JBL VTX Series User Manual

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JBL VTX Series User Manual Manual pdf 29 page image

29VTX A 8 | User ManualSince the factory preset cannot account for all variables and array configurations, user adjustment of certain DSP parameters is neces-sary to achieve the desired tonal balance for a given array and application. The LF response of any VTX line array system can be easilyadjusted using the Array Size Compensation Filter in the JBL Line Array Control Panel. The Array Size Compensation Filter was specif-ically designed to compensate for LF/MF buildup with a single, adjustable parameter. Lowering the gain value of this filter will shift theLF rising point lower in frequency — similar to how shortening the length of an array works.Frequency response of a 12-cabinet A8 arrayFrequency response of a 12-cabinet A8 array using the80Hz preset20 100 1000 10000 20000Frequency (Hz)-20-1001020SPL (dB)11 - FREQUENCY RESPONSEThe frequency response of a line array is determined by many factors, including the array size (number of boxes), array curvature (box-to-box angles) and the listening distance. JBL factory presets are designed to create a well-balanced tonal starting point for given arrayconditions. For example, the standard VTX A8 array presets are designed to work optimally with array sizes between 8 - 12 cabinetsand equal impact spacing for a flat listening plane. An array with these parameters will generate a flat frequency response in the HFregion with a gradual rise in LF energy. The frequency point where the response starts rising depends on the array parameters men-tioned above. A relatively short array will start rising lower in frequency, and a longer array will start rising higher in frequency. Below arefrequency response examples of A8 arrays using the standard VTX A8 presets and no additional equalization/correction (flat).20 100 1000 10000 20000Frequency (Hz)-20-1001020SPL (dB)Frequency response of a 12-cabinet A8 arrayFrequency response of an 8-cabinet A8 arrayFrequency response of a 6-cabinet A8 arrayFrequency response of a 4-cabinet A8 arrayExample 1 : A8 Frequency response vs number of cabinetsExample 2: Standard preset vs 80 preset