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Why are all tweeters 1 inch in diameter ?

Satefan

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Modeled in CAD software i get these off axis curves for 19mm / 25mm / 50mm / 75mm pistons, as seen 2-3 inch diameters are not a very modern performance :)..

View attachment 106571

Super-interesting. I am looking to build the exact same model for the 25mm dome, but in REW so i can use them as overlays for my own accoustic off-axis measurements. Is your graph of the 25mm 'exportable' so i could (if you are willing to share) import it in REW somehow?

Thanks,

Satefan
 

BYRTT

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Super-interesting. I am looking to build the exact same model for the 25mm dome, but in REW so i can use them as overlays for my own accoustic off-axis measurements. Is your graph of the 25mm 'exportable' so i could (if you are willing to share) import it in REW somehow?

Thanks,

Satefan

Attached in below zipfolder :) its txt-files created in free VituixCAD software so REW should be happy import those, have fun inclusive the building process..
 

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Satefan

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Modeled in CAD software i get these off axis curves for 19mm / 25mm / 50mm / 75mm pistons, as seen 2-3 inch diameters are not a very modern performance :)..

View attachment 106571
Attached in below zipfolder :) its txt-files created in free VituixCAD software so REW should be happy import those, have fun inclusive the building process..

Thanks! I also use Vituixcad, but have not found the way to build these. I need them at about 65dB or so - i'll try to figure out!
 

BYRTT

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Thanks! I also use Vituixcad, but have not found the way to build these...
Velcome, into VituixCAD go "Tools/Calculator" and use below dialogs to print out piston size txt-files one at a time..

Satefan_1.PNG

...I need them at about 65dB or so - i'll try to figure out!
Using same calculator as above VituixCAD can offset all them txt-files in one click, 1) pick or say highlight all of them as "A responses", 2) place a dot in "Real A", 3) up at the top of the window there is a dialog called dB where you write 65 to get them offset +65dB but also its possible offset the other way using a negative sign "-" in front of written numbers, 4) Guide where you want the files to be printed using "Destination directory" dialog, 5) hit "Calculate & Save" to print those offset txt-files.

To offset into REW its one at a time using below dialogs..
Satefan_2_EDIT.PNG
 
Last edited:

rdenney

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There is an old trick, beloved of, e.g., Henry Kloss -- the "cone/dome" hybrid tweeter.
...

A later post showed the Altec design that is relevant to my (very late) reaction to this statement. The fried-egg tweeter that Kloss designed for the Advent Loudspeaker was not a hybrid cone/dome. It was actually a dome with a radiating compliance. The outer part of the radiating element is not mounted in a compliance the way a dynamic cone would be. His discovery was that the outer part of the structure would radiate significant mid-range energy, so it's really more of a hybrid mid-tweeter. His contention was that the output part would not radiate significant high-frequency power, and so at high frequencies it behaved like a 1" dome tweeter.

Rick "just clarifying Kloss's claims, not validating them" Denney
 

rdenney

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This variability is coming about because the horn / waveguide is providing impedance matching between the driver and surrounding air, acoustic impedance being the ratio of pressure and velocity. A compression driver does not have too much surface area or excursion, but it can exert considerable pressure. This means a characteristic impedance that's way different from free air, which you may have noticed does not take very much pressure to move quite a bit. A waveguide transforms impedance to be more suitable to transmission, effectively increasing sensitivity. A larger one remains effective to lower frequencies, hence reducing excursion. This is most easily understood if you have an idea of how RF propagation works.
...

Another late response...

It has been postulated by several of us, based on study of both Benade and Fletcher-Rossing, that the bell of a brass instrument acts as an impedance-matching device, exactly as you describe. In particular, it attenuates poorly tuned noise and reduces impedance of lower frequencies. And it absolutely affects dispersion patterns--directivity.

So, acoustic propagation works similarly to RF propagation. Who knew?

Rick "who passed his amateur radio exams based on his understanding of acoustics in the frequency domain" Denney
 

Descartes

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Interesting tweeters on older Sonus Faber are pointy, what is the advantage to do that? I believe they were design by SEAS!
 

Satefan

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Velcome, into VituixCAD go "Tools/Calculator" and use below dialogs to print out piston size txt-files one at a time..

View attachment 128307

Using same calculator as above VituixCAD can offset all them txt-files in one click, 1) pick or say highlight all of them as "A responses", 2) place a dot in "Real A", 3) up at the top of the window there is a dialog called dB where you write 65 to get them offset +65dB but also its possible offset the other way using a negative sign "-" in front of written numbers, 4) Guide where you want the files to be printed using "Destination directory" dialog, 5) hit "Calculate & Save" to print those offset txt-files.

To offset into REW its one at a time using below dialogs..
View attachment 128311


Wonderful. I found the option to offset the graph in REW, and will look at the option VituixCad shortly. Truly appreciate your help!
 

Blaspheme

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Interesting tweeters on older Sonus Faber are pointy, what is the advantage to do that? I believe they were design by SEAS!
Sonus Faber used the ScanSpeak ring radiator tweeter in their Stradivari circa 2005. The pointy bit is a phase plug. Audio Physic used the ring radiator around that time too in their iconic Virgo (and other models) before replacing that with a cone tweeter of their own design.

Meanwhile, Yamaha are continuing to use dome midrange on their modern remake of the NS-1000 (now NS-5000, so five times time better) using novel zylon instead of beryllium.
 
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