I'm playing with the idea of taking a pair of Ikea Blanda bowls, a coax or fullrange driver, poke some holes in it, and cover them with felt and hopefully end up with something like the cardioid ball from Gradient 1.4. What could go wrong right?
The Gradient 1.4 ball have it's vent on the back instead of the sides like most other cardioid speakers.
Couldn't one in theory have these anti-phase leaks on both the back, top, bottom and sides?
The Gradient 1.4 ball have it's vent on the back instead of the sides like most other cardioid speakers.
Couldn't one in theory have these anti-phase leaks on both the back, top, bottom and sides?
Couldn't you leave a restrictive gap between the two bowls? I'm unsure of the size of them, perhaps a stretchy sock could be persuaded to go around it? - an all encompassing grill cloth with a heal and toe...
Many Blanda bowl builds here. I am just working on one at the moment. for Alpair 7ms. Here is one i did for A5.2/3 (CHN-50).
dave
dave
Been working on the same idea for a while. Sica coax with an array of holes a few inches behind the driver for the cardioid part.
That's definitely a way to do it!
That's actually the exact driver I had in mind. Running them in a pair of basic BR enclosures now with slight EQ. Sounds wonderful.
But I'd like to see if I can improve the sound by reducing sound radiation to the back and side walls through some sort of cardioid pattern control.
Oh, exciting! Gotten any results? I wonder why Gradient chose to have the vent in the back as opposed to the sides. Or both.
The Alpair 5 has been built, it is in Spain, plans available as part of the miniOnken planset for the A5s. I assume the A7ms will get built, he has the bowls, he just needs the detail. Project set back by unexpected 8-day “holiday" at hospital.
dave
dave
What about combining the Blanda with the Gronsaker for a different look?
https://www.ikea.com/au/en/p/groensaker-serving-bowl-bamboo-40485731/
https://www.ikea.com/au/en/p/groensaker-serving-bowl-bamboo-40485731/
That is actually the variation i am working on for Roberto.
dave
dave
The semi-circular end. There will be a ~35mm spacer/vent structure between the 2 pushing the shape into more of a teardrop
dave
dave
Seems to be unavailable in Norway 🥲
Any plans on trying out some sort of cardioid radiation/vents with it?
Yeah, but "quality" of the response would differ with each variation. I mean, in order to cancel sound nicely you need the opposite phase sound leaking so that it travels like the sound diffracting around the box (or sphere in this case) from the front. This means, it needs to have similar frequency response, level, direction, delay, phase, to make it work as good as possible. If any of these differ there is less cancellation to a direction.
What I think, why boxy speakers have the vents close to front edge, is that edge diffraction makes the sound propagate "chaotically" on the box size bandwidth in a sense that it is very hard to match sound from the front with that from the back. Putting the vents near front edge has the best chance for match, as the sound from the back would diffract somewhat similarly and so on, still, it would be better to reduce edge diffraction.
On a sphere there is not much edge diffraction and related issues, and the sound from front is more predictable, it just propagates to all directions while some bandwidth goes around along the sphere some. Intuition says best place for vent is possibly on the back, because any sound that diffracts all around the "box" would pass on the back and if the vent output is timed good it would propagate right along with it cancelling out as good as possible. Also if the vent does diffraction perhaps its effect to listening window is reduced.
Well, anyway, it takes some experimenting with the back port to get good response. By luck you are fine enough with first try, its not too hard to experiment with the damping material try and get somewhat better / smoother response.
Yep, I would copy the Gradient port and then experiment with the damping, for easiest path to some success.
Have fun!🙂