Quick input/output switching question

[LakeFX]

I'm working on a preamp bassed on the HPF v2 from tagboard to use when doubling on bass (both bass guitar and electric upright). I am going to add a switch that both switches between inputs and between volume pots at the output of the board.

My questions are how important is it to ground the unused input? Or, can I just use one pole of the switch for the board input and the throws for the tip of each input?

Also, on the output side, do I need to disconnect both the output from the board and the wiper from the volume pot that is not in use? Or what are the ramifications for just switching between which wiper goes to the tip of the output jack and then double the values of the volume pots?

If there are no problems with the simpler of these switching methods, I can get away with a single 3PDT switch. Otherwise I need to use a relay switching board to get 4PDT plus LEDs.

Here's what I'm picturing:



Thanks!

[mth5044]

A schematic of the 'big picture' would be helpful.

[LakeFX]

The vero layout I'm going to use is at:
http://tagboardeffects.blogspot.com/2015/01/hpf-technology-hpf-pre-2.html?m=1

And the details of the original circuit are from:
https://docs.google.com/viewer?a=v&pid=sites&srcid=ZGVmYXVsdGRvbWFpbnxocGZ0ZWNobGxjfGd4OjQyNGJhOWE3YzdjMDY0ODg

All I plan to modify is to add switchable inputs and make the volume pot switchable between 2 different pots to match volumes between the inputs.

[MrStab]

from what little i understand of the setup, i think you could probably get away with not grounding the other input, but it might depend on what you have going into it. usually it's the board itself you wanna stop from oscillating, but that's not to say something earlier in the chain couldn't introduce noise problems.

as far as i can picture it, because you're not putting the amp side of things into an open circuit, it's probably okay to leave the inputs ungrounded. it'd be a different story if we were talking about leaving a hot signal connected to the amp hanging.

if you find that you do need to ground the inputs and don't wanna fork out for a 4PDT, maybe you could try hooking up some NPNs to RG's Millennium Bypass circuit to shunt the signal(s) to ground.

[LakeFX]

Thanks! I'll breadboard it to see if there are issues. I just wanted to make sure that there wasn't something I didn't know about that would save some time.