Crystal filters for 50 kHz channel separation FM radios have a bandwidth of 30 kHz. These filters are usually built from conventional crystals contrary to more modern filters which are built from more complex quartz resonators.
More modern filters are smaller and they are usually designed for smaller channel separation.
Filters like the ones in fig. 1 contain 8 useful crystals each. Old-fashioned 10.7 MHz filters for 50 kHZ channel separation. These filters contain very useful crystals like those shown in the figure. To obtain a bandwidth of 30 kHZ a typical filter is designed like in fig 2.