Can I trim a NFL?

[LektroiD]

I'm using an op amp to drive a mic input, seems in practice the level is too high. I put a trimmer in, and yes it works, but there's a lot of pops and crackles. Would that be down to the trimmer quality, or is there a better way to do this?

[rs20]

Does turning the pot really adjust the volume? Have you drawn the entire circuit, or left out a resistor from the - input to ground? Because what you've drawn there is a op-amp buffer circuit with a gain of 1, regardless of the feedback resistance (assuming an ideal op amp).

Is it popping and crackling while it's just sitting there, or only when you adjust the volume?

[dom0]

There's something missing in your schematic.

When using pots as a rheostat [adjustable resistor] it's often advisable to put some fixed R from the wiper to the end to avoid/lessen the problem you are describing.

While adjusting the gain of amplifiers at audio frequencies is usually not very troublesome keep in mind that it changes many properties of the amplifier. Compensation for stability must be done at the lowest settable gain ; phase margin should be plenty as pots are not precision devices and will drift with wear.

[LektroiD]

How's this look? I also included the rest of the circuit...