1. Typical Uses
The PEQ-5B allows creative audio processing previously not possible with graphic or less advanced parametric equalizers by enabling the user to set all filter parameters center frequen- cy, bandwidth and amplitude) in five separate bands. These bands cover the entire 20 Hz to 20 KHz audio range and the frequency ranges of the individual bands overlap, allowing two bands to be set to one center frequency for added boost/cut capability. The PEQ-5B can be used both by itself or in conjunction with conventional graphic 31 or 15 band equalizers. In live sound situations, for example, the graphic EQ can be used for the rough mix and the PEQ-5B can be used to help fine tune the overall sound.
One of the PEQ-5B's most useful capabilities is notching out troublesome frequencies caused by feedback in live mixing, for example, or hum or appliance noises in recording appli- cations. When such problems require extra cut than can be achieved by a single filter, simply adjust two filters to the same center frequency and bandwidth. Setting both LEVEL controls then to the left stop position doubles the amount of notching. Similarly you can also achieve doubled boosting (peaking) when needed, by adjusting both LEVEL controls to the right stop position.
(Notes:
a. Since all narrow-band filters produce a slight phase shift and thus time delay of the signal, care must be taken with extremely narrow and high gain settings to avoid annoying "ringing" sounds. Always set all filters not in use to mid-travel position or switch them off to minimize such effects.
b. To avoid damaging connected equipment and cause unde- sirable effects such as distortion or feedback, always start with all controls set to mid-travel position and all IN/OUT switches OUT.)
Troublesome frequencies that are to be notched out can be identified by ear (although that requires some trial and error and a bit of patience, or more effectively by the use of an audio spectrum analyzer. Resonance frequencies can then be quickly identified, enabling quick tuning of the required filters on the PEQ-5B.
(Note: If feedback notching is the only task you have planned for the PEQ-5B, you should consider also the Nady FS-4N Feedback Suppressor, which features 4 notching bands and a built-in audio spectrum analyzer for the quickest, most effec- tive feedback suppression possible.)
If a spectrum analyzer is not available to help identify trouble- some frequencies, it is most effective to do so by actually rais- ing the gain in the narrow-band filter at first to make them heard, and then simply eliminating the undesirable frequen- cies by subsequently lowering the level.
The PEQ-5B can also be used for a wide variety of other applications other than narrow-band notching. For example: to simulate speaker crossover networks, or simple tone cir- cuits, or even for drastic modifications such as "telephone voice". Since broad band frequency corrections are the most common type of equalization in live sound applications, the PEQ-5B can be easily utilized for this purpose by 2 or 3 broad-band parametric filters in combination with the low and high-cut filters to achieve the required overall frequency equalization. Then the remaining 2 or 3 bands can be used to eliminate feedback and correct room resonances. The PEQ-5B can also be useful to help compensate for problems of poor microphone positioning and/or increased intelligibility.
Room acoustics can also be corrected for poor speaker place- ment dictated by other than pure acoustic considerations.
Once all the equalization has been adjusted as required by the application, the INPUT control is used to set the overall level of the PEQ-5B's processed signal. The signal can be raised or lowered as desired. Use the IN/OUT switch for a direct A/B
comparison as a guide for proper level adjustment.
