nF is used a fair bit in audio circuits. Nanofarad-range capacitors, typically from 1 to 100 nF, often appear in filtering circuits. From time to time, values d

nF is used a fair bit in audio circuits. Nanofarad-range capacitors, typically from 1 to 100 nF, often appear in filtering circuits. From time to time, values down to around 300 to 500 pF may appear. Anything around 100 pF or less is typically for dealing with unwanted high frequencies in some way. On the other end of the scale, microfarad-range caps in the signal path appear as couplers into low-ish impedances, where good bass response is required. For doing things" with the signal, other than passing it through with bass intact and filtering out RF, the workhorses tend to be caps that are nicely measured in nanos. In terms of brevity on a schematic, it about breaks even for two-digit nF values and wider as in 22n vs .022, and only when we have a blanket rule that when units multipliers are omitted from capacitors, they are understood to be μ. 2n is shorter than .002; and harder .0047 is easier to misread as .047 compared to 4.7n. NOTE: You will may across audio schematics which do not write the "n"! It is assumed that any capacitance which is an integer like 33, or a real number >= 1 like 2.7, is nanofarads! Together with the convention that fractional capacitances are implicitly microfarads, so that 0.47 is microfarads. In my local brick-and-mortar electronics shop, packages of capacitors 1nF and higher tend to be labeled in nF if they are film caps or ceramics. Electrolytics use μF; a bag of 0.1μF electrolytics would be labelled that, and not 100 nF, but the same-valued film cap will probably be 100 nF.