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Old 12th March 2011, 09:56 PM   #611
Djim is offline Djim  Netherlands
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Oliver, I have made a more accurate version and gave letters to the new reference points and where they end up in the horizontal representation.
It shows how "NON gentle" this bend is in relation to the ideal path. Also it will show clearly significant loss in volume (marked as light brown area).
I hope this will clear things....
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Last edited by Djim; 12th March 2011 at 09:59 PM.
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Old 12th March 2011, 10:19 PM   #612
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Djim; Thats why I droped the bottom of my box. Its no longer a single sheet box but should do better SPL wise. Andy
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Old 12th March 2011, 10:21 PM   #613
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I would have used 5 ref points per corner when I unfolded my box but thats to much to do by hand. Andy
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Old 12th March 2011, 10:25 PM   #614
Djim is offline Djim  Netherlands
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Andy, that's one way of doing it but I think it is possible within the one-sheet-challenge. And you should hear the difference clearly if you are going to its max power (less power compression in the lowest part of the bandpass).

In the 'old' days we used a reference point every 5 or 10 cm in a bend. Just to make sure corner bracing was nowhere touching the 'ideal' path. And to much off line resulted in burning your hands by steaming two layers of tri-plex and glueing/montage under pressure.

Last edited by Djim; 12th March 2011 at 10:30 PM.
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Old 12th March 2011, 10:29 PM   #615
tb46 is offline tb46  United States
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Hi Djim,

English (or whatever that is we are speaking here in Texas) is my second language too.

Thanks for elaborating, there is one point though, in Xoc1's plot the length are entered centered on the distance line, which would be best represented in the side view by lines that are orthagonal to the acoustic centerlines of the straight horn sections. so I would suggest to use points 8-F-11 and additionally to place points in between 8 and F, and F and 11 from the halfway point between 8-F-11 to the inside of the corner. That should give close correspondence between the side view and the profile (roll-out, horizontal representation).

Well, back to the joint cement and plaster board.

Regards,
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Oliver
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Old 12th March 2011, 10:46 PM   #616
Djim is offline Djim  Netherlands
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Quote:
Originally Posted by tb46 View Post
there is one point though, in Xoc1's plot the length are entered centered on the distance line, which would be best represented in the side view by lines that are orthagonal to the acoustic centerlines of the straight horn sections.
Exactly, if you want to find the acoustic centrelines. But I don't need to find it here. For this matter I want the most accurate outlines in my roll-out to see the real cab. I think that is the way to see these spots on their correct points on the horizontal axis. And I'll will show you another 'trick' that might work after you corrected a big bend.
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Old 12th March 2011, 11:31 PM   #617
Djim is offline Djim  Netherlands
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Okay, after you used all corrections and redraw the cab you can make a new roll-out (horizontal representation of the cab).

Instead of using corner bracing I was thinking of using one from the centre point! The idea behind this is that the large soundwaves don't see smaller objects so a small bracing in the centre wont hurt them. The volume it takes is almost nothing but you wont loose the volume from corner bracing on the outside of the path.

But it forces the low speed air molecules (that are using the shortest path) to raise their speed around the centre of the corner. Also it extends the shortest route within the horn. How much it works positive (or negative perhaps?) in the low end of the bandpass, I have no idea...

A few notes:
1.) It only can work in big corners.
2.) The length is set out between the difference between the ideal path (based on the reference point/line that hits the corner) and the extra length in the corner. I made it more clear in the roll-out (hor.repr.)

Any suggestions or comments?
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Last edited by Djim; 12th March 2011 at 11:47 PM.
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Old 13th March 2011, 01:48 AM   #618
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Yes but you still have a big restriction after that at point H between points 10 and 11.
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Old 13th March 2011, 03:07 AM   #619
Djim is offline Djim  Netherlands
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Quote:
Originally Posted by 4pyros View Post
Yes but you still have a big restriction after that at point H between points 10 and 11.
Not if you use my suggestion about lifting the driverpanel upwards. That way you can make up for some 'lost' volume in that area. Not completly, I agree on that, but enough to see changes in gain (I hope). But like I said I'm only looking for changes that fall within the one -sheet-challenge so I have to deal with that.
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Old 13th March 2011, 03:26 AM   #620
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OK then make S1 and S2 smaller? Why did you open up the S1 area again? Andy
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