This is the first in a multi-part series. Additional segments are available here.

In general, we say that a speaker, or a group of speakers, radiates with a cardioid pattern when it radiates more energy forward than it does backward.

Strictly speaking, however, a cardioid pattern is heart shaped (hence the name) and is represented mathematically by the equation ρ = (1 + cos σ), where σ represents the horizontal angle.

Setting up subwoofers such that they radiate this way is a relatively simple task.

One just needs to know what steps to follow as well as how to use one of several measurement systems that provide a transfer function mode.

There exist several cardioid subwoofer configurations, but the method to be followed, as described here, is always the same.

This article does not intend to assess the various configurations, but only to show the basic procedures and ease the learning process.

The user should choose the most appropriate configuration for the specific application needs.

Throughout this article we’ll see measurements performed using SATLive. Phase curves are shown on the bottom part of the image, while the magnitude frequency response will be at the top of the image.

What applications is a cardioid subwoofer configuration appropriate for?

There are several situations where cardioid configurations can be useful.

For instance, when using conventional subwoofers with a wall behind them, the back wave will bounce back and cancellations will happen at the front (let’s not forget that subwoofers radiate in all directions).

In other words, the reflected wave from the back wall will arrive at a different time with respect to the direct wave, i.e., there will be a phase difference between them that will create destructive interference.

A cardioid configuration will radiate very little pressure backward, hence minimizing that effect.

When using a L-R subwoofer configuration, especially on a small stage or at an indoor venue, we can help the monitor mixing engineer do his job by “cleaning” subwoofer frequencies, which can mask instruments, off the stage.

With a cardioid configuration, clarity will be gained on stage.

A common subwoofer configuration is to group all the units together in front of the centre of the stage, forming a single line. Subwoofers may be fed a stereo signal or the output from a mixer’s aux group.

This arrangement has pros, but also a few cons: since subwoofers radiate in all directions, there will be a pressure maximum on the stage, behind the subwoofers.

This can end up being annoying for some musicians (not for all), as well as making the job of the stage mixing engineer more complicated, as we have mentioned before. A solution would be to make the subwoofers radiate as little as possible towards the back by using a cardioid configuration.

When speaking of cardioid configurations, users will often complain that they need to add cabinets to the system “just” to produce “less sound”.

For instance, some configurations require twice the number of cabinets that would be normally used.

Page 1 of 2
1 2 >  Next