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Old 18th December 2012, 04:03 AM   #781
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Quote:
Originally Posted by xrk971 View Post
Klampy,
If you stretch it in one direction, the path lengths of the nominally 2 x long and 2 x short horns will change to have 4 different lengths. This may be an advantage by having multi horn frequencies blend to be smoother in output frequency.
that makes pretty good sense actually. without specs on the driver (annoying as for a pro audio brand..) any suggestion on a recommended scale? driver has a pretty low Fs, like around 30-40hz. big power handling, and fairly subdued midbass/midrange output.
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Old 18th December 2012, 10:25 AM   #782
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Quote:
Originally Posted by klampykixx View Post
that makes pretty good sense actually. without specs on the driver (annoying as for a pro audio brand..) any suggestion on a recommended scale? driver has a pretty low Fs, like around 30-40hz. big power handling, and fairly subdued midbass/midrange output.
The 70 cm square has a nominal freq of 38 Hz according to longest path. If doing a 6 x9 you would need to scale the short dimension by 6/5 x 70 cm = 84 cm, and the long by 9/5 x 70 cm = 126 cm. It will be BIG looking, but very cool, with probably an average tuning freq down in the 25 Hz range - I am guessing, based on linear scaling arguments.... Give it a try
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Old 18th December 2012, 10:40 AM   #783
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wow, thats bigger than the horn i was gonna do for my 8inch driver. (insert epic sad face here)

my biggest problem is the fact that im in the garage, at a computer desk with my laptop. i need/want something thats somewhat small enough to sit on my desk, on either side of my laptop, and still sound awesome.

if i run the 4inch coaxial drivers, it would be 70cm^2 still to attain a theoretical tuning of 38hz? even thats probably still a bit big, i only have 120cm from end to end of the table...

what im thinking is a rectangle box, 120cm wide, 60cm tall, (two squares) but with a single(maybe double) spiral so one exits the top, and one on each side of the main box.

that way, ill get good stereo imaging, and the bass will eminate from the top and sides of the cab.

so, any ideas what will happen differently having two spiral paths rather than four? the top one would actually become one mouth, rather than two as id twist the left one to spiral out anticlockwise, and the right one spiral out clockwise.

what you think?
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Old 18th December 2012, 11:01 AM   #784
xrk971 is online now xrk971  United States
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Klampy,
The 4 in coaxials can probably work in the 50 cm (20 in) if you are trying to keep size small. The side by side stereo is a cool idea, mod the plan to have only 2 spirals on each side with outputs at top and sides. That's the fun and beauty with foam.... easy to try.
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Old 18th December 2012, 11:35 AM   #785
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absolutely. ok, so what i might do is wait till new years before i start this, as i have a cash injection heading my way at that time. id love to have a nice stained laquered front panel, so i think ill do it out of ply. it will make a nice backdrop on my desk for producing on. i think , based on me playing with digital EQ and DSP etc, i can make it work the way i need it to.
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Old 18th December 2012, 12:26 PM   #786
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Originally Posted by xrk971 View Post
The TC9FD needs no tweeter, you would be adding the messy crossover into an otherwise Nice FR. Maybe a sub to make it into a FAST but no tweeter.
As I haven't listened to the Vifas yet, my reference to a two way was based on a couple posts I had read. Hopefully I'm in for a pleasant surprise.

Several years ago I bought a dozen buy-outs that have produced great bass in a couple different cabinets.

Stanford MSF100B20U
20 W
89 db
fs=68.5
vas=4 ltr
qms=1.86
qes=.43
qts=.35
to=3K

They matched the Audax I mentioned quite well. After I finish the 24" Vifa build I'll try another with that combo.

One forward - two back: The luan I planed to use was too old. As soon as I cut it to size the panels curled up and became unusable. I glued two opposing curves together and that resulted in a flat double panel. I'll buy some new wood today for the other two.

Also, I may have missed any suggestions of an easy way to sale the pattern to different dimensions. I ended up using Corel Draw in poster print mode. The PDF is offered for anyone interested in a 24" version. For super accuracy, there are match marks that can either be cut or one can use a pin or needle to punch through while taping the pages together. (May depend on printer driver)
Attached Images
File Type: jpg Marks.jpg (44.4 KB, 388 views)
Attached Files
File Type: pdf 24 inch Final_Mks.pdf (114.2 KB, 41 views)
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Old 18th December 2012, 02:09 PM   #787
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Planet10 made a very vector pdf plan for the cornu that you can scale. Somewhere back on page circa 40 something? You will be happy with the Vifa's top end. See Pano's measurement here:Ever think of building a Cornu Spiral horn? Now you can!
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Old 18th December 2012, 02:19 PM   #788
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Thanks, I have that PDF and a couple others. I'm all set now, but for future reference what is suggested as the best method/software for doing the scaling. I created a 24" X 24" layout in Corel, cropped out everything (ledger line extensions) outside the edges of the foam and then manually adjusted all four sides to match the template. If there is an easier method - I'm all ears.
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Old 18th December 2012, 02:33 PM   #789
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Originally Posted by xrk971 View Post
Planet10 made a very vector pdf plan for the cornu that you can scale. Somewhere back on page circa 40 something?
Here: page 23
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Old 18th December 2012, 03:19 PM   #790
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Originally Posted by bcmbob View Post
Thanks, I have that PDF and a couple others. I'm all set now, but for future reference what is suggested as the best method/software for doing the scaling. I created a 24" X 24" layout in Corel, cropped out everything (ledger line extensions) outside the edges of the foam and then manually adjusted all four sides to match the template. If there is an easier method - I'm all ears.
Bob.
If you print the pdf using Adobe Acrobat Reader X (recent version 10.1.4), in the file/print menu dialog, there is an option under Paper and Page Handling called "Print Poster". Here, you can choose scaling in percent and give overlap and cut marks, etc. Using Planet10's pdf (Foam Core Board Speaker Enclosures? post #230 ) when I select "Print to Scale" it prints the cornu out as a 7.0 inch scale. So to get a 24 inch you need to scale 7.0x3.428=24.0 inches. So in this example scale the drawing by 343% and I selected 0.5 in for overlap to give enough room for taping or gluing them together. It will generate 15 pages (3x5) of 8x11.5 sheets that you will have to piece together. It may be helpful to select "Cut Marks" and "labeling" so you do not have to work it like a puzzle. I tested this and it works. For some reason it uses more paper when you select "Cut marks". Hope this helps.
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Last edited by xrk971; 18th December 2012 at 03:21 PM.
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