Originally Posted by NoHyperbole

I had a Kenwood DDX 512 in my 350Z. In response to OP's question, and for everyone's general knowledge, if I am not mistaken, the Q factor determines how "wide" of an effect each EQ step up or down on a given frequency will have on the frequencies immediately higher and lower than the particular EQ frequency. A numerically smaller Q factor will limit the effect of an EQ change to a smaller frequency range, while a numerically larger Q factor will apply a given EQ change to a wider frequency range.

Let's say you boost a particular frequency by 5 and that the Q factor is larger, like 1.5. Imagine that the EQ curve will look like a triangle, with the peak of the triangle as the frequency you boosted by 5. The base of the triangle will be wide because your Q factor is larger. The width of the base of the triangle represents the frequency range; the wider the base of the triangle, the wider range of affected frequencies.

Now let's say you boost that same frequency by +5 again, but this time the Q factor is smaller, like .5. The peak of this triangle will be the same, but the base will be much narrower because your Q factor is smaller.

In both cases, the surrounding frequencies (both higher and lower) are changed, but the frequencies that are changed in the second example are closer to the original frequency that was boosted.

I realize this is really abstract, and I hope this all makes sense and that I am correct. If anyone wants to chime in, I welcome that.