Originally Posted by SuBiElOvEr
Can someone explain what the Q is?
For an equalizer, it defines how sharp the rolloff is from the center frequency. The higher Q (red) has a narrow band, while the lower Q (blue) has a greater bandwith with gentler rolloff. There will be more overlap from an adjacent band with a lower Q. It tells how "wide" the affected area is when you raise/lower EQ band level cut for a particular center frequency. If an EQ with a low Q (e.g. the blue graph) is raised then surrounding frequencies (because of a wider bandwidth) are raised as well. As the Q goes up the bandwidth narrows. Think of a 3-band EQ having low Q and an 11-band EQ having a much higher Q.
For a radio, the tuner would require a very high Q to isolate adjacent channels.
The Q of a speaker shows how resonant the driver (or driver-enclosure combination) is. The rule of thumb is that big magnets and big enclosures give a low Q. The lower the Q, the more tightly does the magnet control the movement of the cone, whereas a very high Q driver would not and occillate at resonance. When a speaker is installed in an enclosure, the resonant frequency changes and so does the Q.