Lets start at the souce, A phono cartridge is the the thing at the end of the tonearm that contains the needle. This is probbably the most critical device in the LP playback chain because it is what is actually reading the grooves in the record and translating them into electrical signals which are then turned into sound later on down the chain.
Once the electrical signal is generated by the phono cartridge it goes into a phono preamp which equalizes the signal using the RIAA curve, The RIAA curve is a standard equalization to normalize the signal generated. The signal is equalized before it is cut into the record, therefore it must be "un-equalized" when its read back off the record. The phono preamplifier then amplifies the signal to a higher level suitable to feeding into a standard preamplifier whos only job is to switch inputs and adjust the signal level to match the users input on the volume control knob.
