[sdiy] Simple clickless FET mute switch?

[harrybissell at wowway.com]

Of course, but not said... is that the mute signal cannot
disturb the DC operating point or you will get huge clicks.
This happens a lot in stompboxes (single supply) if they lack
proper pull-down resistors on both sides of blocking capacitors.

H^) harry



On Wed, 17 Sep 2008 16:38:53 +0200, Mattias Rickardsson wrote
> 2008/9/17 John Mahoney <jmahoney at gate.net>:
> > At 08:38 AM 9/17/2008, Mattias Rickardsson wrote:
> >> [snip]
> >> > To avoid the click it needs to be either zero-crossing.
> >> > Or be a gradual fade over at least 10ms.
> >>
> >> Well, switching a signal instantaneously at a zero crossing also gives
> >> a click, albeit a mufflier one. Otherwise, triangle waves would be
> >> silent, you know! :-)
> >
> > Um, no, I don't know! You've completely lost me, there.
> 
> When a signal is turned off to zero at a non-zero timing, you will
> hear a strong click at the "discontinuity". Now, if you instead turn
> it off where the signal would cross zero, the result will not have 
> any sharp "discontinuity" anymore, but a sharp "corner" - which is also
> heard, but it doesn't contain such a lot of high frequencies... so it
> might be OK in some applications. But probably not with a bass tone.
> 
> Take a square wave as example. Integrate it, and you get a triangle
> wave. The "discontinuities", which are just like the switched non-
> zero signal above, are removed and you have "corners" instead, like the
> zero-aligned switched signal above.
> 
> The integrator is in fact a one-pole lowpass filter. -6dB/oct.
> So "corners" are like "discontinuities" run through a one-pole lowpas
> filter. They are still heard.
> 
> How did that sound? :-)
> 
> /mr
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Harry Bissell & Nora Abdullah 4eva