Switched and unswitched jacks

[TheOneOnTheLeft]

I'm building a muff pi clone (using this schematic http://www.tonepad.com/getFile.asp?id=94) and while looking at components I came across two different types of jack input; switched and unswitched. I couldn't find any explanation of the difference on google or the FAQ, so I was hoping someone could explain it to me, and recommend which to use if there's a reason to use one over the other. Thanks!

[digi2t]

You don't need a switched jack for the input side. Use a stereo jack. This will allow you to wire it such that you disconnect the battery when you remove the instrument plug from the input side.

Switched jacks are generally used for other purposes, i.e. going to ground, or bypassing, when no plug present.

Looking at the schematic, it might be that you're confusing the switch symbol directly after the jack, as part of the jack itself. In reality, this represents part of the footswitch.

Cheers,
Dino

[TheOneOnTheLeft]

Ah right, much appreciated, thanks.

[Mark Hammer]

Switched jacks are handy for those circumstances where you want some alternate action to take place when the jack is not being used.  For example, headphone jacks often route the signal to the speaker/s when nothing is plugged into the headphone jack.  In the tradition of modular analog synthesizers, such jacks were used for "normalized" connections.  For example, the output of an oscillator would go to a filter and then to a VCA...UNLESS you plugged something into the jacks that sat between these segments.

Many delay-based pedals use switched jacks for their output, combining wet and dry at one output if only the "mono" output jack is used, but sending the wet and dry signals to separate outputs if both jacks are used.

[CodeMonk]

Switched jacks are handy for those circumstances where you want some alternate action to take place when the jack is not being used.  For example, headphone jacks often route the signal to the speaker/s when nothing is plugged into the headphone jack.  In the tradition of modular analog synthesizers, such jacks were used for "normalized" connections.  For example, the output of an oscillator would go to a filter and then to a VCA...UNLESS you plugged something into the jacks that sat between these segments.

Many delay-based pedals use switched jacks for their output, combining wet and dry at one output if only the "mono" output jack is used, but sending the wet and dry signals to separate outputs if both jacks are used.

I used switching jacks when I added an effects loop to my Vox AD30VT.
Both jacks had to be plugged in, otherwise it would bypass.

[Mark Hammer]

Right.  I was so caught up in explaining normalized patching, I completely forgot about the obvious: send/receive loops.