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Old 29th December 2012, 07:51 PM   #201
xrk971 is online now xrk971  United States
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Originally Posted by planet10 View Post
Mass-Loaded Voigt. You can reduce the ripple by tapping the driver in part way down the line (Hoe you would do that phyisically is a different challenge.

dave
I was thinking that this can be implemented by making a driver chamber offset from the main spiral box and having 4 holes (slots) leading from driver chamber to 1/3 of the way from closed end of Voigt pipe. This will make a bump out chamber and not look so flat anymore. Although the horizontal dimensions would be reduced as the closed ends of each pipe can start in middle now.
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Old 29th December 2012, 07:53 PM   #202
xrk971 is online now xrk971  United States
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Cal,
Ordering the Vifa's is painless if Dave doesn't have what you are looking for, and we know it works well with this particular driver. The Vifa's have 2.5 mm of xmax which is particularly nice for kick drum sound.
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Old 29th December 2012, 07:58 PM   #203
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Just talked with Dave on the phone and it sounds like he will have something for me in a couple of weeks so in the meantime I need the true spiral drawing [not the rounded square one] so can you point me in the right direction or even post it again so I can get things ready?

Thanks.

EDIT: I found I have it downloaded already so I can go ahead with that.
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Old 29th December 2012, 08:49 PM   #204
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I had a look at the PDF I downloaded and I have some concerns. The channel is wider at the red arrow than the blue. Is that a problem?
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File Type: png Cornu with arrows.png (93.2 KB, 653 views)
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Old 29th December 2012, 08:56 PM   #205
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Originally Posted by Cal Weldon View Post
I had a look at the PDF I downloaded and I have some concerns. The channel is wider at the red arrow than the blue. Is that a problem?
Yes. The original i traced from was not very good. I've not had a chance to rework from 1st principals.

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Old 29th December 2012, 09:18 PM   #206
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Originally Posted by Cal Weldon View Post
I had a look at the PDF I downloaded and I have some concerns. The channel is wider at the red arrow than the blue. Is that a problem?
Cal,
The easy fix if you are in a hurry is to hand draw the spirals to make the round parts transition to the flats in a way that the tangent (slope) is zero. This can be done by moving the square external boundaries out to allow for more expansion of the curved part. It probably doesn't make too much of a difference.
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Old 29th December 2012, 09:47 PM   #207
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If Dave is planning to do it then I will wait. Otherwise I will do what you say. This is what Iwill be sending up north so it would be nice to have it better than hand drawn.
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Old 30th December 2012, 09:17 AM   #208
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I have been following this thread for a few days and today started to build a pair of these speakers. I don't really have a clue as to what I'm doing, but it sure is fun.
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Old 30th December 2012, 11:13 AM   #209
xrk971 is online now xrk971  United States
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Prezden,
Welcome on board! Glad you are having fun. The foam core thread has a lot more details if you need more info. What size are you building and which driver do you plan on using as that determines depth of channels. Keep us posted.
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Old 30th December 2012, 04:31 PM   #210
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Click the image to open in full size.

Cut up a box, taped it tight, dropped in some 3 inch FR drivers hooked it up and it sounds good.
For a free box.

I was thinking about trying out a Cornu spiral out of card board and dropping in these drivers.

Is a 24" or smaller size a safe way to go with these 3" drivers? They aren't too deep maybe 2.5".
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