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Porn Horn

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nuggets View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote nuggets Quote  Post ReplyReply Direct Link To This Post Topic: Porn Horn
    Posted: 03 May 2005 at 12:00pm
Hi, thinking of building MT122s with the porn horns. Would there be any difference in placing the two mids on the bottom of the cabinet and the top on top? Also do the porn horns make much of a difference compared with the original design???
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Jez_Ultra View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Jez_Ultra Quote  Post ReplyReply Direct Link To This Post Posted: 03 May 2005 at 1:44pm

The main benefit of the Porn Horn is the inclusion of the phase plug, which simply means that you'll be able able to cross over into the compression driver much higher - giving you a much cleaner sound. 

 

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james folkes View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote james folkes Quote  Post ReplyReply Direct Link To This Post Posted: 03 May 2005 at 6:07pm
as i understand it the horn flares of the two mt122 flares are designed
such that with the separation of the compression driver there is minimal
lobing effect between them. furthermore i think the cabinet trapezoid
angle is also matched to the horn flare so that they can be arrayed.

having the compression driver in the middle also presents more of a point
source in the mid high frequencies, but makes them more suited to
sitting on a tall bass stack to aid projection. balancing these factors with
the dispersion characteristics of the porns is i think the issue.

there is a thread showing a trapezoidal cabinet construction method for
the porn horn with a single compression driver entitled "porn addick" in
the slightly older bits of the new projects forum. it goes a bit off-topic as
you will see and unfortunately dispersion is not discussed.

james.
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nuggets View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote nuggets Quote  Post ReplyReply Direct Link To This Post Posted: 08 May 2005 at 1:50pm

Had a look at that porn addick thread: http://www.speakerplans.com/forum/forum_posts.asp?TID=1620&a mp;a mp;KW=porn+addick

It says 2 X 12" horns but only has one in the design. Just add another to it? To the top of the cabinet or botton???

What's 'lobing'?



Edited by nuggets
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james folkes View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote james folkes Quote  Post ReplyReply Direct Link To This Post Posted: 09 May 2005 at 5:50am
lobing is the result of overlap from multiple sources which don't array
happily. the trapezoidal walls of the mt122 cab mate with the vertical
flare components to ensure that as you wander across the soundfield the
level is mostly uniform, minimising the effects of destructive wave
superposition.

the separation of the two mid components using the compression driver
ensures the same behaviour between these two horns, where the effect
would be more pronounced as you changed height or distance away from
the stack.

the effect can be very noticeable at low mid frequencies where there are
distict 'quiet spots' for some notes infront of the stack. this is my
understanding and experience of the subject. as for predicting the
dispersion patterns and the constructive and destructive superposition of
the porns, that's so far out of my league it's not even funny. nevertheless
it will be crucial in determining how to best locate the porns in your
boxes, so keep asking. it does matter, and someone will know.

james.
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tendril View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tendril Quote  Post ReplyReply Direct Link To This Post Posted: 28 May 2005 at 12:26pm
Why not make 1 with top and mid and 1 with just the mid. Then you could change the setup depending on how high your bass stack is, with the single porn either on top la MT122 or underneath for use on a shorter stack.
Tendril

A mistake is a mistake only if one learns nothing from it.
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