[pree-am-pluh-fahy-er] 
| a device in the amplifier circuit of a radio or phonograph that increases the strength of a weak signal for detection and further amplification. |
| pre·am·pli·fi·er (prē-ām'plə-fī'ər) n. An electronic circuit or device that detects and strengthens weak signals, as from a radio receiver, for subsequent, more powerful amplification stages. |
pləˌfaɪ