Q is kind of a measurement of resonance, then. Another engineer's measurement of Q is to divide the center frequency of the filter's response by the difference between the frequencies where the response is 1/2 of the center response. Your finger has lowered the Q of the vibrating string, removing a lot of energy from it each vibration, so it stops vibrating quickly. If you put your finger on the string, it stops ringing very quickly because your finger damps it, removing a lot of energy as the string moves. It dissipates very little of its energy per cycle, so it stays in motion a long time - it's a high Q mechanical filter. The initial pluck that sets it into motion stores a chunk of energy in the string that is saved by the interchange of motion for string stretch on every vibration. Let me translate that into something more useful.Ī guitar string will vibrate a long time if plucked. The techie explanation is that Q is the energy stored divided by the energy dissipated per cycle in a network. 'Wait a minute! What's Q?' I hear you ask. The diagram shows the possible frequency responses of a variable Q peak/notch filter. Sometimes a notch can be very useful in getting a specific sound.Įven better would be if you could get either a peak or a notch, depending on how you set the controls - something like the frequency response diagram.

Not so familiar is a notch, or a sudden reduction in level at one frequency. This is a resonant peak in the signal that can get moved around. Sooner or later you might wonder if there is a more general solution to messing with tone controls.Įveryone is familiar with the sound of a wah pedal. While this is fun, it's not very flexible. If you're into playing with tone controls and notch filters to see how they change the sound out of your effects, you will undoubtedly have built several glops of R's, C's and pots, maybe some L's to make up the tone networks. Simple, Easy Parametric and Graphic EQ's, Plus Peaks and Notches

3 band parametric eq