Reflex Port Design

Genelec’s choice for vented, or reflex, enclosures dates back to the S30 model, the first Genelec product from 1978. Port performance has been improved and refined over the years with the aim to increase the woofer’s low frequency extension and sound pressure level capability to provide outstanding bass articulation and definition.

Both driver and vent contribute to the total radiation of a reflex enclosure. Most radiation comes from the driver, but at the vent-enclosure resonant frequency the driver displacement amplitude is small and most of the radiation comes out of the vent.

To minimize the air speed in the tube, the cross sectional area of the vent should be large. This in turn means that the vent tube has to be long which presents quite a design challenge.

The long, curved tube maximizes airflow so deep bass can be reproduced without compression. The reflex tube terminates with a wide flare located on the rear of the enclosure for obvious reasons, minimizing port noises and providing excellent bass articulation.

The curvature of the tube has also been carefully designed to minimize any audible noise, compression or distortion. The inner end of the tube has proper resistive termination to minimize once again audible chuffing noise and air turbulence.

Proper reflex port design allows also to significantly reduce the woofer’s displacement, improving the linear low frequency output capacity.