Graphic EQ Week 2 PowerPoint
GRAPHIC EQ: Common type of EQ, has banks of SLIDERS to control specific FREQUENCIES • Sliders can ADD or SUBTRACT dB • Subtractive is usually better • BANDS: Each specific frequency control • CAR: May have as little as 2 bands (BASS and TREBLE) • LIVE SOUND: 25 to 31 bands What is Graphic EQ?
THIRD-OCTAVE EQ: Most amount of bands. Each is a third-octave from the next • 2/3 octave EQ: Second most bands. • Less precise, but more general control • Often used to eliminate FEEDBACK Definitions
Historically, the first use of slide controls in an equalizer was in the Langevin Model EQ-251A which featured two passive equalization sections, a bass shelving filter and a pass band filter. • Each filter had switchable frequencies and used a 15 position slide switch to adjust cut or boost. The first true graphic equalizer was the type 7080 developed by Art Davis's Cinema Engineering. It featured 6 bands with a boost or cut range of 8 dB. It used a slide switch to adjust each band in 1 dB steps. • Davis's second graphic equalizer was the Altec Lansing Model 9062A EQ. In 1967 Davis developed the first 1/3 octave variable notch filter set, the Altec-Lansing "Acousta-Voice" system. Some History
In software: NOTCH filtering is a narrow band to pinpoint frequencies • SUBTRACTIVE EQ: Why is that better? • Simple HI and LO pass: when are they used? • What is OVER and UNDERSHOOT? • Adjusting Q: What is it? • What is LINEAR-PHASE EQ: Phase shift introduced that is proportional to the frequency Concepts of EQ