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  • 6thplanet
    replied
    Cool build Jonny! Nice to see outta the box thinking/design. I look forward to seeing them at the show!

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  • dlneubec
    replied
    I used to have a pair of Infinity speakers (back in about 1975) that had a walsh supertweeter on top that sent out a 360º spherical horizontal wave. It looked kinda like an ice cream cone. I think the supertweeter on those kicked in right around 10khz, so yours should have a similar effect.

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  • dlneubec
    replied
    Originally posted by jhollander View Post
    Wow, I had never thought about that. Dan how did you make the big deflector cones?

    Currently I need something from 10K up for the AMT. The deflector is sized to reflect from 4K up. I just finish the proof of concept for mounting the tweeter. I'm pretty much committed to the current path
    Looks like you are cruising right along!

    Yeah, those diffuser cones were something else. I laminated pieces of mdf and purple heart together into a stepped cone (don't ask me why). My son-in-law was able to mess with them with a CNC he had access to at IU in the art department, and get them down to maybe 1/4" stair steps. Then, iirc, I figured out a way to spin them on my drill press and sand them down the rest of the way. Then I had to carve out the inside of the diffuser cones to accept a 6" dia waveguide with neo tweeter at the throat. It was a royal pain and not something I would ever do again!

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  • skatz
    replied
    John

    I don't know how you intend to use the spheres, but it occurred to me that maybe you could use world globes for fabricating what you want. I also recall seeing, I think on YouTube, a method of laying papier mache over balloons to make spheres. Are these to be reflectors that need to be hard? There are also glass globes that are used as lamp diffusers that might help you.

    Leave a comment:


  • jhollander
    replied
    Wow, I had never thought about that. Dan how did you make the big deflector cones?

    Currently I need something from 10K up for the AMT. The deflector is sized to reflect from 4K up. I just finish the proof of concept for mounting the tweeter. I'm pretty much committed to the current path

    Leave a comment:


  • Wolf
    replied
    Yep- the waveguide-Omni design.
    Wolf

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  • dlneubec
    replied
    I was talking about these:

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  • Wolf
    replied
    Dan, are you talking about your Duevel clone? I don't think you ever brought those to InDIYana, but you did bring it to CKY-DIY. If you mean the older Waveguide Omni with the purple-heart finished conical waveguide, yes those were at one of the 2 Richmond events. I think you brought it back later just for a little more exposure.

    Later,
    Wolf

    Leave a comment:


  • dlneubec
    replied
    John,
    Have you thought about placing your tweeter in a shallow waveguide with the diffuser above? I did a lot of experimenting with this omni tweeter concept. I even had a prototype speaker that I brought to an early InDIYana. I never finished it, but my recollection is that I obtained the smoothest response when the tweeter was also depressed into a waveguide. It might be more complicated than you want for this project, however.

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  • Wolf
    replied
    If you want large spheres, how large? Meijer stocks 8" Styrofoam halves that are meant to be adhered together if that works for you.

    Later,
    Wolf

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  • jhollander
    replied
    Ken thanks but as I mentioned there were a lot of people who helped me with this project. One of them was TN Allen who made me some deflectors. Once I get closer I'll take some pictures of Tim's work.

    Dan, I'm saving my Omni ideas for 2020 Fort Wayne Indiana. Unfortunately it involves sourcing some affordable large spheres.

    I've decided on the RS180P-4 woofer in 20 liters which should give me a F3 of about 40 Hz. The super tweeter is going to be the ND25FN. I've started cutting wood and should post some more pics.

    Drawings look like this.

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  • kenrhodes
    replied
    John, I would be willing to try to 3d print the diffuser. My printer is limited to about an 8 inch cube. If I can help let me know.

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  • dlneubec
    replied
    Sounds like a good plan. What I was actually wondering about when I mentioned implementation was whether it was going to be sealed, cardioid or open back. Sounds like you are going sealed.

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  • jhollander
    replied
    I wish the AMT was a bit of a mid, but the best I think I can get is near 2K depending on the sensitivity of the woofer. The AMT is going to go in a small box with a big round over on top of the bigger box with a big round over. The idea is that the small box can move back and forth so I can time align the AMT and the woofer.

    I've decided to try to make this for MWAF so the original design with round cylinders has changed to sqarish boxes with big round overs. The new design is a bit slimmer.

    Leave a comment:


  • dlneubec
    replied
    I think you are on the right track with this. You may have already factored this into your dimensions, but I think you would have the best result if the wavelengths generated by the tweeter, maybe to an octave lower than the crossover point, are not so long that they just ignore the reflector, go around it and head straight up. I think you will probably have the best result with the tip as close to the dome as possible, but when you prototype this you might want to make the reflector adjustable up and down, then you can take measurements to determine the optimal distance from the dome.

    How are you planning to implement the AMT mid?

    Leave a comment:

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