User manual SABINE ST-1000

[. . . ] The sound reverberates back and forth between the tile walls and floor. Just a touch of the volume fader fills the room with screeching feedback. Now move our sound system out to an open Fig. The speakers are well away from the microphone and there are no reflections, so now we can really crank up the system without a bit of feedback. [. . . ] That pulls out plenty of your program, too. On the other hand, you'll get considerably more net gain and much better sound quality if you use wide graphic EQ filters for tone control and insist on narrow filters for feedback control. 3. ) That's where parametric EQs come in. Parametric EQ In the quest for perfect sound, engineers developed very narrow tuned filters for controlling feedback points in auditoriums. In the early days of sound reinforcement, these filters were custom made to a specific frequency and width for a specific application. Now there are a number of commercially available parametric filter sets that allow engineers to dial in the width, center frequency and depth of the filter. The problem with parametrics is that they're expensive, they require a good deal of expertise and auxiliary equipment to tune properly, they require constant retuning whenever the room acoustics change, and they are far too slow and cumbersome for catching feedback that occurs during the program. Adaptive Parametric: The FBX Solution The Sabine FBX Feedback Exterminator® is the next step in the evolution of feedback control. The FBX is essentially a self-tuning parametric EQ. It constantly monitors the program, searching for tones that have the overtone signature of feedback. Once feedback occurs, the FBX automatically places a very narrow, constant-width filter directly on the feedback frequency and lowers it just deep enough to eliminate the ringing sound. If you insert too many filters in the system, you ference comes after the filter is placed. Fixed filters remain on the initially detected feedback tone - they do not move. These filters provide the initial maximum gain before feedback and are set automatically during setup. Dynamic filters can release and move to new feedback frequencies and are for A PA System was set up using a microphone, mixer, FBX, power amp and two speakers. The system's gain was raised until the FBX removed nine feedback points. Next the FBX was replaced with a graphic EQ. The EQ was adjusted while the system gain was raised to the same level achieved with the FBX. The frequency response curves of each device were then plotted. Fig. 1/3-Octave Graphic EQ will hear a degradation of the sound quality. If you set too few filters, you will not have enough mobility or gain. In this case, it is usually best to walk around the stage area until you find an area where feedback is a particular problem. [. . . ] 6: Typical Frequency Response Two overlapping EQ sliders pulled down 12 dB It is common to describe a filter's quality factor, or "Q, " as the center frequency of the filter divided by the filter width (in Hertz) measured at the -3dB point. Filters that have the same Q, or width, at the -3dB point regardless of the filter's cut or boost are called constant Q filters. Filters that get wider as the filter gets deeper are called proportional Q filters. There seems to be a new development in the audio industry. [. . . ]