/// <summary>
/// Bandpass EQ curve, recommended for stage subwoofers.
/// </summary>
/// <param name="lowFreq">Low frequency (highpass) cutoff knee</param>
/// <param name="highFreq">High frequency (lowpass) cutoff knee</param>
/// <param name="sampleRate">Sample rate of the system to be EQ'd</param>
/// <param name="resolution">Sample resolution for <see cref="this[double]"/>, must be a power of 2</param>
/// <param name="q">Q-factor of the filter</param>
/// <param name="order">Each order increases the slope with 6 dB/octave</param>
/// <param name="gain">Filter gain</param>
public Bandpass(double lowFreq, double highFreq, int sampleRate, int resolution, double q = QFactor.reference, int order = 1,
double gain = 6)
{
positioner = resolution * 2.0 / sampleRate;
float[] reference = SweepGenerator.Exponential(20, sampleRate * .5f, resolution * 2, sampleRate),
response = reference.FastClone();
BandpassFlat filter = new BandpassFlat(lowFreq, highFreq, sampleRate, q, order);
filter.Process(response);
spectrum = Measurements.GetSpectrum(Measurements.GetFrequencyResponse(reference, response));
GraphUtils.ConvertToDecibels(spectrum);
this.gain = gain;
}