| Re: Midrange Horn [message #44391 is a reply to message #44366] |
Wed, 14 April 2004 11:46   |
dwkurfma
Messages: 32
Registered: May 2009
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Baron |
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Just a flat mounting surface, right? Any special surface treatments appropriate? (felt, foam, etc.) Round over the throat entrance with a router help any? Without the inductor could the same basic unit be used with JBL 2123 or 2118 do you think? Dan
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| Re: Midrange Horn [message #44394 is a reply to message #44391] |
Wed, 14 April 2004 18:00 |
Adrian Mack
Messages: 568
Registered: May 2009
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Illuminati (1st Degree) |
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Routing the throat entrance so that its rounded wont do anything. Flares which terminate sharply at the mouth typically suffer mouth diffraction more than ones which dont. Just like a speaker box, really. On a tractrix flare, the added flare at the end of the mouth serves to limit diffraction. On other flares which dont have this extra rounded bit, some people put felt or some other damping material around the edges of the mouth to reduce diffraction. Dont put any absorbing materials inside the throat or near the throat entrance or higher frequencies will be attenuated severly. I'd add a mounting ring or route out a groove where the edge of the cone/surround meets up with the mounting plate to prevent it from slapping against it at high levels.
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| Re: eight π [message #44701 is a reply to message #44370] |
Wed, 02 June 2004 22:11 |
wasteh202
Messages: 137
Registered: May 2009
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Master |
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Wayne Are you sending out the plans for this model 8 speaker yet ? ...and are you packaging kits for this model ? Thanks, Rodney
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| 7PI midrange horn angle [message #62023 is a reply to message #44366] |
Tue, 09 March 2010 15:01 |
hornT
Messages: 6
Registered: March 2010
Location: Denmark
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Esquire |
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Just wandering about the angles of the flare on the 7PI mid horn. Theoretically they are supposed to be 90x40 but mine are only ~83x29
And according to the drawings 29x83 is correct. Is there a catch. Its my first homebrewed midhorn so maybe I messed things up?
Does flat frequency response really exist?
- and is it equal to perfect sound?
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| Re: 7PI midrange directivity [message #62024 is a reply to message #62023] |
Tue, 09 March 2010 15:20 |
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Wayne Parham
Messages: 18783
Registered: January 2001
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Illuminati (33rd Degree) |
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The wall angles aren't exactly 90°x40°, more like 85°x30°. Those angles are what set the pattern up high, and the (corner) room boundaries are what set it down low.
To give a little more description of of the pattern, the flare wall angle sets the radiating angle at frequencies where mouth dimension is greater than about 4/3λ. Below that frequency, the pattern narrows briefly and then begins to widen. By about 3/4λ, it is about double the flare wall angle.
To put this into perspective where the midhorn is concerned, it does a pretty good job of setting the pattern in the horizontal, having control down to just a few hundred Hertz. Below that, the corner placement provides assist, with the room walls setting the pattern all the way down to the Schroeder frequency, where room modes take over. Where the pattern width would double in freespace at 400Hz or so, the room's walls confine the beamwidth and limit the radiating angle. In a sense, the corner itself acts as an extension to the horn.
The vertical is a different situation, and the wall angle doesn't really set the pattern. The vertical pattern is taller than the flare wall angle, more or less collapsing through the entire band up to the crossover region, where it narrows to approximate the flare. This then limits the amount of energy at large vertical angles in the crossover band, which helps reduce null-forming interactions. But the point is that the horn doesn't really set the vertical pattern until nearly the crossover frequency. It isn't large enough.
It is important to understand that vertical directivity of the individual sound sources is modified when stacking other sound sources to form a loudspeaker system. In a sense, vertical position is more important than the source's vertical pattern because when sources are stacked, the interactions form lobes and nulls. See my reply in your other thread:
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