Here a real bit of audio nostalgia for ya'. Dynamic Coupling Factor (DCF) was a trademarked slogan of PIckering in the late 60's, and a proprietary expression of Stanton Magnetics throughout the next several decades. Just what did it mean?

It was actually a very real formula, developed by Pickering engineers to apply a numerical value to the quality of each component within one's audio system, and then use that number (the system's Dynamic Coupling Factor) to select a corresponding cartridge. The term was initiated in the late 60's with the Pickering XV/15 line of cartridges, each of which had its own "DCF" ratiing, ranging from 150 to 750, and then later, to 1200.

There was never a more difficult to explain, more patently ridiculous and idiotic concept as Dynamic Coupling Factor, or "DCF" when discussing cartridges, and, not surprisingly, XV/15 models with DCF's of 400 or 750 worked equally well in many a given system, so the entire idea was pretty much useless.

Add to that the fact that the XV/15-625E, introduced in 1976 (simulaneously with the XSV-3000) and sandwiched between the XV/15-400E and XV/15-750E was a better cartridge than the 750 in every respect. The sales dud, the XV/15-1200E found all new life, and industry acceptance when it was introduced to the world in a different package, with different structural cosmetics (though no functional differences) and under a different name. What was that? The Stanton 681-EEE!!!

There. Now you can all sleep better.