melos cdt-ii question: what is deem.?

[non-prophet]

For conversation purposes, i recently found a melos tube cd player.  I have owned 3 of the 2 chassis melos tube cd players. Two of the units had a third rca input/output marked "deem."  With the period, as if it was an abbreviation.  This is on both the cd player and tube stage, i have no idea what it is or does, any help would be appreciated.  I can't even tell you if it changes the sound since both cd players that had it did not work, the tube stage works without using it.  What is DEEM.?  Thank you, nick

[Dicky]

De-emphasis

[OldiesButGoodies]

De-emphasis

Agree.  Very few audio CDs were ever recorded with pre-emphasis,  a noise-reduction technique that requires a de-emphasis filter on the playback end,  so you are not missing much by leaving it disconnected. If the CD has the right flag on in the subcode the player is supposed to turn on the de-emphasis eq curve to bring the mids and treble back down.   

[non-prophet]

Very interesting, must be a pro audio thing, i never heard of it.  Thank you