Read it here

http://www.producerspot.c...thing-you-need-to-know

A good intro to the subject, although it should have been titled "The Bare Minimum You Need to Know About Reverb".
 
Fact check: the Beatles would be surprised to know that the plate reverbs they used at Abbey Road had not actually been invented yet. At least, according to the article, which dates them to "the late 70's". 
 

The first EMT 140 plate reverb was released in 1957. It only had a mono return but in 1961 they fitted it with a stereo return. eg two pickups. In 1976 they produced the all digital electronic EMT 250 so that is what they may have been talking about.