Resistors between stages.

[Sam]

You often see resitors between the stages of circuits, which to my knowledge, is put there to controll the gain between these stages. Sometimes they are wired in series with the signal and other times from signal to ground. Can someone please enlighten me why and where one is prefered over the other?

[Transmogrifox]

This is a hard one to satisfy with a blanket answer.  Sometimes the resistor to ground out of an op amp stage (for example) is placed there to bias the output into a class A mode to reduce crossover distortion.  Sometimes a series resistor is added to set a ball-park high frequency roll-off with the input capacitance of an active device to filter RF noise.

Other times, there may be a resistor divider network in  place to reduce gain between distortion stages to make it distort differently.

When using OTA's, they have a very low differential input voltage range, so you need to divide the signal level down low enough so it doesn't distort a filter.

In many cases, these resistors are placed as part of a biasing scheme to keep active devices in a linear operating range.

Sometimes it's part of an RC network for the purpose of frequency emphasis/de-emphasis.

Sometimes it's a part of a phase/frequency compensation network with stray capacitance/inductance in other circuit components and is there to prevent high frequency oscillations (which result in increased noise and distortion for ultrasonic instabilities, and an irritating whine, squeal, buzz or hum for audio frequencies).

Sometimes it's just a habit formed by a designer to put a resistor in certain places just because it seems like it should be there...call it art if you will.

Any circuits on your mind to use as a specific example?

[Coriolis]

Hey that was a good answer!
It's almost a checklist for schematic analysis...
Bookmarked!
C