JBL SDP-75 User Manual

Contents

JBL SDP-75 User Manual Manual pdf 144 page image

143ACOUSTICS CORRECTIONThe user can determine the type of filters for the automatic correction:• FIR + IIR: This is the default setting used by the Optimizer: Both IIR and FIR filters are used to work on the speakerresponses full range;• FIR only: No IIR filters are used, which means that the Optimizer will only work on the mid and high range of thespeaker responses. The low range will not be optimized;• IIR only: With this setting, both the automatic FIR and the FIR EQ are disabled. The Optimizer will only use IIR filtersto work on the low range. This setting could be used in specific cases where the user wants to be sure that no FIRfilters at all are applied.• High-pass filter frequency: Defines the cutoff frequency for the high-pass filter applied to all channels. Can bedisabled.CALIBRATION SETTINGS• Threshold for “resp” begin detect: The threshold below the peak level of the impulse that is taken into considerationto determine the onset of the response. -15 dB is the default value and works in most cases. However, a lowerthreshold is recommended in a room with a huge amount of early reflections where the peak might not be detectedcorrectly.OPTIMIZE ACCORDING TO L&R SPEAKERS SETTINGSThe Optimizer mode “According to L&R speakers” can be configured with specific settings:• Processing on L&R target (Default is IIR only): If the optimize mode is set to “Optimize according to L&R speakers”in the main settings tab, the Optimizer only uses IIR filters on the L&R speakers. This can be switched to “None” tomake sure the L&R speakers are not optimized at all.• Align L&R on target (Default is On): If this setting is on, the Optimizer applies filters on the Left & Right speakersusing their average response as target. If this setting is off, only the center and surround channels are optimized.• Optimizer Phase (Default is On): Determines whether the Optimizer should optimize the phase response of thespeakers or not when the L&R speaker mode is on.FIR AND IIR SETTINGSFIR stands for Finite Impulse Response. FIR filters are used to optimize amplitude and/or phase.IIR stands for Infinite Impulse Response. IIR filters are minimum phase filters used by the automatic compensation, inaddition to FIR, for the low frequencies.• FIR filter length (default is 100ms): Defines the length or number of taps of the FIR filter. The longer the FIR filter,the higher resolution the correction.• Number of IIR filters (default is 10): The number of IIR filters that will be used on every channel.• IIR filters minimal/maximal frequency (default is Automatic/150Hz): IIR filters will be positioned from the minfrequency up to the max frequency. The Automatic parameter uses the minimum frequency of the speakerbandwidth and the Low-freq auto transition bandwidth parameter to calculate the IIR filter minimal frequency.• Low-freq auto transition bandwidth (default is 1 octave): Determines the bandwidth of the auto transition. Theauto transition is the frequency range that separates the Optimized frequency range from the unfiltered frequencyrange in the low end. The upper boundary of this auto transition bandwidth is the minimal frequency of thespeakers bandwidth.• Room smoothing method (default is Modulus): For advanced users only.• Norm used for level_hp (!= align) (default is Room): For advanced users only.