Q in LPF

[Joe Wright]

In rbj's LPF, how should I interpret Q?  I'm a bit vague as to the meaning
of Q anyway and I can't seem to alter the resonance of the filter to any
great extent.  What range should Q take on.

Formular posted below.

Thanks


Joe Wright - Nyr Sound Ltd
http://www.nyrsound.com
info at nyrsound.com
Tel: +44 (0)1202 383145
8 Cringle Avenue
Bournemouth
BH6 4HX
UK

    omega = 2*PI*frequency/sample_rate

    sn    = sin(omega)
    cs    = cos(omega)

    alpha = sn/(2*Q)


LPF:            H(s) = 1 / (s^2 + s/Q + 1)

                b0 =  (1 - cs)/2
                b1 =   1 - cs
                b2 =  (1 - cs)/2
                a0 =   1 + alpha
                a1 =  -2*cs
                a2 =   1 - alpha


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