User manual BSS FCS966

[. . . ] FCS 966 User Manual 1 V 1. 0 BV/JMK 30 April 1998 An example of this equipment has been tested and found to comply with the following European and international Standards for Electromagnetic Compatibility and Electrical Safety: Radiated Emissions (EU): EN55013 RF Immunity (EU): EN50082/1 Mains Disturbance (EU): EN61000/3/2 Electrical Safety (EU): EN60065 Radiated Emissions (USA): FCC part 15 Class B (1990) Associated Equipment (1992) RF Immunity, Fast Transients ESD (1995) (1993) IMPORTANT SAFETY INFORMATION DO NOT REMOVE COVERS. NO USER SERVICEABLE PARTS INSIDE, REFER SERVICING TO QUALIFIED SERVICE PERSONNEL. IT SHOULD NOT BE NECESSARY TO REMOVE ANY PROTECTIVE EARTH OR SIGNAL CABLE SHIELD CONNECTIONS TO PREVENT GROUND LOOPS. ANY SUCH DISCONNECTIONS ARE OUTSIDE THE RECOMMENDED PRACTISE OF BSS AUDIO AND WILL RENDER ANY EMC OR SAFETY CERTIFICATION VOID. For continued compliance with international EMC legislation ensure that all input and output cables are wired with the cable screen connected to Pin 1 of the XLR connectors and/or the jack plug sleeve. [. . . ] When the slider is in the central position it is effectively out of circuit. 17 General guide to equalising 7. 0 General guide to equalisers 7. 1 What is a graphic? The graphic equaliser is one of the most common pieces of signal processing equipment. It finds uses both in recording environments and live performance, as well as sound reinforcement and noise pollution control. The graphic equaliser is a very powerful tool, and as with all powerful devices caution should be exercised or problems will occur. A graphic equaliser operates by splitting the audio signal into a number of individual bands; in the case of the FCS 966, 30 bands. As each of the ten musical octaves that make up the audio spectrum is split into 3 bands, the FCS 966 is termed a `third octave equaliser'. The frequency or pitch of each frequency band is printed on the front panel, between the rows of sliders. Each frequency slider allows signals that fall in that band to be individually raised (boosted) or lowered (cut) in level. The maximum amount of boost or cut is indicated adjacent to the sliders and in the case of the FCS 966 is +/-15dB or 30dB overall. 30dB corresponds to a change in level of approximately 32 times. If the slider is in the centre, zero position, signals in that band are unaffected. 7. 2 How do I use it? As there is individual control of each frequency band, the signal can have its tonal quality and balance totally altered. As a general rule the sliders on the left 20% of the graphic have affect on the bass sound, with the right 20% affecting the treble. The sliders towards the centre, around 1kHz, affect the presence or midrange. Fig 7. 1 The effect of sliders on different instruments 18 Figure 7. 1 shows very approximately the sliders that have most effect on some common instruments - having an effect is related to the harmonic richness of the sound. A flute for example, generating relatively pure tones, will only have energy in a small number of bands at a given time, whereas a guitar has harmonics covering most bands. When applied to the guitar, the equaliser will be capable of completely changing the sound. A graphic equaliser may be used for both creative and corrective use. Both these uses can apply to whole sound systems or individual instruments. When used creatively, it may be set to change the timbre of an instrument and so alter its character. Used in a corrective manner, maybe on the same instrument, it can be used to remove a resonance that is making the instrument sound muddy or shrill. Graphic equalisers are also used extensively to treat the human voice and, by 'flattening' irregularities, can improve the perceived quality of inexperienced performers. Generally creative uses utilise gradual changes with small differences in position between adjacent sliders. Radical corrective surgery is usually indicated by larger adjustments to individual sliders, thereby treating the problem whilst leaving all other areas unaffected. See section 8 for some examples. 7. 3 What does constant Q mean? The `Q' of a filter is a technical term which corresponds to the measurement of its width, hence the term constant Q implies that as a slider is moved, the Q or width of the applied filter stays the same - refer to figure 7. 2. Fig 7. 2 difference between constant and non-constant Q sliders If the width varies with slider position, as it does with non constant Q equalisers, accurately summing the result from a number of sliders will be impossible except at one position, the position when the Q or width equals the space between two adjacent bands. [. . . ] Adjusting the LF contour control provides a simple solution. Using the HF Filter in conjunction with LF contour provides a very powerful combination for adding 'weight' to small systems without causing sub-sonic overloads. 8. 6 Use for the HF contour Like the LF contour control, HF contour should be regarded as a way of musically changing the tonal balance of the FCS 966. A common problem encountered in live sound applications is the drop in treble level that occurs when an audience is present. Heat and humidity can also alter the level of treble during a performance. Advancing the HF contour control is a unique and ideal way of dealing with this effect. 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