Announcement

Collapse
No announcement yet.

C-Cake Design and build log

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • kenny_k
    replied
    You could try a hemisphere to mount the tweeter. Maybe suspend the tweeter on a stalk facing down toward the reflector?
    Last edited by kenny_k; 06-06-2019, 02:20 AM. Reason: a new idea

    Leave a comment:


  • rpb
    replied
    Originally posted by jhollander View Post
    Here's my test setup. As dlneubec mentioned the reflector close to the dome gave the best measurement. That's about 1 mm in the last picture. What I found annoying is that my bracket causes a big dip on axis. I had planned a round over but that is not going to help much. I need another idea. I thought about two small posts but I don't like the look. I'm leaning toward similar bracket but on a 45 degree angle. Whatever I come up with has to be somewhat adjustable if I'm going to get 1 mm clearance from the dome.
    Maybe cut a series of horizontal notches with the depth adjusted to cancel the offending frequency. My other thought was to cut a series of 5/8" holes to allow the sound to go through the brace.

    Leave a comment:


  • jhollander
    replied
    Thanks guys. Good ideas here. Yes the dip is due to the flat face of the bracket. As I rotate the bracket off axis the dip(s) go away. I had not thought about the 45 degree angle but that makes sense. I certainly think I can aim the dip off axis as well.

    Leave a comment:


  • skatz
    replied
    You did see this that someone posted recently?
    https://www.youtube.com/watch?v=9FNwSQb7mww

    Leave a comment:


  • skatz
    replied
    If it was a permanent installation you could suspend the deflector from the ceiling, but I don't think you really want to do that. If you do it as Dan suggests and present 45 degree angles to the dome and mount it at the back, it would deflect those reflections to the sides, where listeners aren't (I presume).

    Leave a comment:


  • dlneubec
    replied
    Originally posted by jhollander View Post
    Here's my test setup. As dlneubec mentioned the reflector close to the dome gave the best measurement. That's about 1 mm in the last picture. What I found annoying is that my bracket causes a big dip on axis. I had planned a round over but that is not going to help much. I need another idea. I thought about two small posts but I don't like the look. I'm leaning toward similar bracket but on a 45 degree angle. Whatever I come up with has to be somewhat adjustable if I'm going to get 1 mm clearance from the dome.
    John, I'm thinking you may be able to mitigate that by just routing 45's on the face of your bracket, so that it presents a pointed edge toward the done rather than a flat edge. Any dip should be substantially reduced and may only occur off axis, if at all. I assume you are getting an out of phase reflection back to the dome with that flat surface so close behind it.

    Another option would be to create a bracket arm that runs up the back of the box and does not mount on top surface. This would push the arm out far enough that the reflection, would occur below the XO point. If it were me, I would probably to a combination of both were I presented 45's toward the dome and also moved the mount arm as far away as feasible.

    Leave a comment:


  • kenrhodes
    replied
    Linkawitz used a mirror to "aim" the baffles dipole notch so that he would have less reflective sound going to the listener.
    Could you "aim" the notch to cancel of axis problems?

    Leave a comment:


  • jhollander
    replied
    Here's my test setup. As dlneubec mentioned the reflector close to the dome gave the best measurement. That's about 1 mm in the last picture. What I found annoying is that my bracket causes a big dip on axis. I had planned a round over but that is not going to help much. I need another idea. I thought about two small posts but I don't like the look. I'm leaning toward similar bracket but on a 45 degree angle. Whatever I come up with has to be somewhat adjustable if I'm going to get 1 mm clearance from the dome.

    Leave a comment:


  • jhollander
    replied
    Hear are some pictures of the deflectors from TN Allen and my tweeter mounting

    Leave a comment:


  • jhollander
    replied
    A little more work. I got the top cabinets assembled. I used CA glue to reinforce the MDF for the super tweeter recess. Thanks to Mike C who CNCed my AMT3-4 recesses in small pieces of MDF. This saved me a ton of time compared to routeing and cutting down

    Both the top cabinets and base cabinets were flattened with a combination of hand planes and sandpaper glued to MDF blocks. When I used my store bought sanding blocks and power sanders they tended to dish and roll over the edges, definitely not flat.

    I'm working on the deflector and supper tweeter mounting next. I'll cut the woofer holes before I start the round over process. Probably not happening soon as this is going to be a long fishing weekend.
    Last edited by jhollander; 05-14-2019, 09:16 PM. Reason: add super for clarity

    Leave a comment:


  • Wolf
    replied
    I'm still mulling it over. Likely the week before Dayton as usual. Right now I'm in build mode.
    Wolf

    Leave a comment:


  • jhollander
    replied
    Ben, feel free to suggest away. I've got a pair of the OT19s as back up https://www.parts-express.com/peerle...-ohm--264-1122

    The ring radiator/ center "post" tweeters worked well in my wave guide tests as the post acted like a phase plug preventing a bigger on axis dip. I've discounted that benefit when using a reflector, everything is off axis. I still need to do a bit of testing but I'm not to concerned as I don't need much FR for the super tweeter.

    I'm looking forward to your post for InDIYana 2020. I've already pulled down about 10 omni patents for ideas.

    Leave a comment:


  • Wolf
    replied
    Couldn't you use a dimple dome and set the apex right in the dimple? Or set the tip of an XT25 right on it? It's been said more than once that ring radiators suit waveguides better. Just suggesting out loud, not telling you what to do.

    Wolf

    Leave a comment:


  • AEIOU
    replied
    Originally posted by jhollander View Post
    What every speaker needs, a Mark and Daniel Omni Harmonizer. So add it all together this is the first design I came up with. It's based on using 12 inch and 8 inch round cylinders.
    This is how Henry Wolcott did it, an omnidirectional horn (on the horizontal plane) using only a single dome tweeter. Initially the Dynaudio D28, later on the Morel MDT33.
    Sorry for the poor picture, but if you squint you should be able to see the tweeter dome. LOL

    Click image for larger version

Name:	Omni_sp_top.gif
Views:	15
Size:	7.2 KB
ID:	1412766

    Leave a comment:


  • jhollander
    replied
    Eric, thanks your build was also motivation to get started.

    Bottom box and box model. I've convinced myself that an internal offset port end will miss some of the resonance trash inside the speakers. There were more braces added than the few shown here.

    Leave a comment:

Working...
X