AB box with spdt switch

[Nordskov]

Hi there.

I want to build a simple AB switch for my bass rig.
I have two basses and one amp and want to switch basses without fiddling with the cables.
So the box will have 2 inputs and 1 output. The box will be placed on the amp and operated by a spdt rocker switch (so not really a stompbox:)
All AB box schematics I can find have 1 input and 2 output and are operated by a dpdt switch. This makes sense as a spdt switch will leave the unused output open and induce hum.
But I pretty sure an open circuit on the input side (unused input) will do no harm.
Am I right?

Should I worry about noise when switching between inputs?
If so, what can be done?

Cheers,

[PRR]

> Am I right?

Yes.

[Nordskov]

> Am I right?

Yes.

Thx PRR for a quick reply

And no noise issue when switching? Click, pop, thud etc.

[GibsonGM]

A click or pop is generally the symptom that there is DC on one of the switch contacts (that they are at different potentials).  If it's not powered, and you're using a bass, there should be no level difference.    If you have effects in line, it COULD result in some DC there due to a leaky output cap or some such thing.  Could also emanate from your amp in the same way.   What you propose would not make me nervous.     

Go ahead and try it if all you have is a SPDT - you can cause no harm.  A DPDT switch is usually used so you can ground the unused input and silence it 'definitely'. Really, you are probably totally fine with your plan if it is inside a metal box and you tie that box to ground. 

[Nordskov]

A click or pop is generally the symptom that there is DC on one of the switch contacts (that they are at different potentials).  If it's not powered, and you're using a bass, there should be no level difference.    If you have effects in line, it COULD result in some DC there due to a leaky output cap or some such thing.  Could also emanate from your amp in the same way.   What you propose would not make me nervous.     

Go ahead and try it if all you have is a SPDT - you can cause no harm.  A DPDT switch is usually used so you can ground the unused input and silence it 'definitely'. Really, you are probably totally fine with your plan if it is inside a metal box and you tie that box to ground.

It will be housed in a metal casing. I have no effects between my basses and the amp, although one of my basses is active.
I'll give it a try and see what happens. Otherwise I can get a dpdt switch.

Thank you both for responding

[GibsonGM]

Well, the DPDT (or 3PDT!  To add an indicator LED) is standard now, but the single pole will work.  If you have any DC leaking from the active bass, yes, that would pop.  Try it out!  You will know very quickly if it works   

[Nordskov]

Well, the DPDT (or 3PDT!  To add an indicator LED) is standard now, but the single pole will work.  If you have any DC leaking from the active bass, yes, that would pop.  Try it out!  You will know very quickly if it works   

I have three reasons for the rocker switch:
1. Less cables on the floor The other bass is in a stand by the amp along with it's cable. The box will be placed on or near the amp)
2. No need for indicator light. The rocker points at the active input.
3. It's the only one I have

It can be upgraded for a stomp switch later if nessesairy. Its easier to drill the hole bigger than smaller.

[GibsonGM]

There's nothing wrong with that, Nordskov   

[Nordskov]

There's nothing wrong with that, Nordskov 

Thank you sir.
Necessity is the mother of... etc - on a very basic level

Holes in the box are drilled. Just realised I miss a nut for one of the jack connectors - dammit.

[GibsonGM]

I gave you your first "Like" because you are taking the initiative and trying this out   

[Nordskov]

I gave you your first "Like" because you are taking the initiative and trying this out   

I didn't notice your like before you brought it to my attention