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2 Ways to Fight Feedback: X-FDBK vs. Primary Source Expander

Dec 07, 2016

These two plugins will get you the loudest, cleanest FOH and monitor mixes – but each has its own advantages. Learn when to use each and for which purposes.

While both X-FDBK and Primary Source Expander (PSE) help prevent feedback, they do it in very different ways and therefore each of them is meant for different uses.

Let's first understand the main differences between how the two plugins operate.

It basically boils down to the difference between controlling frequencies and controlling gain levels:

  • X-FDBK identifies the precise frequencies that cause feedback and surgically cuts them.
  • PSE automatically attenuates the gain level between musical phrases in a predetermined amount according to a set threshold. By reducing noise and mic bleed down between phrases, it also reduces sensitivity to feedback.

Because of these differences, each plugin is good for different purposes:



Use X-FDBK when:

  1. You have a singer who cups the microphone and causes feedback constantly while singing.

    X-FDBK will cut the offending feedback frequencies at all times, even while the singer is singing. By comparison, PSE will attenuate the gain and help prevent noise and feedback only while the singer is not singing.

  2. You have an instrument with long sustain, for example piano.

    X-FDBK will accommodate the instrument’s natural dynamics, feel and decay time, whereas PSE might cut off the sustain on instruments with long natural decay such as the piano.
Primary Source Expander

Primary Source Expander

Use PSE when:

  1. You have a singer who moves a lot and goes past the PA line.

    PSE will prevent the PA from feeding back whenever the singer is not singing, by automatically lowering the mic gain between sung phrases.

  2. You want to reduce stage noise bleeding through your mics.

    By attenuating the gain of your open microphones between musical phrases, PSE makes sure you don’t get unwanted sounds coming through the microphones when they are idle, for example, when the singer is not singing through the mic. (X-FDBK is not designed to fight noise bleed, only to eliminate feedback.)

Here are the differences between the two plugins at a glance:

Method of operationCuts frequenciesAttenuates gain
Reduces stage bleedNoYes
Good for instruments with long sustain (such as piano)YesNo
Affects the tonality/EQ of the sourceYesNo
Placement in the signal chainIndividual channels, auxes, master channelIndividual channels

What if I want to use both plugins together?

You can definitely do that.

  • First use X-FDBK to ring out your monitors and PA. X-FDBK will usually be inserted on your aux when ringing out monitors and on your master buss when ringing out the PA.
  • Then insert PSE on the relevant channel and adjust the threshold and range in order to reduce stage bleed between phrases in that channel.

Have a great show!

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