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Фрагмент инструкции
In general, large rooms benyou estimate the predominate feedback frequency efit from some low frequency shelf roll-off, high frequency to occur. shelf boost, and attenuation of ring mode frequencies by the parametric filters. 4. Push in the filter’s EQ switch and increase its level control by about +6 dB. Now “sweep” the 6.6 Small Room Equalization frequency around where you have estimated the feedback frequency until feedback occurs. Once Small rooms need less equalization than large you have induced the feedback by boosting its ones. However, with reflective surfaces so close together frequency, quickly turn down the filter’s level it is more likely to encounter high frequency feedback control to about -6 dB to suppress or “notch out” problems. Finding and critically notching out these of- the feedback frequency. fending “hot spots” is precisely what the PQX equalizer does best. Use the narrowest possible bandwidth, and as 5. Again slowly increase the master level at the always, avoid over-equalization. mixer until feedback is heard. If a new feedback frequency is heard, then repeat step 3 to find and 7. THEORY suppress the new frequency. If the original feedback frequency is still heard, then adjust the first The heart of the PQX equalizers is a unique filter’s level even lower. The bandwidth control bandpass filter circuit. Basically a “state-variable” type, this may be adjusted full clockwise to produce a very filter is trimmed and optimized to provide excellent transient sharp notch so that a severe feedback frequency response and a wide range of frequency and bandwidth ad- can be attenuated by as much as 15 dB without justment. Each filter can be tuned over a 100:1 frequency degrading the frequency response with noticeable range (about 6.6 octaves) and a 70:1 bandwidth range with notches. Note: Very sharp bandwidth lowers the no more than a 2 dB amplitude error at center frequency. At maximum equalizer input level because of the its sharpest setting, the filter has a “Q” of about 35 and genhigh filter gain necessary to obtain such a narerates a response curve with 3 dB points only 1/20 octave row bandwidth. Only use bandwidth control full apart, making feedback control possible with no audible side CW (.05 Octave) in severe cases. effects. Each filter is placed in the feedback loop of a summing amplifier to produce the desired frequency response. 6. Continue this iterative process of increasing Since a separate summing amplifier is used for each band, the mixer’s master level and finding, then sup-no interaction between bands occurs. pressing feedback frequencies until a desired sound system gain-before-feedback level has been achieved. 6.4 Console Channel Equalization Many mixing consoles provide only simple equalization for individual channels. If your console has channel inserts, you can patch your equalizer into a channel that is used for something important, and use it to tailor the sound of this channel exactly the way you want. PQX Block Diagram - ++ - CLIP DETECTOR PEAK HIGH 20-20K 20-20K 20-20K 20-20K 20-20K FILTER FILTER FILTER FILTER FILTER PAR. PAR. PAR. PAR. PAR. IN IN IN IN IN IN IN EQ EQ EQ EQ EQ EQ EQ Q Q Q Q Q FRFRFRFRFRFRFR +/-+/-+/-+/-+/-+/-+/- FILTER SHELF SHELF LOW OUTPUT IN OUT EQ GAIN INPUT BALANCED Operating Manual - PQX 571 and PQX 572 Parametric Equalizer 8. TROUBLESHOOTING TIPS 8.1 No Output Check AC power - is the Power LED on? Check in/out connections -are they reversed? Are you sure you have an input signal? 8.2 Eq Controls Do Nothing Is the master EQ in/out switch in? Maybe the bandwidth setting is too sharp to produce an audible change. The center frequency and bandwidth controls do not have an effect if the level control is set at “0”, or if the in/out switches are switched out. 8.3 Clip Light Flashes or Stays On If the clip light flashes, the signal level to the equalizer is too high. Turn down the level on the unit feeding the PQX equalizer. If the clip LED is on all the time, disconnect the input and output cables. If it is still on, the unit must be returned for service. 8.4 Distorted Sound This will only be caused by too much signal which will show on the clip light. If the light is not flashing, there is an overload somewhere else in the signal chain. Adjust the gain of each component in your signal chain until the unit which is distorting is found. 8.5 Excessive Hum or Noise Hum will usually be caused by a “ground loop” between components. Try using the suggested balanced input and output connections if the other pieces of equipment used in conjunction with your equalizer have balanced inputs and outputs. Noise (too much hiss) can be caused by insufficient drive signal. Make sure you are sending a nominal 0 dBu line level signal to the equalizer. The input ground to chassis ground jumper strap supplied with the equalizer should normally be left in place to minimize ground loop voltage and for safety reasons. If hum or buzz noise is still heard after you have in...
Эта инструкция также подходит к моделям:Ресиверы и усилители - PQX-571 (107.64 kb)