Switching question

[alparent]

OK this question is going to reveal how little I actually know!   But here it goes....

Lets say I want to add a switch to select between 2 resistors. Is it better to use a DPDT switch to isolate both sides of the unselected resistor or is using a SPDT switch on only one side of the resistor and leaving the other side connected as good?


Same kind of question about tru-bypass. In tru-bypass only the line-in and line-out connections are ether connected to the effect or connected together for tru-bypass. The grounds of the jacks are always connected to the effect. I'm using a 4P3T rotary switch to switch my effects (Effect ON - Bypass - Mute) so I'm using the 4th pole to cut out the ground from the effect when the effect is not on.
I'm I doing this for nothing? I'm I over doing it?

Is this clear or to confusing?

Thanks for the info!

[alparent]

bump

[jdub]

Hi Alain-

"Best" switching method to some extent depends on what you are switching.  Can you be more specific? In general, and if you have the space, I would probably go with the DPDT method, but you might be able to use a SPDT depending on application.

As for the bypass switching, I would first recommend R.G.'s article here: http://www.geofex.com/Article_Folders/bypass/bypass.htm.  It's got some great info; I would add, however, that 3PDT switches for bypass are easy to get now (for example, see Aron's store).  I usually use a true bypass scheme that grounds the board input when bypassed (using a 3PDT), as in method 5 here: http://www.tonepad.com/getFile.asp?id=76.  I must admit I'm unclear as to what "mute" does in your rotary switch method- does it block the guitar signal altogether?

Again, if you could add a few details (type of effect, what you're switching, desired outcome, etc.) that would help. Cheers!

[G. Hoffman]

The SPDT should work fine, because the other end of the resistor is floating in mid air.  The reason true bypass works better than not is that the effect is still putting a load on the signal, because it is still connected to stuff (+9V, ground, stuff like that).  

Now, there may be other issues I'm not thinking of, but in general, if a component is not connected to anything on one end, it shouldn't have any effect.


Gabriel