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-   -   Elliptical guides for the LD25X (http://www.diyaudio.com/forums/css/222765-elliptical-guides-ld25x.html)

Dave Pellegrene 3rd November 2012 02:58 AM

Elliptical guides for the LD25X
 
Thought I'd take some time and post a couple of guides I've been working on. I ran two of them with the base plate for the LD25X.
This guide is 5 3/8" (135mm) x 3 15/16" (100mm)
These are 0 20 30 40 50 60 degree axis measurements.
https://lh4.googleusercontent.com/-L...050%252060.png

5 3/8" (135mm) x 3 15/16" (100mm)
These are 0 20 30 40 50 60 vertical axis
https://lh3.googleusercontent.com/-R...52060%2520.png

This guide is 7 1/8" (180mm) x 4 15/16" (125mm)
measurements taken at 0 20 30 40 50 60 degree axis
https://lh5.googleusercontent.com/-9...52060%2520.png

7 1/8" (180mm) x 4 15/16" (125mm)
measurements taken at 0 20 30 40 50 60 Vertical axis
https://lh4.googleusercontent.com/-i...050%252060.png

This is the 8' version Bob has know. I couldn't find a flat baffle measurement so I'll post this one for comparison. All three sets of measurements were taken on a 10.5" wide baffle with a 30 degree chamfer.
https://lh6.googleusercontent.com/-_...050%252060.png

Dave

tuxedocivic 3rd November 2012 04:08 AM

Hey Dave, nice to see you over here.

I fancy little waveguides for domes, so that first one appeals to me. Nice looking. Better spreading in the higher frequencies than the others IMO. Did you do any verticals for the ellipticals by any chance?

Keep the good guides coming Dave :D

Dave Pellegrene 3rd November 2012 05:45 AM

Quote:

Originally Posted by tuxedocivic (Post 3226049)
Hey Dave, nice to see you over here.

I fancy little waveguides for domes, so that first one appeals to me. Nice looking. Better spreading in the higher frequencies than the others IMO. Did you do any verticals for the ellipticals by any chance?

Keep the good guides coming Dave :D

Put the verticals up in the first post.
I've been looking into polar plots but from what I have found out so far I need to buy an omni mic. I haven't found a way to do it with HOLMImpulse yet.

Dave

Dave

Dave Pellegrene 3rd November 2012 05:51 AM

Quote:

Originally Posted by tuxedocivic (Post 3226049)
Hey Dave, nice to see you over here.

I fancy little waveguides for domes, so that first one appeals to me. Nice looking. Better spreading in the higher frequencies than the others IMO. Did you do any verticals for the ellipticals by any chance?

Keep the good guides coming Dave :D


Well I posted that I put the verticals up and it's not here. Anyway I put them in the first post.

Dave

tuxedocivic 3rd November 2012 09:28 PM

Sweet. I still like the first one. A little loss of directivity down below 3k, but pretty good.

Do these have low end gain compared to the flat baffle? Compared to my measurements I'd say they do have some. My aveguide measurement shows more gain than that though.

Got any pics of that first one?!

Dave Pellegrene 4th November 2012 02:36 AM

Quote:

Originally Posted by tuxedocivic (Post 3226880)
Sweet. I still like the first one. A little loss of directivity down below 3k, but pretty good.

Do these have low end gain compared to the flat baffle? Compared to my measurements I'd say they do have some. My aveguide measurement shows more gain than that though.

Got any pics of that first one?!


Here is a flat baffle measurement on the same baffle.
https://lh5.googleusercontent.com/-_...050%252060.png

Flat baffle (blue), 135mmx100mm (red), 180mmx125mm(green) on axis
https://lh6.googleusercontent.com/-N...n%2520axis.png

This is the guide with the SB29 in it.
This is a new one I've been working on. It's not completely elliptical. If you look closely it has a rectangular look to it. The four corners are eased back.
https://lh6.googleusercontent.com/-S...mm%2520004.jpg

I'll have to take a pic with the LD25X in it and replace this one. Sorry Bob!
My daughter wanted to know what I did to the tweeter. Thought I poked it in. :)

Dave

RAW 8th November 2012 05:46 PM

Dave
Great work on the wave guides.
I am doing some designs for Bob using the round wave guide you designed for him. The first design is almost done. I have used the motus woofer and the LDX 25 in the round wave guide in a single fold T line. Plus the same driver and wave guide combo in a monitor.
The round wave guide is great and I look forward to working with the new wave guide.

Keep up the great work.
Al

Dave Pellegrene 13th November 2012 02:49 PM

Quote:

Originally Posted by RAW (Post 3233657)
Dave
Great work on the wave guides.
I am doing some designs for Bob using the round wave guide you designed for him. The first design is almost done. I have used the motus woofer and the LDX 25 in the round wave guide in a single fold T line. Plus the same driver and wave guide combo in a monitor.
The round wave guide is great and I look forward to working with the new wave guide.

Keep up the great work.
Al

Glad you like the guides. I'll get a few of the elliptical ones made up.
I've recently changed my measuring set up to be able to measure 0 - 180 degrees and do polar plots. What do most like to see 10 degree increments?
Dave

Dave Pellegrene 13th November 2012 03:18 PM

Quote:

Originally Posted by tuxedocivic (Post 3226880)
Do these have low end gain compared to the flat baffle? Compared to my measurements I'd say they do have some.

The few guides I've made for Dan N. for the Echelons, the Chameleons and a few others seem to show more bottom end boost in his measurements then in mine. I've found I measure more boost if I'm measuring the guide sitting on ridged fiberglass as a baffle vs a wood baffle. I try to keep the measurement set up the same for all the guides using a 10.5" wide baffle with 30 degree chamfers. This leaves just enough room for an 8" wide guide. It's then mounted to a 12" deep box. I usually see a 10 db boost compared to the flat baffle. On these particular guides I get less bottom end boost then the 8" round guide but that is to be expected with the smaller diameter guide.


Dave

tuxedocivic 13th November 2012 05:04 PM

10d is probably pretty good. Depends what I'm doing. I've done variable as well. As in, starting with 0, 5, 10, then 20, 30, then 45, 60, then 90, 135, 179.

I doubt you need more than 90d with those wavelengths. Unless you mean +90 to -90. I would just do 90d in one direction and mirror. The only time I wouldn't is with a completed speaker with asymmetrical driver layout.


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