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snowflake View Drop Down
Old Croc
Old Croc


Joined: 29 December 2004
Location: Bristol
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Points: 2587 		Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Topic: B2F
    Posted: 02 July 2020 at 1:56pm
obviously I have taken inspiration from somewhere else but switched things round - hence B2F

driver magnets don't actually touch because they are offset - one against the top of the cabinet, the other against the bottom so the vent clears the opposite magnet. for some neo drivers the magnets clear each other completely meaning very deep drivers can be used.

rear chamber vents are optional - will design a plate to bolt over to close them off when not wanted. still working on access hatch(es) - will probably go for a well-braced wooden rear door with connector dish built into it.
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monkeypuzzle View Drop Down
Young Croc
Young Croc


Joined: 25 January 2005
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Points: 737 		Post Options Post Options   Thanks (1) Thanks(1)   Quote monkeypuzzle Quote  Post ReplyReply Direct Link To This Post Posted: 02 July 2020 at 4:13pm
Looks very interesting, rather than having a plate that covers the front ports as an optional, hows about a plate that is either blank or ported that swaps out in that front piece. This would allow access to do up those very hard to reach driver bolts.
blah blah blah blah blah......
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madboffin View Drop Down
Young Croc
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Joined: 03 July 2009
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Points: 1441 		Post Options Post Options   Thanks (0) Thanks(0)   Quote madboffin Quote  Post ReplyReply Direct Link To This Post Posted: 02 July 2020 at 5:48pm
I like that.
Go on then, take a leaf out of Doober's book and knock up a prototype!
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snowflake View Drop Down
Old Croc
Old Croc


Joined: 29 December 2004
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Points: 2587 		Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 02 July 2020 at 9:10pm
Originally posted by monkeypuzzle monkeypuzzle wrote:

Looks very interesting, rather than having a plate that covers the front ports as an optional, hows about a plate that is either blank or ported that swaps out in that front piece. This would allow access to do up those very hard to reach driver bolts.


yeah might do that as it is going to be awkward. I'm going to make the whole baffle on which the driver is mounted removable, so I can put the mounting points where they are covenient to some degree.
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snowflake View Drop Down
Old Croc
Old Croc


Joined: 29 December 2004
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Points: 2587 		Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 08 July 2020 at 1:18pm
I can get this driver to fit:


can't quite get this one to fit but it seems to have been taken off the BMS website anyway:

http://www.loudspeakerdatabase.com/BMS/15S430v%C2%B2
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snowflake View Drop Down
Old Croc
Old Croc


Joined: 29 December 2004
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Points: 2587 		Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 08 July 2020 at 1:23pm
few more details left and then try to make a sensible cutlist




Edited by snowflake - 08 July 2020 at 1:24pm
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odc04r View Drop Down
Old Croc
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Points: 5483 		Post Options Post Options   Thanks (0) Thanks(0)   Quote odc04r Quote  Post ReplyReply Direct Link To This Post Posted: 08 July 2020 at 3:22pm
Looks interesting, does resemble a certain design a little. How did you model it, port assisted FLH or variant on a bandpass horn?
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snowflake View Drop Down
Old Croc
Old Croc


Joined: 29 December 2004
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Points: 2587 		Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 08 July 2020 at 6:54pm
Originally posted by odc04r odc04r wrote:

Looks interesting, does resemble a certain design a little. How did you model it, port assisted FLH or variant on a bandpass horn?


modelled in hornresp as FLH with ported rear chamber and a path length difference
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snowflake View Drop Down
Old Croc
Old Croc


Joined: 29 December 2004
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Points: 2587 		Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 08 July 2020 at 7:03pm
one thing I'm really not sure about is the braces in the mouth. I've drawn them at an angle between the sidewall and the opposite horn flare. but if you assume the wavefront travels down each wall of the speaker at the same speed and is perpendicular to each wall, then the wavefront must be slightly S shaped as it approaches the mouth and the braces are at the wrong angle to allow smooth airflow past them. might replace with 6mm steel bar to remove the issue completely. once it gets to the mouth the path length differences should give quite a nicely curved wavefront coming out the front of the box.


Edited by snowflake - 08 July 2020 at 7:04pm
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odc04r View Drop Down
Old Croc
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Points: 5483 		Post Options Post Options   Thanks (0) Thanks(0)   Quote odc04r Quote  Post ReplyReply Direct Link To This Post Posted: 08 July 2020 at 9:19pm
Or just grind down the rear flat to make a wedge if you were worried. You'd imagine it probably wouldn't make a noticeable difference given wavelengths involved, but who can say till it is tried.
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snowflake View Drop Down
Old Croc
Old Croc


Joined: 29 December 2004
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Points: 2587 		Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 08 July 2020 at 9:46pm
I mean the wavefront must be something like this. so hitting that brace almost 90deg off from what you would want
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Young Croc
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Joined: 30 March 2011
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Points: 915 		Post Options Post Options   Thanks (0) Thanks(0)   Quote smoore Quote  Post ReplyReply Direct Link To This Post Posted: 08 July 2020 at 9:53pm
How do you add a path length difference in hornresp between port and horn?
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