I am in need for a horn adapter between my Altec lansing 299 and Jabo 55 horn. The horns have 2" throat. I am aware off the 33710 adapter, and I may have to go for this but I could make this adapter my own since I have the opportunity at my job. Does anyone have some thoughts?
Two aluminum plates 2.2 inches apart with a 1.4:-2" cone inbetween is near-enough a 300Hz transition. For only 1.4:1 of diameter and 2:1 of area it is hardly worth banging-out an exponential, just make it smooth.
Would they be LeCleach or tractrix? You could use hornresp to design your adapter. (Apologies to PRR if you have this covered.)
Enter the current throat, mouth and length, check the angles to set the T factor and set the cutoff frequency. In other words, reverse engineer the horn type. Then you reduce the throat size and it will tell you how much longer the horn will be.
Enter the current throat, mouth and length, check the angles to set the T factor and set the cutoff frequency. In other words, reverse engineer the horn type. Then you reduce the throat size and it will tell you how much longer the horn will be.
If you change the horn length or throat size while keeping everything else steady, it will give you the information you need.
I wasn't thinking of the adapter designer. I haven't used it before.. but if you don't give it the information I've outlined above, then how can it do any better at extending the horn?
Which part do you have a problem with, can you get the throat size, mouth size, length, throat angle and mouth angle?
I wasn't thinking of the adapter designer. I haven't used it before.. but if you don't give it the information I've outlined above, then how can it do any better at extending the horn?
Which part do you have a problem with, can you get the throat size, mouth size, length, throat angle and mouth angle?
Throat is 50 mm, mouth is 530 mm and length is 330 mm. I would like to know what parameter expression this is in hornresp?
Once you know the horn type, you can extend it toward the throat.
Get into hornresp and put in your throat size, mouth size and length by setting the type to Hyp/Ex. Change the T factor until you see the same throat and mouth angle (view schematic) as your horn. If it does not work, try Exponential. It is probably not Tractrix or LeCleach, or if it is it's too truncated for hornresp to consider.
Get into hornresp and put in your throat size, mouth size and length by setting the type to Hyp/Ex. Change the T factor until you see the same throat and mouth angle (view schematic) as your horn. If it does not work, try Exponential. It is probably not Tractrix or LeCleach, or if it is it's too truncated for hornresp to consider.
Yes.
D1 is the diameter of the compression driver outlet and D2 is the diameter of the horn throat.
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Which parameters are you referring to? Those related to the horn, or those related to the throat adaptor?
There is conflicting information on the profile used in JABO KH-55 horn. In some places it is referred to as an exponential horn whereas in others it is considered to be a spherical wave or Kugelwellen type horn.
From the dimensions you give (throat diameter = 2 inch, mouth diameter = 53 cm and length = 33 cm) it seems that it is most likely to be an exponential horn with S1 = 20.27 cm2, S2 = 2206.18 cm2 and L12 (Exp) = 33.00 cm, meaning that F12 = 389.04 Hz and AT (throat entry half-angle) = 10.23 degrees.
Assuming that the outlet of the compression driver is 1 inch in diameter and that the half-angle of the outlet duct is 6 degrees, then the Throat Adaptor Designer tool parameter values become:
D1 = 25.4 mm (driver outlet diameter = 1 inch)
D2 = 50.8 mm (horn throat diameter = 2 inches)
A1 = 6 degrees (driver outlet half-angle)
A2 = 10.2 degrees (horn throat half-angle)
With the length of the adaptor calculated to be 89.2 mm, as shown in the attachment. Note that the adaptor profile data can be exported.
If the method suggested by AllenB is used and the 'extended horn' dimensions you show in Post #11 are applied, then the AT of the horn = 1.21 degrees and there will be a mis-match when connected to the compression driver (1.21 degrees versus 6 degrees). If the Hornresp Throat Adaptor Designer tool is used to design the transition piece, there will be no mis-match in the angles.
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Discovering this was of course to be the next step in the process. It also implies that there needs to be a compromise somewhere along the line to fit this driver to this horn. I recall Jean-Michel LeCleach once commenting on the versatility of his horn with regard to throat angles, and by inference, I feel this would apply to adapters.
Your adapter recommendation looks good.
"Assuming that the outlet of the compression driver is 1 inch in diameter and that the half-angle of the outlet duct is 6 degrees, then the Throat Adaptor Designer tool parameter values become:"
The outlet of the compression driver is 1.4 inch. Maybe this makes the mis-match.
On the other hand, I cannot thank you enough for the parameters being verified. I really appreciate it.
The outlet of the compression driver is 1.4 inch. Maybe this makes the mis-match.
On the other hand, I cannot thank you enough for the parameters being verified. I really appreciate it.
In that case, assuming that the outlet half-angle is still 6 degrees, the length of the adaptor piece would reduce to 50.6 mm.
The actual outlet half-angle should of course be used when designing a practical adaptor.
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David’s throat adapter is easy to use and should give you a very smooth transition.
Considering the profiles of many Altec throat adapters, this is certainly a step up.
Considering the profiles of many Altec throat adapters, this is certainly a step up.
For a mere 2:1 area ratio, a 10% different length is insignificant. The air waves do not go around with straightedges.