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Get familiar with the reaction system: Introducing the Reaction System
Slit cones
I've been thinking about slit cones. I realize that it is not exactly the same because a saw blade manufacturer is only concerned about the effects at the rim of the blade body, but I couldn't help notice the similarities. Slots cut and filled with a compound to dampen unwanted resonances.
Comments
I thought those were to prevent warping as the blade unevenly heats from friction/pressure from its perimeter to center point?
Or maybe we mean the same thing?
I looked at my table and miter saw blades and could not see damping material in the slots. Most of them simply had slots cut in them at various places, but no damping material. How do your blades respond to the standard knucle rap test? My blades ring like a bell.
It depends, lots of variables. David, A4eaudio seemed to make a lot of sense with his slit cone mid. Pro mid with a lightweight cone. Or maybe it was a fullrange. I don't remember exactly. I know slightly more about saw blades than speakers. Speakers are not as simple as they appear.
That's called an understatement
https://parts-express.com/Dayton-Audio-PM180-8-6-1-2-Wideband-Midbass-Neo-Driver-295-343?quantity=1
https://techtalk.parts-express.com/forum/tech-talk-forum/66754-how-to-train-your-pm180-8
I would bet the slits localize the resonance, preventing it from combining with the other resonance energy into one large scale (lower frequency) resonance. The damping material helps shed that energy.
This year's was the PM180-8 as linked by Drewsbrews. I did not measure before and after because Josh Brunner really documented it well in that thread. Last year I experimented with the $36 SB26PFCR before attempting it on the more expensive driver. With the SB26 I measured before and after and it really did make a significant difference in reducing cone breakup and distortion.
I like both... slits and cones.
Whoa!
Huh huh huh huh huh, yeah....slits...huhuhuhuhuhu
other than just "eyeballing" the slits, is there any kind of guide for cutting the cones?
Most I've seen attempted followed the pattern of the Revelator.
InDIYana Event Website
That appears to be what Josh Brunner did. He wrote that he slit the cone with an Xacto knife then drug the blade backwards through the cut to widen it. I forget what adhesive/caulk he used though.
2 glues were mentioned for the slits - DAP Alex Plus clear caulk or Gem-Tac.
I have an RS225 that I plan to experiment on.
I first practiced on some $3 4-inch buyouts, then I used the SB16PFC and finally the PM180s. For the first ones I calculated the circumference and divided by 5 and just marked that distance on an index card. For the PM180s I calculated the circumference of outside and inside edge of cone, added symmetrical markings and printed on regular printer paper. I don't think the extra work made me much more accurate than the index card.
I have a little set of exacto knives for doing wallpaper. Slicing the cone isn't hard but the key is to have your blade going in the exact direction you want. The SB16PFC is thicker and I had to push pretty hard. (I held the back of the cone with my other hand for resistance making sure my fingers were not where the blade was going to come through.) The cone resists and resists and then when the blade goes through it goes through all at once. So if I wasn't pointed accurately it would create a cut about 1/2" long a little off from where I wanted. I could then change direction to get back on target but that little change in direction was visible. This last time I bought a Japanese corrugated cardboard cutting tool. It worked except I had some "frayed" edges. I thought these wouldn't show once I added the glue but I was wrong. I probably could have trimmed up the frayed edges if I had known.
The one thing that I haven't got quite right is the glue line. Josh seemed to have this down impressively. I used DAP Alex Plus with silicone. This is what Josh settled on because I asked him via PM. My glue lines are a little sloppy. I bought some glue syringes with multiple tips this last time but I still didn't do a great job. So one recommendation is to practice the glue lines on some buyout drivers, cardboard or construction paper.
I'd almost expect the caulk to be pulled right out when trying to wipe off excess. Acrylic caulk will clean up with water, but silicone needs alcohol. Maybe 50% isopropyl would do?
I have an extra diode laser that could cut paper really easily. It should leave a really fine curf. Maybe it's time I jumped on the bandwagon.
Has anyone tried a poly cone?
how would you position the speaker on the lazer bed - the lazer needs to be at a constant distance from the surface
Very carefully?
Sounds risky. Why not just dab a bit of damping material of choice, instead of cuts? Has anyone tried this and compared results?
The focal distance isn't very far from the tip so I was thinking of adding a "stylis" that would maintain the focal distance and give me a tip that I can aim. Laser exacto blade.
Yes, people have experimented with that. If you don't cut all the way through, but instead just add "stuff" to the front or the back of the cone, it doesn't do anything.
But but but what about those dots? LOL
My wife has a CO2 laser with an extra lens with a 4 inch focal length. she also has a rotary device, although I think it would still take some serious shimming between the table and rotary the make the cone close to level. If I make a delicious dinner tonight and the stars align just right, I may bring it up. I would have to pack something behind the cone to protect the tinsel leads and reduce reflections to the back side of the cone. I would thing that a longer focal length would be more forgiving of distance differences.
The laser cut and filled slots in saw blades began to appear after the introduction of thin kerf blades from makita and others to address the reduced cut quality from vibrations. I think. Pretty sure.
Maybe use some aluminum behind the cone / in front of the spider for protection.
Or steel wool. This will be an excellent opportunity to get rid of some cheap ass drivers on the shelf
You could start a house fire after burning the driver up with steel wool - it is highly flammable.
Just a thought - how about a dry sponge instead?