosures.
I no longer do much in audio myself. My system is as good as I have ever heard and I don't tweak it anymore. I still do some consulting in areas where my expertise is hard to find elsewhere, but that is minimal. Otherwise, I am retired and spend my time in my glass studio.Have you lost interest now?
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Thanks Earl.
This from SL "The benefits of edge rounding come into play only when the radius is greater than 1/8th wavelength." Diffraction from baffle edges
This from SL "The benefits of edge rounding come into play only when the radius is greater than 1/8th wavelength." Diffraction from baffle edges
I'm confused. I don't think I mentioned curvature. Two values define a torus - the inner radius and the outer radius - the curvature is then defined by these variables, one of which is not fixed (the outer one,) so the curvature will change with this outer radius value.
I do not agree with SL's claim - it's too simplistic. It may apply to a flat baffle, but it won't apply to a torus.
I do not agree with SL's claim - it's too simplistic. It may apply to a flat baffle, but it won't apply to a torus.
James, I found an old wheelbarrow tyre yesterday, it could make a suitable candidate for a simple mock up. Initially I was after the inner tube but the tyre could be good enough. I found pinching the inner rims together produced a "waveguide" before it rounded, and being a wheelbarrow tyre it has a good rounding, not flat at all at the periphery, and minimal tread just a few shallow ribs around the circumference .
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That sounds interesting - thanks for the suggestion - would it be possible to put up a photo?
I too looked at the tubes here but didn't think about the tyre itself - so obvious when pointed out! I will have a look around - those 4 wheel trike or maybe scooter tyres might be worth a look too …
We're still on Covid 'house restrictions' so am limited access to products but it'd be good to get organized - I've got my gear sorted for some styrene cutting, etc but the tyre idea sounds a much simple thing to try
I did pick up a local spare kit of the 6-24 electronic Xover and getting my list of bits prepared too - learning about REW and so on - slowly making progress ...
I too looked at the tubes here but didn't think about the tyre itself - so obvious when pointed out! I will have a look around - those 4 wheel trike or maybe scooter tyres might be worth a look too …
We're still on Covid 'house restrictions' so am limited access to products but it'd be good to get organized - I've got my gear sorted for some styrene cutting, etc but the tyre idea sounds a much simple thing to try
I did pick up a local spare kit of the 6-24 electronic Xover and getting my list of bits prepared too - learning about REW and so on - slowly making progress ...
I somehow keep coming back to a rather large 'donut' but unsure if my arithmetic is correct.
I'm starting with the inner diameter is to be the required 8" (for the driver, as Earl mentioned) and the outer diameter is something like 38" - on other words, the cross section of the donut ring itself is 15" in diameter so we're back towards that 'rescue buoy' size.
I'm starting with the inner diameter is to be the required 8" (for the driver, as Earl mentioned) and the outer diameter is something like 38" - on other words, the cross section of the donut ring itself is 15" in diameter so we're back towards that 'rescue buoy' size.
Before you go too far down the rabbit hole, I'm still trying to get to the bottom of what's going on, I'm not convinced, see here Did Siegfried Linkwitz miss a trick?
One thing that may be missing here is the time factor of diffractions - the time delta of occurrence. If the time is very short then the peaks and dips that we usually see go away, but that does no mean that the effects go away. They are still there in the polar response.
In fact, the entire polar response of a piston in a baffle can be shown to be equivalent to an omni point source surrounded by the disks diffraction at the disks radius due to this point source. The diffraction simply becomes the directivity.
Thanks, I think I understand, but I'm not sure. Regards a dipole, the short time delta of the diffractions at an abrupt baffle edge causes the relatively narrow, deep null, and by comparison the null is spread wider around the curve of the torus baffle due to the longer time delta, the peaks are likewise spread and thus diminished?
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I'm trying to understand what I saw in the ripple tank simulations. Whist adjusting the torus shape and "waveguide" part the resultant diffractions and interference seem to follow a clear and logical pattern, easier to comprehend in picture form
GM's post here https://www.diyaudio.com/forums/full-range/249448-torus.html#post3782258 is encouraging.
GM's post here https://www.diyaudio.com/forums/full-range/249448-torus.html#post3782258 is encouraging.
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