However, there is something you can do to keep it at a minimum.
It's a principle called "gain staging."
As the musical signal goes from your microphone through your mixing board to,

a master tape, the musical signal passes through several electronic stages.

A typical case:

Microphone preamp to Channel fader to the Output fader to the tape recorder input.

At each stage, electronic noise will be added to the signal.

The trick to keeping this noise as low as possible is to have the signal enter each stage 

as loud as possible, without  causing unwanted distortion. At the same time, we want to avoid, 

as much as possible, having to boost the signal as we go.

First,  make sure the signal from your microphone is loud and strong. 

This is the first stage in the chain. If a signal is weak, try a more sensitive microphone, 

move it closer to the source, or make the source louder.

Next, set both the channel fader and output fader at 0, or as it's sometimes called, "unity gain". 

If the signal to your multitrack tape recorder is too "hot", first try turning down the input level control 

on the tape recorder.

During mixdown, make sure the signal from your multitrack to your mixer is as loud as possible without  overloading the mixer. Then, if the signal to your master deck is too hot, begin 

cutting it at the master deck itself, and work your way backwards through the chain of stages.

If you add outboard processors to the chain. Send the processor as hot a signal as you can, and if 

necessary cut it at the output of the processor.

It's not always possible to follow these rules, but if you look at your mixer and see the channel 

fader at minus 10 and the output fader at plus 10, you're begging for a noisy recording. 

Try putting that channel fader at zero and cut the output fader instead.