     ///   - masterGain: Master Gain (dB) ranges from -40 to 40 (Default: 0)
     ///
     public init(
-        _ input: AKNode?,
+        _ input: AKNode? = nil,
         threshold: Double = -20,
         headRoom: Double = 5,
         attackTime: Double = 0.001,

            self.releaseTime = releaseTime
            self.masterGain = masterGain

            inputGain = AKMixer(input)
            inputGain?.volume = 0
            mixer = AKMixer(inputGain)

            effectGain = AKMixer(input)

            au[kDynamicsProcessorParam_MasterGain] = masterGain
    }

    public var inputNode: AVAudioNode {
        return inputGain.avAudioNode
    }

    /// Function to start, play, or activate the node, all do the same thing
    open func start() {
        if isStopped {
