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Old 13th March 2011, 08:52 PM   #631
tb46 is offline tb46  United States
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Hi Xoc1,

The pdf files in Post #74 & 82 are still the ones I work of, I used them as a base for Post #622.

There is some room for cleaning up the SS15 drawings, e.g.: getting the corners tight, and getting the dimensions of the wood pieces after cutting. I just couldn't see any reason for doing so, there has to be a little diy left for the individual builders. Same holds for improving the output, I think that within this form factor this is about all you can get out of the 3015LF. I still would like to see somebody measuring what happens when you set S1 to zero, and slant a board up from there to S2. According to Hornresp that would be an improvement. Jbell's explanation for how he arrived at the shape is interesting, one might be able to redesign the path to fit even better, but would it make a difference?

I really enjoy your drawings, very nice work. Looking forward to seeing what you'll do with this one.

Regards,
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Old 13th March 2011, 09:02 PM   #632
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Quote:
Responding again to your question in Post #583: "Can you get it to bend at S3?" I changed the flare from S2 to S3 to an even 3degrees, and then started into the same angle as your driver mounting board, that will do it, no major change in Hornresp:
Oliver; Sorry I must be lost somewhare. Does your program automatically put the purple line in? I was not looking for a new S3 locashoin just a bend at the orginal S3 locashoin. Like in the one for Jims box. Andy
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Old 13th March 2011, 09:11 PM   #633
Djim is offline Djim  Netherlands
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Oliver, many, many thanks.

For the middle path in corners I show you a drawing how I prevent 90 degree pathways (sound waves can bounce in 90 degrees only on hard surfaces). Btw, I use 2 x pi in bends for setting out the middle path...

And if it is not to much to ask for you and Martin, could you make a scale above the roll-outs with metric numbers every 10 cm (and tiny stripes for each cm, see picture). I don't like to ask you Oliver as I know it is time consuming but your excel sheet is in inches only. When I tried to change it I messed it up

As you can see your PDF files (in 100% scale) don’t line up with metric scale above it. For me that isn’t big problem as long you provide a metric scale aligned with the path. That way I can input your PDF’s in Photoshop en re-scale them to 'real' centimetres, perfect for prints and other metric graphs.

Anyways, it is great stuff you guys are producing!
Attached Images
File Type: jpg TB_cor_01.jpg (42.3 KB, 357 views)
File Type: jpg TB_cor_02.jpg (65.0 KB, 352 views)

Last edited by Djim; 13th March 2011 at 09:22 PM.
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Old 13th March 2011, 10:23 PM   #634
tb46 is offline tb46  United States
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Hi Djim

Well, one more time (again, rename the .txt file .xls):

Regards,
Attached Files
File Type: pdf 2011_Mar12_SS15_profile_revised_grid.pdf (68.6 KB, 86 views)
File Type: txt jbells_singlesheet_soho54_Xoc1_tb46_numbers.txt (18.1 KB, 42 views)
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Old 13th March 2011, 10:37 PM   #635
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Quote:
Originally Posted by Xoc1 View Post
Jbell post 12

Quote:
BTW -- leaving out the bottom panel and saying "just sit it on the floor" is cheating.....
I might be interested in cheating then... Who's with me?
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Old 13th March 2011, 10:42 PM   #636
Djim is offline Djim  Netherlands
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Wow Oliver, you do that quicker then I can make an example picture...
Thanks
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Old 14th March 2011, 12:17 AM   #637
tb46 is offline tb46  United States
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Hi Djim,

Had to hurry, I'm in the middle of an interminable remodelling project. :-) Well, back to the joint cement, one more layer on this doorway.

Hope it helps.

Regards,
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Old 14th March 2011, 04:26 AM   #638
Djim is offline Djim  Netherlands
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Sure it helps, now I can show JBell in detail where his SS15 can be improved.

The air resistance point is situated between points 40 and 41. Here the path of the horn is squeezed together. This can be translated to the 78Hz area. I also coloured the whole area where the real cab is less in volume compared to the predicted model to make it more visual.

JBell measurement...Runrod1948 measurement

40hz 98.5.............40hz 101db
45hz 100.5...........45hz 104db
50hz 102..............50hz 108db
55hz 103.5...........55hz 109db
60hz 105..............60hz 111db
65hz 105..............65hz 111db
70hz 105..............70hz 112db
75hz 104.5...........75hz 112db
80hz 104.2...........80hz 110db
85hz 104..............85hz 112db
90hz 104..............90hz 113db
95hz 104..............95hz 112db
100hz 104.5..........100hz 113db
105hz 105............105hz 112db
110hz 105............110hz 112db
115hz 105.5..........115hz 113db
120hz 106.5..........120hz 113db

So please can anyone tell me; bad theory and another coincidence or correct theory and exact numbers showed by a lovely model of horizontal representation?
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File Type: jpg TB_roll-out_06.jpg (84.6 KB, 338 views)

Last edited by Djim; 14th March 2011 at 04:30 AM.
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Old 14th March 2011, 06:25 PM   #639
Djim is offline Djim  Netherlands
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Another air resistance point you can find around point 21. Here is the narrowing also more then 1/6 of the path. It's centre frequency is 186Hz. The narrowing starts around 177Hz and ends around 195Hz.

I'm not sure what HornResp produces around this freq since I have seen several predictions (which one is closest?). If predictions already predict a notch around this frequency, the reality will be a more deep and wider notch then predicted. If you want to use the SS15 bandpass around this frequency, you can correct this point.
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File Type: jpg TB_roll-out_07.jpg (91.4 KB, 417 views)

Last edited by Djim; 14th March 2011 at 06:28 PM.
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Old 14th March 2011, 06:29 PM   #640
AndrewT is offline AndrewT  Scotland
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Are these pinch points designed into the flow path?
Are we/you measuring the layout accurately?

There is no reason to insert a restriction around a bend, if the design does not need a restriction.
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