Any electronic or acoustical device used, to simulate the natural reverberation of a large concert hall, or to produce a reverberant effect.
"I received th CDs last week. They are fantastic. My wife had 'butchered these recordings as LPs and I had little hope for any more than a scratchy recording. What I got was a recording that was 99.99% clean - approaching the quality of the LP whan it was new. Thanks"