Modular Hourglass Port, The Ideal Speaker Vent

The Regular Port/Vent

The vent (or port) is designed to enhance bass response by leveraging its surface area and length. It increases the low-frequency output by functioning as a Helmholtz resonator.

Traditionally, this is achieved using a tube or a straight square or rectangular shape. However, the problem with tubes or other symmetrical forms lies in internal resonances caused by their shape, resistance due to abrupt changes at the entrance and exit, and dynamic compression that limits the acoustic pressure the vent can produce.

The Hourglass Vent

The first Hourglass vent was theorized and simulated in 2002 by three AES members: Alex Salvatti, Allan Devantier, and Doug J. Button.

This design aims to reduce vent noise generated by airflow, improve vent distortion caused by turbulence, and minimize dynamic compression by enhancing the coupling between the speaker box and the room. It achieves this through friction reduction along the port.

Dynamic vent compression is a phenomenon where, at higher volumes, the vent starts delivering diminishing energy despite the woofer output increasing.

While the overall shape of the Hourglass vent is advantageous—and even with a 12mm radius at the end—it still suffers from friction and an uneven velocity profile at the exit:

speaker vent

Additionally, its length cannot be easily adjusted to fine-tune the speaker’s performance.

The Modular Optimised Hourglass

Our design guarantees an uniform radiation velocity both at the vent’s exit and entrance:

speaker vent

It can be easily tuned using simple tube rings to match the desired length:

speaker vent

Each system consists of rear and front parts, which are designed and optimized using FEA (Finite Element Analysis) for each diameter. The assembly is designed to be mounted from the front of the speaker and secured in one step. This modularity allows for precise customization and ensures optimal performance.

Size System & Prices

Our modular Hourglass operates with tube tuning frequency equivalences to facilitate choice with port simulation software (VituixCAD).

Noted as “E” for PVC tubes of external diameters: 40/60/80/100/120 (other diameters available on demand). For example, an E80 is equivalent to a PVC tube with an 80mm diameter in tuning simulation software at the same length.

E80 Specifications

Next size coming soon