KS Series: Cardioid Solutions

Subwoofers can be great for creating that big gut-punching concert sound

that a lot of artists and musicians want.

They can also help bring clarity to your PA

by taking on the burden of reproducing power-hungry low frequencies,

allowing the rest of the system to perform more efficiently.

However, subwoofers can also come with a few unwanted side-effects.

Unlike high frequencies, which are very directional, subwoofers radiate energy in all directions

around the entire enclosure.

This can lead to undesirable low-frequency build-up on the stage or DJ booth

and wasted energy around the sides and rear of the system,

which can often lead to issues like feedback or loss of intelligibility.

Additionally, if a subwoofer is placed near a wall or in a corner,

the reflections from these surfaces will most certainly lead to low-frequency cancellations.

This creates dips and holes in the low-end,

making the overall dispersion pattern inconsistent throughout the listening area;

leading to an unpleasant experience for the audience.

By utilizing what’s known as a cardioid subwoofer configuration,

you can “focus” the low-end radiation and give your entire system the directionality it needs,

cleaning up the low-frequency build-up on stage and keeping your PA system sounding musical

and intelligible for both the audience AND the performers.

Being able to direct the low-frequency can also be handy

when trying to keep your neighbors happy.

Traditional cardioid subwoofer deployments are created using an array of individual boxes.

In the simplest cardioid setup, you put two subs together either next to, or on top of each other,

with one of them facing backwards.

You heard that right.

Backwards.

Then, by using appropriate adjustments of the phase, delay, frequency, and gain alignment on both units,

the resulting pattern of the subwoofer array will become cardioid

and cancel out most of the low frequencies that are radiating toward the back.

How, you ask?

Because physics.

In this video we will demonstrate 3 ways to quickly and easily setup a cardioid configuration

using two KS118 active subwoofers.

One of the great features of the KS118 is the factory Cardioid Preset.

This Preset instantly takes care of all the adjustments needed

to set phase, delay, frequency and gain.

You don’t have to worry about all the math and the extra equipment it would take

to otherwise do it yourself.

The first deployment we’ll look at is a side-by-side configuration.

In this deployment, the two subs are placed side-by-side facing opposite directions.

Make the proper connections to your PA system

and then select the correct “Cardioid” preset on each of the KS118s.

On the front firing sub, select the CARDIOID FORWARD Preset

and on the rear-firing sub select CARDIOID REAR.

That’s it!

The presets will apply phase cancellation, correct gain and time alignment to the subwoofer array

and effectively create around 15 dB of low-frequency rejection behind it.

It’s pretty dramatic when you hear it in action.

If you have the vertical space available, you can use our second deployment

which is to stack the subs on top of one another, with the top cabinet pointed toward the audience,

for a an improved cardioid pattern.

In the last configuration, we’re going to position the subwoofers back-to-back.

This of course requires more horizontal depth, as the rear-firing sub will be directly behind

the front-firing one.

This setup will yield the best results out of the 3.

The time alignment in the Preset is perfectly optimized for this configuration,

which provides the highest amount of rejection in the back of the array.

Not only that

but the rejected energy in the back of the array will also help push more energy forward,

increasing the intensity of the low end towards the audience.

For smaller venues or events that may not require the might of two 18-inch subwoofers,

but could still benefit from directionality in the low end, we have the KS212C.

This is a best-in-class single enclosure cardioid subwoofer solution,

powered by a 3,600 Watt Class D amplifier and processed with the latest DSP technology.

It features two 12-inch long-excursion drivers, one forward and one rear-firing -

each arranged in a 6th order bandpass chamber.

These components all combine seamlessly to produce 15 dB less output at the rear of the enclosure.

If you’d like to know more about these KS Series subwoofers or how to set up cardioid arrays,

you can find further detailed information in our Application Guides and User Manuals

at qsc.com.

Thanks for watching.

We’ll see you next time.