HPM, High Powerful Midrange Horn

HPM Horn – Dedicated Midrange Solution for Cone Drivers

The HPM horn is a dedicated midrange solution designed for direct-radiating cone drivers, meeting both high SPL requirements and constant directivity behavior.

To achieve this objective while maximizing output, we developed a direct-coupling interface between the cone driver and the horn. This design captures the wavefront directly at the surface of the cone, eliminating the air impedance mismatch that typically occurs between a conventional horn entrance and the radiating surface. Such mismatches can create response irregularities and SPL loss in the upper half of the horn’s operating range.

When paired with MX-Shape or X-Shape waveguides in 1.4" or 1.5" exit formats, the system delivers very high output in the 300 Hz to 1000 Hz range, with an on-demand constant-directivity pattern.

Unlike conventional compression-driver horns, HPM is specifically designed to operate with cone midrange and low-midrange drivers, typically ranging from 6" to 15" depending on the application.

For the kick-bass range, between subwoofers and the midrange section, we recommend a solution similar to the Peavey FH-1 kick horn enclosure.

The Coupling Interface

HPM applies the MX-Shape design philosophy to the midrange and low-midrange bands, extending X-Shape technology to cone-driver horn loading.

The HPM is supplied as a custom coupling interface, individually designed and simulated using FEA for each specific driver. A STEP file is provided for the wooden horn section that mates with the printed interface.

Because every application has unique requirements, HPM is offered as a custom solution and includes a consulting phase.

The 18Sound 10NMBA520 is recommended, although HPM can be designed for other cone midrange drivers.

Client Implementation Example

Below is an example of an implementation using a JBL CMCD midrange compression driver.

In this case, the direct-coupling throat component is not used, as the CMCD already incorporates an integrated phase plug.

Measurement

SPL

Typical response of the 1 m wide HPM with JBL CMCD (a midrange driver):

HPM technology can be used with all types of speaker cones; it does not define an absolute limit in SPL, which instead depends on the type of driver used and the horn following the throat.

The throat is a major contributor to the reactive loading effect, maximizing extension in relation to the driver and horn size.

Directivity