Hi there.
I’ve seen horn loaded designs where there is a large mid range front loaded horn and inside the mouth of that horn there is a high frequency horn (loaded with a compression driver).
My question is, how is the mid range horn designed with an object in its mouth?
I know that wavelengths that are relatively large by comparison with the object will diffract around it and relatively small wavelengths will reflect (in free air, at least). And I realise if the crossover between the mid and high freq horns is at a suitable point, the frequencies that would reflect off the high freq horn would be cut out by the low pass filter on the mid.
However, I don’t know what happens when the object is surrounded by a horn.
Is the horn enlarged and/or shaped to compensate for the volume of the HF horn?
Or does the sound just ‘share’ the air in front of the horn and pass through as if it wasn’t there?
Or something else?
Thanks in advance.
I’ve seen horn loaded designs where there is a large mid range front loaded horn and inside the mouth of that horn there is a high frequency horn (loaded with a compression driver).
My question is, how is the mid range horn designed with an object in its mouth?
I know that wavelengths that are relatively large by comparison with the object will diffract around it and relatively small wavelengths will reflect (in free air, at least). And I realise if the crossover between the mid and high freq horns is at a suitable point, the frequencies that would reflect off the high freq horn would be cut out by the low pass filter on the mid.
However, I don’t know what happens when the object is surrounded by a horn.
Is the horn enlarged and/or shaped to compensate for the volume of the HF horn?
Or does the sound just ‘share’ the air in front of the horn and pass through as if it wasn’t there?
Or something else?
Thanks in advance.
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"Is the horn enlarged and/or shaped to compensate for the volume of the HF horn?" - I would assume this if the HF horn is large enough, but many mid-bass horns are compromised enough (too short, mouth too small) that it may not matter.
Lower frequencies may be interested in the overall expansion, but diverting the walls that way might not be liked by the higher frequencies.. nor might the obstacle.
Depends on the designer 😉
In my three-way nested Maltese horn system (circa 1992), the HF horn was enclosed in a box with a pyramid rear section which formed the phase plug for the two-part conical mid range horn.
Both horns used an identical expansion profile.
It may or may not be enlarged.
Looks like EAW's KF700 series mid horn continues to expand from start to finish:
Lots of diffraction effects in that mid horn, it really didn't "come together" until "Gunness Focusing" (temporal equalization using FIR DSP) reduced the artifacts.
The effects of path obstructions on sound waves are frequency dependent, the lower the frequency, the less effect.
Multiple entrant horns reduce most of the diffraction problems inherent with nested horns while reducing the cabinet volume.
Art
I think you're correct in guessing that the mid-range frequencies possibly do not interfere (much) with the treble horn inside, due to the larger wavelengths.
I don't think any adjustments are made to compensate for this effect as it seems to be 'allowed' by the laws of physics.
An example would be the JBL 2192/3/4 series that simply 'combines' the separately available 2392/3/4 mids and 2332/3/4 treble horns (using brackets) to get a family of 2-way 'co-axial' horns.
JBL 2192/3/4