Full range cardioid

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#105
Jag768 said:
So, another update. Lot of work done. See attached images

Updated the bracing of my subwoofers (also made a new baffle and rear side). And smoothed the waveguides and fabricated a new faceplate for the Dayton RST-28 tweeters which fits the waveguide throat. And i made a new crossover filter for the Dayton rs270 / rst-28 combi. The 900Hz xover using LR 4th order (acoustic) slopes, turned out to be the winner.

The phase overlap was excellent, resulting in good summing. I measured distortion using a 92dBspl sine sweep @ 1m. No rising distortion for @ xover freq was apparent for the tweeter.

And most importantly, the resulting polar response shows an improved constant directivity over the previous design using the B&C DE250. The dayton RS270 narrows at a lower frequency than the Beyma 10g400, however this is overcome by the lower xover frequency (900 vs 1200hz).

Next on the to do list is re-doing the multi sub setup using multi sub optimizer. My room had some acoustic changes (new doors, change of floor type). And after that all 8 new panels (4 baffles, 4 rear sides) need a finish 🙂
Click to expand...

Hi Jag -

Amazing work. I'm also contemplating using the RST28 in a waveguide, and i'm really intrigued by your diy OS axi-symmetric WG using plaster/putty. Could you share some more details of the WG making process?

Sounds like using the RST27 without the grill is the winning combination? Could you share what is the throat diameter you used to match the tweeter? What is the throat angle in the WG?

Thanks!
 
#106
rhapsodee said:
Hi Jag -

Amazing work. I'm also contemplating using the RST28 in a waveguide, and i'm really intrigued by your diy OS axi-symmetric WG using plaster/putty. Could you share some more details of the WG making process?

Sounds like using the RST27 without the grill is the winning combination? Could you share what is the throat diameter you used to match the tweeter? What is the throat angle in the WG?

Thanks!
Click to expand...
Thank you. Here is more info on how you make a waveguide out of plaster. The throat diameter is 37mm. I use a 45degree angle for the mouth. The profile looks like this

attachment.php


Indeed without grill is the winning option. You could consider trying a 0deg exit with a small radius transition to 45 degree. I haven't tried this option for the rst28.
 

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#107
Jag768 said:
So, another update. Lot of work done. See attached images

Updated the bracing of my subwoofers (also made a new baffle and rear side). And smoothed the waveguides and fabricated a new faceplate for the Dayton RST-28 tweeters which fits the waveguide throat. And i made a new crossover filter for the Dayton rs270 / rst-28 combi. The 900Hz xover using LR 4th order (acoustic) slopes, turned out to be the winner.

The phase overlap was excellent, resulting in good summing. I measured distortion using a 92dBspl sine sweep @ 1m. No rising distortion for @ xover freq was apparent for the tweeter.

And most importantly, the resulting polar response shows an improved constant directivity over the previous design using the B&C DE250. The dayton RS270 narrows at a lower frequency than the Beyma 10g400, however this is overcome by the lower xover frequency (900 vs 1200hz).

Next on the to do list is re-doing the multi sub setup using multi sub optimizer. My room had some acoustic changes (new doors, change of floor type). And after that all 8 new panels (4 baffles, 4 rear sides) need a finish 🙂
Click to expand...

Looking good! Ziet er goed uit!
 
#113
Hello,
I am discovering your wonderful work on the development of a cardioid U-cabinet, and I would like to ask you for some clarification:
I am considering a similar realization from a 6.5 inch driver.
Is the depth of the U-baffle 20 cm?
Can you explain the Sd parameter?
Can you say more about the length of the vents, their position and their area?
Thank you in advance.
 
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