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Re: Midrange Horn [message #44391 is a reply to message #44366] Wed, 14 April 2004 11:46 Go to previous messageGo to next message
dwkurfma is currently offline  dwkurfma
Messages: 32
Registered: May 2009
Baron
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

Re: Midrange Horn [message #44394 is a reply to message #44391] Wed, 14 April 2004 18:00 Go to previous messageGo to next message
Adrian Mack is currently offline  Adrian Mack
Messages: 568
Registered: May 2009
Illuminati (1st Degree)
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.

Re: Midrange Horn - Thanks! n/t [message #44396 is a reply to message #44394] Wed, 14 April 2004 20:59 Go to previous messageGo to next message
dwkurfma is currently offline  dwkurfma
Messages: 32
Registered: May 2009
Baron
.

Re: Implementation [message #44407 is a reply to message #44371] Fri, 16 April 2004 11:00 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18669
Registered: January 2001
Illuminati (33rd Degree)
I just wrote a letter to Eminence, asking that they make the Alpha 10 front gaskets available as a separate item. This would make the perfect spacer, and it can be easily attached to the existing gasket with white glue or just put in place when the driver is bolted to the mounting plate. If they'll sell them, I'll include the spacer gasket with every horn.

Re: Implementation [message #44408 is a reply to message #44407] Fri, 16 April 2004 18:30 Go to previous messageGo to next message
Adrian Mack is currently offline  Adrian Mack
Messages: 568
Registered: May 2009
Illuminati (1st Degree)
Good idea. So its the same gasket thats on the driver, having essentially two of them? How thick are the gaskets/spacer on the Alpha 10 by the way?

Re: Implementation [message #44409 is a reply to message #44408] Fri, 16 April 2004 18:39 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18669
Registered: January 2001
Illuminati (33rd Degree)
Gonna have to do it on the Alpha 10 too. I'm assuming it's the same gasket, which is about 1/4" thick.

Re: eight π [message #44701 is a reply to message #44370] Wed, 02 June 2004 22:11 Go to previous messageGo to next message
wasteh202 is currently offline  wasteh202
Messages: 137
Registered: May 2009
Master
Wayne

Are you sending out the plans for this model 8 speaker yet ?

...and are you packaging kits for this model ?

Thanks, Rodney

Re: eight π [message #44741 is a reply to message #44701] Fri, 11 June 2004 09:42 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18669
Registered: January 2001
Illuminati (33rd Degree)
We have everything for kits in stock except one of the coils. I ordered a bunch of them and expected them middle of last month, so we're a couple weeks later than I had hoped. But we're almost there, and we have the kits listed on the π Speakers shopping cart.


7PI midrange horn angle [message #62023 is a reply to message #44366] Tue, 09 March 2010 15:01 Go to previous messageGo to next message
hornT is currently offline  hornT
Messages: 6
Registered: March 2010
Location: Denmark
Esquire
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?
Re: 7PI midrange directivity [message #62024 is a reply to message #62023] Tue, 09 March 2010 15:20 Go to previous messageGo to previous message
Wayne Parham is currently offline  Wayne Parham
Messages: 18669
Registered: January 2001
Illuminati (33rd Degree)

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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