input jack going into op-amp - floating when disconnected?

[eyAyXGhF]

Hey all,
Sorry if the subject is misleading, it's a pretty simple question.

I have a small amplifier circuit using a pair of op-amps. Occasionally the input source (impedance 10K-100K) to this amplifier can be disconnected, what is the best practice for this? If the input source is disconnected, the first op-amp stage is left floating.. which isn't good I'm guessing.

Do I just use a large value resistor (1M or more?) and tie the op-amp input to ground so even when the source input is disconnected it isn't left floating?

 

[Nigel Goodwin]

There should be a resistor on the opamp input at all times, it's very bad design if you didn't fit one.

But posting your circuit would help.

 

[MikeMl]

There should be an internal DC path to supply the input bias current to the opamp regardless if the input source is connected or not. Think about how you would do it if the input source had to be AC coupled through an input DC blocking capacitor...