I too was thinking that the waveguide would over power edge diffraction somewhere above 2.5kHz or so..
I was thinking somewhere above 300Hz where for the mid to take over from the twin woofers and somewhere above 2.5kHz where the tweeter takes over from mid.. This is just speculation right now as I have not finalised any plans...
The factory data sheet shows these details for this coax:
Tweeter polars:
Woofer polars:
I too don't know much about this coaxial driver at the moment. My inspiration to use this driver is from fluid's posts in other threads about SICA coaxes (he mentions about the 6.5 inch version of this coax, I think) and projects like these:
http://www.donhighend.de/?page_id=7291
One of the things/issues i do want to hear and understand is acoustical intermodulation that Kimmosto has mentioned about coaxes in the past.
I too am interested in the waveguided compression driver vs coax comparison. I don't know if this particular coax can ever keep up with the CD+horn combo, but as you said, if I succeed in putting this coax in a good enclosure, it would definitely be any interesting comparison and learning for me too.. Also the horn that I currently have will change to something better, hopefully soon.. . In fact the comparison between different horns itself will be very interesting for me as I am already hearing the "best I have ever heard" type of sound now and discovering details that I have missed/never properly heard in music tracks in the past..
Tweeter polars:
Woofer polars:
I too don't know much about this coaxial driver at the moment. My inspiration to use this driver is from fluid's posts in other threads about SICA coaxes (he mentions about the 6.5 inch version of this coax, I think) and projects like these:
http://www.donhighend.de/?page_id=7291
One of the things/issues i do want to hear and understand is acoustical intermodulation that Kimmosto has mentioned about coaxes in the past.
I too am interested in the waveguided compression driver vs coax comparison. I don't know if this particular coax can ever keep up with the CD+horn combo, but as you said, if I succeed in putting this coax in a good enclosure, it would definitely be any interesting comparison and learning for me too..
Also the horn that I currently have will change to something better, hopefully soon.. . In fact the comparison between different horns itself will be very interesting for me as I am already hearing the "best I have ever heard" type of sound now and discovering details that I have missed/never properly heard in music tracks in the past..
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exactly right@augerpro:
My current enclosure front is looking like this:
View attachment 1070491
In the final enclosure, I want the driver recessed into the face of the enclosure with the a 6mm ish roundover/chamfer starting where driver frame ends. Inspiration is fluid's sims from the past for wesayso's line array enclosure build..
This roundover/chamfer is supposed to merge into the enclosure body here in my case.
Are you saying that the blue colored circled part I have marked in above pic is too abrupt a transition and it is better to have a smoother bigger rounded transition there?
Something like this?
View attachment 1070495
Matching the curvature and then gently adjusting it will give a smooth response. There is very little "edge" diffraction to worry about with the coax, you can see it's not a problem in KEF's sharp edged boxes. There can be quite a change to the look of the overall diffraction response by guiding the wave all the way around.
In this case the edge radius doesn't have the same effect, it is not the sole termination of the profile as it is on a flat baffle rectangular box.
I've attached a crossover example LR4 2.5K based on some data sent to me by @airvoid of some Sica 5" coax measurements. You can see that overall the Sica is pretty good and up there in overall design strategy with the KEF units but without some of the refinements.
The off axis peak at 1500Hz from making the on axis flat is a good example of something that won't sound right and some compromise between on and off axis will be needed. This was a flat test baffle and some of the features would be different in different enclosures.
Attachments
One piece of advice I feel confident in giving after having talked to driver designers, measured and listened to cd and dome based coaxes in prototype boxes, is to pretty much forget about on axis performance and concentrate on power/ DI and off axis performance.
Best use imo is a pair of speakers parallel against the front wall (placed c/c 2m when listening at 3m f.i. would be at 20 degrees), in other words @10-20 degrees these devices degrees tend to perform and measure better.
Best use imo is a pair of speakers parallel against the front wall (placed c/c 2m when listening at 3m f.i. would be at 20 degrees), in other words @10-20 degrees these devices degrees tend to perform and measure better.
Absolutely agree, every coax looks much better in the 10 to 20 degree range just like a decent waveguide does.
Okay so while I wait for my coaxes to arrive, I am thinking and working on my System-3
This is a traditional 2 way speaker with a shaped baffle and waveguided tweeter. I want the cabinet shape to look like below:
I don't mind the color of the drivers and the waveguide...
What I want is that overall similar cabinet shape but with my elliptical waveguides designed by augerpro.
Again, the bass and upto 350ish Hz will be handled by my Satori woofers in a 3 way configuration.
So these are the drivers I have available:
On the Left is SB15CAC, Middle tweeter is SB26CDC to be mounted on elliptical waveguide (printed in SLS nylon in the past. The color has faded and sort of yellowed), and on the right is Wavecor WF120BD03.
I am almost torn between the two mid drivers thinking about which one to use.
Here is how their normalized polars shown on hificompass website looks like:
Polars for SB15NBAC:
Polars for Wavecor WF120BD03:
Here is the upto 90degree measurements I captured with the tweeter waveguide combination (on my foam box chamfered baffle box), again with a 150uF capacitor in series with driver (this was captured at a time when I was learning to take measurements, so could be wrong also to some extent.. ):
I like the looks of polars better for the wavecor (it is also a really really cute little driver and looks very well built) but power handling and distortion may also need to be considered before I pair up the drivers. Here is where I am a little confused.
Which one should I go for driver choice-wise?
Due to the constraints in the place and situation I live in, I cant do much woodworking myself. I am really tired asking around for help from people here in India regarding building the cabinets I design. many of my plans are modified as per their wishes.
When I say I want 1inch roundover, they say it doesn't matter much. we will do a 1/4th inch roundover. When I say I want a chamfer, they say, it wont affect and we have really nice speakers with no roundover/chamfer. Those who know proper woodworking here don't care about speaker building projects. CNC guys are the worst.. They just don't care about the whole thing. Not even interesting in cutting an MDF sheet into rectangular pieces.
Due to all this, I am going to keep this two way build smaller (but not to the extent of introducing a lot of compromises acoustically).
So if everything else fails I am going to 3D print the baffles myself. And try to assemble a small enclosure to put it along with the drivers..
Thanks
Vineeth
This is a traditional 2 way speaker with a shaped baffle and waveguided tweeter. I want the cabinet shape to look like below:
I don't mind the color of the drivers and the waveguide...
What I want is that overall similar cabinet shape but with my elliptical waveguides designed by augerpro.
Again, the bass and upto 350ish Hz will be handled by my Satori woofers in a 3 way configuration.
So these are the drivers I have available:
On the Left is SB15CAC, Middle tweeter is SB26CDC to be mounted on elliptical waveguide (printed in SLS nylon in the past. The color has faded and sort of yellowed), and on the right is Wavecor WF120BD03.
I am almost torn between the two mid drivers thinking about which one to use.
Here is how their normalized polars shown on hificompass website looks like:
Polars for SB15NBAC:
Polars for Wavecor WF120BD03:
Here is the upto 90degree measurements I captured with the tweeter waveguide combination (on my foam box chamfered baffle box), again with a 150uF capacitor in series with driver (this was captured at a time when I was learning to take measurements, so could be wrong also to some extent..
):I like the looks of polars better for the wavecor (it is also a really really cute little driver and looks very well built) but power handling and distortion may also need to be considered before I pair up the drivers. Here is where I am a little confused.
Which one should I go for driver choice-wise?
Due to the constraints in the place and situation I live in, I cant do much woodworking myself. I am really tired asking around for help from people here in India regarding building the cabinets I design. many of my plans are modified as per their wishes.
When I say I want 1inch roundover, they say it doesn't matter much. we will do a 1/4th inch roundover. When I say I want a chamfer, they say, it wont affect and we have really nice speakers with no roundover/chamfer. Those who know proper woodworking here don't care about speaker building projects. CNC guys are the worst..
They just don't care about the whole thing. Not even interesting in cutting an MDF sheet into rectangular pieces.Due to all this, I am going to keep this two way build smaller (but not to the extent of introducing a lot of compromises acoustically).
So if everything else fails I am going to 3D print the baffles myself.
And try to assemble a small enclosure to put it along with the drivers.. Thanks
Vineeth
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When I say I want 1inch roundover, they say it doesn't matter much. we will do a 1/4th inch roundover. When I say I want a chamfer, they say, it wont affect and we have really nice speakers with no roundover/chamfer. Those who know proper woodworking here don't care about speaker building projects. CNC guys are the worst..
Thanks
Vineeth
You need a very understanding cabinet maker. Or a very under$tanding cabinet maker.
Unless one proposes to place an order of 100(0) pieces… ala IKEA… it is very hard to get it just the way you want.
I can get cabinets for a complete kitchen makeover quicker for than a pair of custom loudspeaker cabinets.
Now we know why High end loudspeakers with complex cabinets cost at least 4 figures in £/€/$
Well at that rate may as well go all out with fancy veneers or paints for finishing.
Exactly the same situation here. I can get a complete modular kitchen/furniture done within a few days here with whatever complex geometries involved. But still nobody is interested in making a pair of loudspeaker cabinets the way I want it..
I have some back up plans like 3D printing the baffle/a shell of the complete box itself etc, given that these are boxes/enclosure shapes with maximum 25-30cm height and similar depths (even as 2 parts if required) that I am planning for this mid-tweeter cabinet. Then fill the shell with something. The motivation is from seeing projects like this:
http://www.donhighend.de/?page_id=9167
A complete 2 way speaker cabinet 3D printed and looking nice... Cabinet walls are filled with dental cement..
Over at ATH thread, people discuss about filling a horn shell with casting polyurethane etc.
I don't know the complexities involved but it seems like really nice idea..
Maybe the wall filling itself or separate material can be used to mass-load and damp the cabinet if needed.. I am thinking along these lines..
Regards
Vineeth
Very clever and nice looking cabinet.
I helped a friend which owned a 'fonderie d'art' ( art dedicated foundry) from time to time.
To make perfect copy he used the 'lost wax' ( 'cire perdue'): i often did the first mold ( matrix) which take the imprint of the item to copy.
For this he used a kind of silicone ( two part) which is the same material used by orthodontist to mould teeth. It's relatively heavy and dependending on the amount of catalyst used will give a very 'jelly like' result. Not difficult to use or prepare if you follow instructions ( temp, weight of catalyst), it's safe for health ( no fumes or other nastys i know of).
The only bothering thing that could be needed is a vaccum pump if you insist on having no bubbles within the material ( created when you stir up the 2 parts).
Could be diy though...
Since i'm into those loudspeaker things i often though about using this material for damping.
Another 'crazy' idea i had when seeing him working was to make a mold of enclosure and use aluminium ( he worked mainly with Bronze, Silver but had alu too) to make a 2 part shell, 'a la Genelec'.
https://images.app.goo.gl/DDRv6XCRpRZJkM5E6
https://images.app.goo.gl/RDzkKYzpKfoe1HmW6
He told me this was technically possible from his side, the issue was to have the initial shell done. With 3d printing it open things...
Even a Cabasse 'Sphere' could be envisioned...
I helped a friend which owned a 'fonderie d'art' ( art dedicated foundry) from time to time.
To make perfect copy he used the 'lost wax' ( 'cire perdue'): i often did the first mold ( matrix) which take the imprint of the item to copy.
For this he used a kind of silicone ( two part) which is the same material used by orthodontist to mould teeth. It's relatively heavy and dependending on the amount of catalyst used will give a very 'jelly like' result. Not difficult to use or prepare if you follow instructions ( temp, weight of catalyst), it's safe for health ( no fumes or other nastys i know of).
The only bothering thing that could be needed is a vaccum pump if you insist on having no bubbles within the material ( created when you stir up the 2 parts).
Could be diy though...
Since i'm into those loudspeaker things i often though about using this material for damping.
Another 'crazy' idea i had when seeing him working was to make a mold of enclosure and use aluminium ( he worked mainly with Bronze, Silver but had alu too) to make a 2 part shell, 'a la Genelec'.
https://images.app.goo.gl/DDRv6XCRpRZJkM5E6
https://images.app.goo.gl/RDzkKYzpKfoe1HmW6
He told me this was technically possible from his side, the issue was to have the initial shell done. With 3d printing it open things...
Even a Cabasse 'Sphere' could be envisioned...
So I 3D printed my first waveguide.
It is the ATH generated ST260 KVAR with 1inch throat. This was a real learning experience in 3D printing even though i would have probably wasted about 250+ gm of PLA+ filament material.
I started with the regular ST260. Fluid had given me the STL files that he had designed. I tried to print it but my printer screwed it up due to the longer print times involved due to power failure related issues in my area, support failures during printing, wrong infill settings, etc. Here is what I salvaged from the whole set of disasters. Probably a close to half of the waveguide. If this had completed properly, I would have had a much better looking and feeling waveguide than what i currently have.
Dejected by the failures, I first bought a UPS for my 3D printer, then to learn this entire thing about how to assemble a waveguide printed in parts, I decided to print the KVAR version of ST260 in 5 parts. 4 petals + 1 throat piece.
Surprisingly, I was able to print the parts and assemble it together. Again each part was a learning experience in 3D printing. Hemce the petal looks and finishing varies across the different parts..
Here are some pics of what i currently have.
So the thing is assembled and glued with cyanoacrilate glue. If i hold it against the light, i can see minute gaps through the glued portions between thr petals. Is there a way in which i can fill it up? Will these minute leaks have some effect on the overall radiation pattern of the device?
All parts are printed with 15% gyroid infill. I wanted to fill up the petals but i didn't do it this time since i have to first find out what is the better available material for filling the printed parts.
Anyway, due to the lack of local availability of other compression drivers that i wanted, like the 1inch SB audience Bianco-44CD-PK, for the time being i have bought a Peerless by Tymphany DFM 2544R00 compression driver to pair up with this horn and try to take some measurements.. and listen to the overall sound of it...
It is the ATH generated ST260 KVAR with 1inch throat. This was a real learning experience in 3D printing even though i would have probably wasted about 250+ gm of PLA+ filament material.
I started with the regular ST260. Fluid had given me the STL files that he had designed. I tried to print it but my printer screwed it up due to the longer print times involved due to power failure related issues in my area, support failures during printing, wrong infill settings, etc. Here is what I salvaged from the whole set of disasters. Probably a close to half of the waveguide. If this had completed properly, I would have had a much better looking and feeling waveguide than what i currently have.
Dejected by the failures, I first bought a UPS for my 3D printer, then to learn this entire thing about how to assemble a waveguide printed in parts, I decided to print the KVAR version of ST260 in 5 parts. 4 petals + 1 throat piece.
Surprisingly, I was able to print the parts and assemble it together. Again each part was a learning experience in 3D printing. Hemce the petal looks and finishing varies across the different parts..
Here are some pics of what i currently have.
So the thing is assembled and glued with cyanoacrilate glue. If i hold it against the light, i can see minute gaps through the glued portions between thr petals. Is there a way in which i can fill it up? Will these minute leaks have some effect on the overall radiation pattern of the device?
All parts are printed with 15% gyroid infill. I wanted to fill up the petals but i didn't do it this time since i have to first find out what is the better available material for filling the printed parts.
Anyway, due to the lack of local availability of other compression drivers that i wanted, like the 1inch SB audience Bianco-44CD-PK, for the time being i have bought a Peerless by Tymphany DFM 2544R00 compression driver to pair up with this horn and try to take some measurements..
and listen to the overall sound of it... 
I think about it this way: the wavelength of 20 kHz is 17 mm, and thus 1/4 wavelength is 4.3 mm. Any gap or bump which is less than 4.3 mm will be insignificant.
Really cool waveguide, BTW...
j.