PA top horn length verses elevated responce

[Music is life]

Since 100 Hz requires 33" of horn path a partial horn loading followed with a tuned reflex hum to reach down to the Sub is very enticing.
I've experimented with 19' to 22" limit of pathway and used the reflex tuning to compensate for the horn unloading below the 190 to 155 Hz limit of the horn.
All of my listening tests have been indoors so I'm sure that there would be a more significant drop in the bass outside with the cab placed some 5' or more up on a stand.

I'm thinking however that when different horn loaded cabs of different pathways results in the same bass responce down to 80 or 100 Hz as one might measure in half space, that the one with the longer pathway will perform the best when raised up on a stand. All other things being equal (and they never are) as far as this particular point is concerned the longer pathway is very desirable.

Not sure if that is true or why that might be true. Intuitively it seems that the 120Hz (for example) that is better horn assisted or loaded will drop off less when raised up from ground level.

I know that horn mouth area is in question as well. [And besides this many other factors such as midrange dispersion and midrange responce and so on but that is different consideration from my question on pathway verses raised up height responce].

[billfitzmaurice]

I know that horn mouth area is in question as well. [And besides this many other factors such as midrange dispersion and midrange responce and so on but that is different consideration from my question on pathway verses raised up height responce].How well a horn, or any cab for that matter, works when elevated is primarily a matter of the size of the radiating plane. The larger the plane the lower the baffle step frequency. The path length alone has little effect, other than as it affects Fc, though the geometry of the horn does affect dispersion in the upper end of the horn pass band.

[Music is life]

How well a horn, or any cab for that matter, works when elevated is primarily a matter of the size of the radiating plane. The larger the plane the lower the baffle step frequency. The path length alone has little effect, other than as it affects Fc, though the geometry of the horn does affect dispersion in the upper end of the horn pass band.
Thanks Bill.
If I understand these points:

The size of the horn mouth (surface area) is the primary determining factor of a horn loaded design as to how well it performs when elevated when all other factors are equal.

So then, the inevitable trade off between radiating plane, dispersion (horizontal), and upper frequency range which deal with horn path length, geometry and final size of the mouth.

2 horns or 2 cabs (verses 1 in a line array design) lowers the baffle step frequency by doubling the size of the radiating plane.


Conclusion (if I'm correct). Don't expect too much out of one single cab. Which is one of the many reasons why a well designed line array is so advantageous.

[billfitzmaurice]

Thanks Bill.
If I understand these points:

The size of the horn mouth (surface area) is the primary determining factor of a horn loaded design as to how well it performs when elevated when all other factors are equal.
.What I believe you were probably getting at is the difference between half-space and full-space loading. All speakers are measured in half-space, and when you lift a cab off the floor you lose that half-space loading. But you only lose it below the baffle step frequency, above that the radiation is directional and the cab is radiating into half space anyway even when elevated. The baffle step frequency is based on the one-wavelength dimension of the baffle in a direct radiator, of the mouth with a horn.

2 horns or 2 cabs (verses 1 in a line array design) lowers the baffle step frequency by doubling the size of the radiating plane.Only on the vertical plane, which is directly related to the vertical pattern control of line arrays, horn loaded or otherwise.

[Music is life]

What I believe you were probably getting at is the difference between half-space and full-space loading. All speakers are measured in half-space, and when you lift a cab off the floor you lose that half-space loading. But you only lose it below the baffle step frequency, above that the radiation is directional and the cab is radiating into half space anyway even when elevated. The baffle step frequency is based on the one-wavelength dimension of the baffle in a direct radiator, of the mouth with a horn.
Only on the vertical plane, which is directly related to the vertical pattern control of line arrays, horn loaded or otherwise.

Thanks for the responce Bill.

So it gets back to high sensitivity as the best offset for this phenomenon so that less lower range EQ is needed?
There's going to be some lower range loss no matter what when used elevated outdoors, right?

So the trend in commercial cabs to reduce cab size and count on processing in this lower range increases the demands for power and often additional cabs to compensate?

[billfitzmaurice]

So it gets back to high sensitivity as the best offset for this phenomenon so that less lower range EQ is needed? It always does.


There's going to be some lower range loss no matter what when used elevated outdoors, right? Yes


So the trend in commercial cabs to reduce cab size and count on processing in this lower range increases the demands for power and often additional cabs to compensate?It does. There remains no such thing as a free lunch.

[Music is life]

Thanks for sharing Bill.

Got some more terms to google :)