Hornresp input data for π midhorn with JBL 2012 driver

Hornresp simulated response for π midhorn with JBL 2012 driver

Measured response of π midhorn with JBL 2012 driver

If you're studying Hornresp, you might model some folded basshorns. The folds tend to attenuate HF, so cone breakup is rolled off. Because of that, measurements of folded horns tend to agree quite well with models. See the models of the 12π basshorn subwoofer, for example.

Is there any universal advantage to modeling in 1/8th space? If a design is intended for live SR, I'm thinking that 4xPi would be more realistic, as it would be the worst-case scenario for any venue setup.

I'm not up to trying a basshorn just yet! The Midhorn is challenge enough for a beginner, and the Input Parameter page still resembles a Greek crossword puzzle....

The rest of the fantasy was to coaxially mount the HF section inside the midhorn's mouth, using a pair of up-ended, trim'n'glue P.Audio PH2510 horns to create an unbroken vertical array to the next midhorn/high pak. Voila, vertical line array!

• 9π midbass horn

I was curious about the true upper cutoff of the 15" midbass horn, since HornResp tends to graph an earlier rolloff (or so I'm told). Is there a set ratio between HornResp and real-world measurements, or is the difference more design specific?

As for the differences between Hornresp models and measured response, the biggest difference is caused by cone breakup modes. Folded basshorns have close agreement with measurements because their folds and large front chambers attenuate output from breakup modes. Smaller midbass and midrange horns don't have these features, so output from breakup modes passes through them. In most cases, a crossover is used to prevent frequencies that would excite a speaker's breakup modes. In other cases, a speaker is chosen with damped and well behaved breakup modes to extend response.

Hornresp models assume rigid piston motion from the driver. When the cone enters breakup, regions of the cone vibrate independently of the rest of the cone. Ripples develop along its surface and each part acts like a smaller, lighter membrane with a stiff suspension between it and an adjacent node. So it sort of acts like an array of lightweight cones driving the horn. This creates extended response, but since the nodes are formed like ripples on a pond, their position moves with respect to frequency. Standing wave patterns develop along the cone, with some frequencies much louder than others. The net effect is that breakup mode output is usually pretty ragged and peaky. Sometimes it's usable, sometimes not.

• Midrange horn - Hornresp model and actual measurement