Microphone off switch

[robbiemcm]

If I use a double adapter in to my amp, and plug in both my guitar and a microphone, when I turn the microphone off my guitar won't work. Am I right in assuming that this is because when the microphone is switched off, it grounds the signal, so my guitar signal is just getting grounded through the microphone?

If all that is true:
Why don't they just break the connection instead of grounding the signal?
Is there any way around this problem, excluding just using two amps?

[Nasse]

Maybe you could build some kind of mic preamp or buffer with suitable input impedance for mic, and some kind of noiseless electronic switch in that.

Another solution might be a simple mixer in front of the amp input

I recall some talk about such mic switches in some musicians forum. I think some pro said his opinion he prefers to buy mics without any switches, because some always accidentally uses the switch when mic channel is full up and the tweeters and woofers get nasty torture

But for us hobbyists or for home studio or something the coolest control ideas and some info can be found here: http://www.geofex.com/Article_Folders/automike/automike.htm

[R.G.]

If I use a double adapter in to my amp, and plug in both my guitar and a microphone, when I turn the microphone off my guitar won't work. Am I right in assuming that this is because when the microphone is switched off, it grounds the signal, so my guitar signal is just getting grounded through the microphone?

Yes, you are.

If all that is true:
Why don't they just break the connection instead of grounding the signal?

Because an open mic cord picks up massive hum, buzz and RF. Shunting it is the only way to make it quiet.

Is there any way around this problem, excluding just using two amps?

As Nasse points out, anything that doesn't let the mic and guitar signals share a physical wire going into the amp works. Any buffer or mixer with a separate electrical input for the mic would let it be turned off by the mic switch without muting the guitar. A single-opamp buffer is one simple solution and could be put into a tiny-box "dongle" at the amp input. A simple mixer would let the mic mute its input without muting the guitar, or an A/B/Y box would do it.

[Paul Perry (Frostwave)]

If you really are using a double adaptor, then you might want to try to rewire things so you are putting the signals in SERIES instead of parallel.
That way, when the mic is off, you are bypassing it & just the guitar signal goes in.
WARNING: I havn't tried this!