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Get familiar with the reaction system: Introducing the Reaction System

ND28F Ring-Radiator conversion progress...

From a sketch/alteration of a photograph:


I acquired a couple centers from my in-laws a couple weeks ago, and just now had time to have some fun with them. Due to the way they are made, they taper to a larger radius from the 3 tips to the tri-wing 'face'. I chucked the Dremel abrasive cutting wheel in the drill press to get the uniform leg dimension of 6mm longer than the tri-wing thickness. Once I got them cut down, it's apparent that this is a PERFECT FIT, and just had to be created. This set the tri-wing apex at about 3mm above the apex of the dome. I then removed the assembly screws in the ND28F-6 and counterbored the holes to insert them further. There is a stopping point inside, so they can only be driven in to a certain point, and makes them equal. Now the apexes were about 1.5mm apart. I thought this was good enough to proceed with the central anchoring dimple-point. I used the cutoff legs for the central anchor by drilling a hole in the center of the tri-wing. Arbitrarily, I inserted and set the tip length to 2mm proud of the 'wing, and it yielded a small ripple in the dome's surface of about 0.25". I played with the dome to see how it responded further, and it does start to deflect from round at a considerable distance further than that point. Being the standard 1mm Xmax guess, I felt this was appropriate.

Some more photos:



Test fit:


Clamped for glue curing:


And finally:


Testing to come...
Wolf
6thplanetsquamishdroc

Comments

  • Apparently one of the units has an intermittent connection. I'll need to get one of my other units out and convert it as well, but the impedance of the good unit shows nothing untoward. I just ripped the anchor off the second one and will use it again.


  • Interesting - what's the desired outcome of the mod? Will it lower the Fs at all? Your tweeters must be from older stock? I have a pair I bought 14 months ago and the boxes are different than the plain cardboard in your photos. Mine have the green & black Dayton graphics on the top and two sides. I got a bad one too. The replacement should be here any day...I hope.
  • I don't know, except for changed off-axis response. Beyond that- we'll see! :)
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