Thanks Than! The donations really do make this possible. I don't know how many rolls of filament I've bought for this project, but it's ALOT. And a couple tweeters.
Coming soon:
There is maybe something to do with the Swans-Hivi RT2 planar serie. One is wave-guided but I dunno if it can be improved. Around 100 bucks, that makes it less expensive than the ATS2500 for instance seen In the Jim Holtz's Bordeaux.
Seems to be possible to cross-over them around 2K hz which reduce a little the c to c with a mid. VS most of the ribbons.
Can be dissassembled for another Wave Guide : http://www.troelsgravesen.dk/SWANS_RT2H-A.htm#Measurements.
Though I see guys like J Holtz or C Campbell appreciated the Fountek Neo 3 ribbon too. But haven't heard any of those three but the Hivi is said to be non fatiguing... Dunno how it competes against the Be domes. Of course the patern of a dome is easier, but many just listen to music in their chair, so maybe indeed planars should indeed not be excluded
Here are the results for the AST2560. Good start I think. The tweeter is open back, so even though my baffle is about 1m x 1.5m, you can see some dipole behavior, especially as turn the baffle off axis. I think the area below 3khz where responses are crisscrossing is due to the dipole effect. I'll be developing a back chamber for future tests. I've made one before for a speaker I did, so I have a good idea of what works well. One plot is with the faceplate attached, and the other without the faceplate. Responses were surprisingly close between the two.
It is for sure a step beyond the Founteks and Swans...
Cool, it's the vertical plot that could be interresting... the no WG seems more interresting if no further EQ in this horizontal off axis ?
Cool, it's the vertical plot that could be interresting... the no WG seems more interresting if no further EQ in this horizontal off axis ?
Now that I have a contour that is working with soft domes, I pulled out my SB29SDAC to see how it performs:
I made a vB and vC for the TW29TX and TW29RN. The difference was the curvature of the primary flare was a little less and a little more than vA posted above. For both vB was a step back, and vC was basically the same as vA. So I think vA has the best curvature. Next tests will investigate the the throat flare. This will have a big impact I'm guessing.
Similar story on the vB and vC for the Scanpseak 6640 and 6600. vB is worse, and vC is almost the same as vA. So next steps are looking at the throat flare here also.
I made a vB and vC for the TW29TX and TW29RN. The difference was the curvature of the primary flare was a little less and a little more than vA posted above. For both vB was a step back, and vC was basically the same as vA. So I think vA has the best curvature. Next tests will investigate the the throat flare. This will have a big impact I'm guessing.
Similar story on the vB and vC for the Scanpseak 6640 and 6600. vB is worse, and vC is almost the same as vA. So next steps are looking at the throat flare here also.
Just curious if you are getting close to releasing your design for the TW29TX? I'm about to start a build with mine and will probably go ahead without the waveguide for now, but if you are getting close I might wait. But going to do a removable baffle anyway so not that big of a deal to do again in the future--and then I can compare which might be interesting. Thanks for all you do!
Use a small screwdriver or Allen wrench to gently pry around the edge. It will come loose. Beware the power of the magnet pulling the tool into the dome when you do this. It's really powerful. Likewise, when you've detached the grid, pull it straight up. If you allow it to twist in your grip, the magnet will pull it right into the dome.
I like the vA already, but I want to investigate that throat curvature.
Very interested about the use of a waveguide on my TW29RN !Dug out my Satori TW29RN to see how it looks on my current contours
Hi augerpro,
I read your website with great interest, especially the part devoted to the box construction. And a question came to mind : do you know exactly what type/brand of mdf you used? and more precisely its density (kg/m3)? (this also applies to other types of panels...). This is very important in order to be able to reproduce your experience exhaustively but also to question it (because the density of the materials is more important in this case than the type of materials...).
So if you don't know the density of your materials, please, just take 1cm3 of each one and weigh it on a precision scale ! it will be much more informative.
(also be careful, panels in 1/4, 1/2, 3/4, etc. of the same range/brand do not necessarily have the same density... in general thin panels are denser than thicker ones, But everything still depends on the brand/material. So this is a very important point. To validate your experience, you need exhaustive data and benchmarks.)
I read your website with great interest, especially the part devoted to the box construction. And a question came to mind : do you know exactly what type/brand of mdf you used? and more precisely its density (kg/m3)? (this also applies to other types of panels...). This is very important in order to be able to reproduce your experience exhaustively but also to question it (because the density of the materials is more important in this case than the type of materials...).
So if you don't know the density of your materials, please, just take 1cm3 of each one and weigh it on a precision scale ! it will be much more informative.
(also be careful, panels in 1/4, 1/2, 3/4, etc. of the same range/brand do not necessarily have the same density... in general thin panels are denser than thicker ones, But everything still depends on the brand/material. So this is a very important point. To validate your experience, you need exhaustive data and benchmarks.)
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It's MDF from Home Depot, so it's nothing special. Resin content doesn't seem very high.
But I think the bigger insight from my testing is that any of the typical wood products measure similarly. If you want something better, you have to change methods (CLD) or material to something other than wood. So differences between woods is pretty meaningless. Of course I'm talking MDF and common plywoods, and I'm sure there is some random solid wood that is different enough to be marginally interesting, but that is just not a practical search when changing the method or material to something else is so much more meaningful to improving performance.
But I think the bigger insight from my testing is that any of the typical wood products measure similarly. If you want something better, you have to change methods (CLD) or material to something other than wood. So differences between woods is pretty meaningless. Of course I'm talking MDF and common plywoods, and I'm sure there is some random solid wood that is different enough to be marginally interesting, but that is just not a practical search when changing the method or material to something else is so much more meaningful to improving performance.
I promised to quickly develop waveguides for the tweeters that were just loaned to me, so haven't been able to do any more work on that. I'll be back on it soon though!
Maybe if you only see slight variations it may also be that the density of the panels you use is very close. There are several types of mdf (home depot can have only one and again the density of a 1/4 or 3/4 panel can be different in the same range, same brand): there is light mdf at 400-550 kg/m3 and heavy mdf at 700-850 kg/m3 (sometimes more). The difference between the two is huge. Same for plywood where a poplar plywood is almost 2 times less dense than a birch plywood...
Anyway, you see where I'm coming from. If your 3/4 mdf is as dense as your 3/4 plywood, you are only comparing the structural difference of the material. But if you compare a 550kg/m3 mdf and a 750kg/m3 mdf or plywood of the same thickness, you bring new data.
So I completely understand your point of view but knowing the density will bring more data to your experiences.
Personally, I don't think this is negligible, especially for something that only takes a few minutes to make.
(only to weigh a few pieces of scrap giving their precise dimensions... so it will be easy to deduce their density.)
LeRouge: "The difference between the two is huge"
It seems huge until you take a wider view and realize concrete is 2400 kg/m3 and aluminum is 2700 kg/m3. That's the point I'm trying to make. The difference between different woods is not that large in the big picture. And so neither are their resulting panel resonances. You need a fundamental change in material to make a fundamental change in resonance. You're focusing on differences that are simply not significant. If you think they may be, my method is pretty well explained at my website, you can start testing yourself. We should have more than just one source doing these things, for repeatability's sake.
Anyway, this thread is about waveguides, so this discussion should move over to my construction thread.
It seems huge until you take a wider view and realize concrete is 2400 kg/m3 and aluminum is 2700 kg/m3. That's the point I'm trying to make. The difference between different woods is not that large in the big picture. And so neither are their resulting panel resonances. You need a fundamental change in material to make a fundamental change in resonance. You're focusing on differences that are simply not significant. If you think they may be, my method is pretty well explained at my website, you can start testing yourself. We should have more than just one source doing these things, for repeatability's sake.
Anyway, this thread is about waveguides, so this discussion should move over to my construction thread.
density number is not usefull without the damping one (internal losses) ; stifness also can be reached without always increasing density. It is a layout trade off. One has to look a little more around Young modulus that works or proceed by try & error indeed with tests.
I think I postet this already somewhere ... material comparisons of sound dampening over frequency.
You need the stiffness of the material and the weight to roughly determine the behaviour. With the Chipboard there is going on some additional stuff, that's pretty rare. 40mm wood is compareable, small differences come from different stiffness (MPX vs MDF).
12mm Acryl glass has about the same weight as 20mm wood - but is less stiff -> coincidence frequency is higher. 2 Layers of 10 and 12mm Plexi would be a pretty good sandwich.
You need the stiffness of the material and the weight to roughly determine the behaviour. With the Chipboard there is going on some additional stuff, that's pretty rare. 40mm wood is compareable, small differences come from different stiffness (MPX vs MDF).
12mm Acryl glass has about the same weight as 20mm wood - but is less stiff -> coincidence frequency is higher. 2 Layers of 10 and 12mm Plexi would be a pretty good sandwich.
Here is the thread augerpro is directing you to....
https://www.diyaudio.com/community/threads/a-monster-construction-methods-shootout-thread.356130/