Dearest RobHello Camplo
Yes I listened to the file. You going for up close and personal. I got to listen to a pair of 4350's in a guys living room and it was a wall of sound years ago. Distance was good but to close together, cabinet separation could have been better. They were also set-up with the HF drivers inside which also limited the separation. You don't realize just how big they are until you see a pair in the flesh. Other than that dual 15 cinema boxes in a larger room at a DIY meet. Fun for sure!
As far listening distance on the 4350's in the manual I would say the recommendation was more subjective than anything else.
I am still not getting what the second driver is going to give you as far as direct sound. It's all supposition until you get them into your room and find a placement that works for them. I just hope your in close approach is not hobbled due to room issues. The larger the system the more difficult room placement is. Case in point those living room 4350's. Would have been much better in a larger space or a longer wall.
Rob
The point of adding another woofer would be to increase direct energy, that is all.
"The larger the system the more difficult room placement is." - This infamous topic....A larger, higher directivity system is easier to place in a room unless you are referring to a physical aspect.
Hello Camplo
Size being the main issue. How is your set-up high directivity?? You are not using a CD type horn and you are not matching DI at crossover. Your DI is changing as per your horn and I doubt you have any real directivity control at 300Hz. Have any polar plots on the horn??
Rob
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Directivity is a result of, mainly, radiation size....The horn is 33-36" wide......thats higher directivity than any 15" CD waveguide you could make. Larger woofers create more directivity than smaller woofers...I'm using nothing smaller than 15"s....considering dual 15"s for mids which raise directivity....When you listen to that recording of the 8" vs dual 15" the increase in direct energy has do with increase in radiation area, no less than, the higher directivity due to interaction and radiation size....The area of the horn mouth represents its radiation area size and the directivity follows suit.
The goal crossover point is beyond directivity of the horn and woofer....to me, thats a polar match well enough. Lets say the horn looses directivity strongly after 420hz and I decide to cross at 420hz.... The baffle width is basically right there with the horn width....A system is going to loose directivity at some point....so whats the big deal? The point is to avoid Banding, the point isn't to avoid loosing directivity, eventually, on the low end, thats inevitable
So the yeah you can make a 36" wide waveguide, but you'll never get the XO low enough to make it worth it lol, I guess thats not exactly true, if you desired higher directivity regardless of the XO point, a larger mouth is the main way to achieve it.
Still waiting on the horn, supposedly they are on the last steps...its been maybe 2 months longer than what they said it would take. You could simulate a tractrix horn in hornresp and see generally the polar pattern....The idea that I have "high direcitivity" is based around baffle widths and horn mouth and driver sizes. The type of horn im using (salmon family) has higher directivity in the HF than a constant directivity horn which seeks to lower directivity in the HF and match it with the rest of its spectrum in a manicured result. So for me 20khz till maybe 300hz will be emitted by 36" wide horn...the only way to raise directivity there would be to use a wider horn or a deeper one.....
The goal crossover point is beyond directivity of the horn and woofer....to me, thats a polar match well enough. Lets say the horn looses directivity strongly after 420hz and I decide to cross at 420hz.... The baffle width is basically right there with the horn width....A system is going to loose directivity at some point....so whats the big deal? The point is to avoid Banding, the point isn't to avoid loosing directivity, eventually, on the low end, thats inevitable
So the yeah you can make a 36" wide waveguide, but you'll never get the XO low enough to make it worth it lol, I guess thats not exactly true, if you desired higher directivity regardless of the XO point, a larger mouth is the main way to achieve it.
Still waiting on the horn, supposedly they are on the last steps...its been maybe 2 months longer than what they said it would take. You could simulate a tractrix horn in hornresp and see generally the polar pattern....The idea that I have "high direcitivity" is based around baffle widths and horn mouth and driver sizes. The type of horn im using (salmon family) has higher directivity in the HF than a constant directivity horn which seeks to lower directivity in the HF and match it with the rest of its spectrum in a manicured result. So for me 20khz till maybe 300hz will be emitted by 36" wide horn...the only way to raise directivity there would be to use a wider horn or a deeper one.....
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There is a difference here between direct radiators and horns as to how the size affects the directivity.
The larger dimension allows directivity control to a lower frequency in a horn but it says nothing of the amount of directivity which would be judged from the DI curve. The amount of directivity comes from the wall angle and curvature/depth.
And the wall angles of a horn are usually steeper and the depth is almost always deeper than a waveguide so whats that saying?
Among the commonly visited profiles of Horns and waveguides, the most common and influential factor is going to be Size, larger creating more or higher directivity. In order to increase any of the parameters you listed, on an existing horn you'll have to increase its....size.
Take a waveguide and increase the depth, you eventually get a horn do you not? Increasing depth increases directivity....starting at the HF side of the spectrum I believe.
Among the commonly visited profiles of Horns and waveguides, the most common and influential factor is going to be Size, larger creating more or higher directivity. In order to increase any of the parameters you listed, on an existing horn you'll have to increase its....size.
Take a waveguide and increase the depth, you eventually get a horn do you not? Increasing depth increases directivity....starting at the HF side of the spectrum I believe.
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You told me this a year or two back, that is, to match the horn mouth (or baffle horn is mounted on) and the baffle size. Its interesting how chasing a certain Horn cutoff placed my horn width approximately with my baffle width....If I had of purposely tried I could have correlated 15" with the baffle width....I serendipitously landed at 32" which is really close to 30"....I might be in the clouds, but, following the harmonics using woofer width, baffle/horn/waveguide width, horn cutoff and XO, sounds like a thing.
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If I change "the wall angle and curvature/depth." of the woofer cone.....Directivity doesn't change in the same way? Seems like it would have some correlation.
To start, this is just wrong. My intention is not to elaborate on how it's wrong, I'm just telling you that it is and now it's your task to figure out why. Try reading Marcel's thread - you can find the answer there.
The size controls the frequency where the device can have any directive control. You can have a very small device with a high DI and a very large device with a low DI. The amount of directivity is not controlled by the size of the mouth, the frequency of that directivity is.
While there are three basic parameters, mouth size, wall angle and depth, once you have fixed two the other is already decided. If you increase the depth and keep the wall angle the same the mouth has to increase. The amount of directivity will be the same but it will be held to a lower frequency because of the mouth size.
To me the most practical distinction between the terms waveguide and horn are that a waveguide has it's primary function dedicated to directivity control, and a horn has a purpose of increasing output. In between those two ends there is a middle ground.
"From 20khz to 300hz...emitting from one source, how would one create equal or more directivity, that is as practical as a large horn...??? More directivity being lf depth and higher di.."
I would look here for ideas. These are CD horns can go down to 350Hz with a phenolic driver 500Hz Ti
Rob
I would look here for ideas. These are CD horns can go down to 350Hz with a phenolic driver 500Hz Ti
Rob
I guess that does it lol....How in the world is this Horn holding directivity down to 200hz even, the measurements don't seem possible. Guess theres more for me to learn....a 31" wide horn can hold horizontal pattern down to 200hz....Claims a ~150degree horizontal beam width at 200hz. The horizontal beam width is smaller at 200hz in the more shallow horns...how? I guess that trade off is that it can't support playing that low so it doesn't matter.....
Good response Rob, how picky do I get to be? What If I say with no "diffraction slot".....and a shorter height than width, to minimize ctc...loads to 150hz....
So from 500hz to 1500hz the jbl horns have high DI...and then from 1500 to 20khz a tractrix horn with approximately the same width has high DI.
Good response Rob, how picky do I get to be? What If I say with no "diffraction slot".....and a shorter height than width, to minimize ctc...loads to 150hz....
So from 500hz to 1500hz the jbl horns have high DI...and then from 1500 to 20khz a tractrix horn with approximately the same width has high DI.
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