Keavin, Q stands for quality. It's an archaic term which basically describes how a tuned circuit operates. Think of the shape of a volcano. Let's say that the peak of the volcano is a resonant circuit peaking at 1 kHz (1000 Hz or 1000 cycles per second). To the left, the peak drops off at frequencies lower than 1000 Hz. To the right, it drops off above 1000 Hz.
Q is a number which represents how steep the sides of the volcano are. Higher Q means steeper sides.
You actually hear this when you turn up the CVQ, or Constantly Variable Q, knob on a Series 2. As you increase the Q, you hear a sonic difference in the response of the filter. It's steeper, therefore sounds more vocal and the sharp peak stands out more.
Lower Q settings give you a less steep peak and it is more of a gentle roll-off above and below the resonance. On the Alembic filter, it's a lowpass, so the rolling off is done on the high side.
If you imagine a graphic equalizer it may help. If you push the middle slider all the way up, and the others all the way down, that's high Q. If you make a gentle slope peaking at the center frequency, that's low Q.
The Q switches on the Series I and other instruments means that instead of a variable Q with infinite steps (a pot) you have a switch that selects one or two levels.
Does that make sense now?
It all dates back to when inductors (coils of wire) were first wound in the vacuum tube days. People needed a term to tell what the coil was specified to be, with steep or gentle roll-off at the resonant frequency of the circuit it was used in. Nowadays, Alembic filters use integrated circuits instead of coils to make these peaks, but the term sticks.
EffClef
PS - does anyone here have the capability to put their Series bass on a spectrum analyzer? I would love to see this stuff in action, visually. That would be a great thing to post. (I am sure Ron's lab is full of them, but maybe someone here has one. I wonder if one of those computer sound card spectrum analyzer programs would work well enough.)
