Constant Directivity Medium Waveguide, put your dedicated midrange driver in a waveguide

Why Medium Waveguide

The purpose of a waveguide, here a midrange waveguide, is not to significantly load the device but to control its radiation, for example by adding à little bit of Directivity Control extension or, even more important, to have an identical directivity when crossing it to a high frequency horn, like a X-Shape 25 with a 1" compression driver at the top.

When we want to cross horns between one another, we will not cut the high frequency horn where it begins to lose control, like we would do when crossing to some woofer in direct radiation, but higher, when it is still in full constant directivity behavior, so it’s the same for the midrange waveguide, we will cut it when it is in Constant Directivity behavior.

About a horn or waveguide on a midrange driver, we would use it in two cases :


This operation can be done with almost all mediums but there is a condition : the surround must be flat or a “pro” driver surround. Like PHL we talk but also:

And many others, all are already self closed mediums, the B&C have the lowest Fs and the best low end response.

Because we need to control the upper we need a tiny throat and to continue the driver shape, we will be completely some mm above the surround, as close as possible.

A precise nanometric reading of the membrane is needed with LIDAR or precise mechanical tools, each waveguide will be slightly different and tested in FEA.

The horn profile itself is not conventional, to have a constant directivity it has to undulate a little bit, it’s barrely not visible and needs an ultra precise FEA system to predict what will happen.

PHL 6.5" example

Here we use a 80x70° waveguide that can be cut with the X-Shape 25cm 80°, for long range application.

PHL waveguide
PHL waveguide back
PHL waveguide fixation

The rear chamber is 3L with a rear wave damping :

PHL waveguide
PHL waveguide back

Measurement on PHL 1130

Here is the SPL and the horizontal polar map, with on the right the possible integration with an X-Shape 25, the test WG is just a little bit too tiny.

We can see that we have to cut around 1850 hz to use the constant area of the medium horn, as we cut horn to horn and not horn to direct radiation woofer.

PHL-1130 polar
PHL waveguide presentation


Price and size:

As every medium will be almost unique, the price depends on size.

One of the mediums must be sent to us except for the listed PHL.