Being able to change the key of tracks even just 3 musical half steps is a big plus when mixing, mashing, and doing a controllerism routine. Why? Let’s say you are playing a song in the key of C, so mixing harmonically, your next song should be in C, G, F, or Am.
Out of (imaginary number) 100 songs that are close enough in BPM to the track playing to mix in well, only 15 of them are in keys matching the ones that will mix harmonically. Using the key knob to change the other 85 songs keys, you would increase the number of possible songs to mix in to 30 or more. This number mainly depends upon how many songs (out of the 100) are in a major or minor key, because 3 musical half steps from C, G, F, or AM is pretty much the whole chromatic scale.(all the notes on a keyboard black and white)
If this all sounds greek to you, start by learning the Camelot system of harmonic mixing which was designed for DJ’s.
Basic music theory is also very good to know. Major and Minor scales, chromatic scale, and basic chord progressions(which is the Camelot system actually). You may not be playing an instrument, but you are playing music, right?
On getting the Key to change an exact amount, I ended up mapping some keys to do it exactly. If I remember right moving the mouse left to right changes amounts slower than up and down.
The tuning method is ok, but if you learn the distance between notes, and already have your song’s key information, you can do it instantly. Example: Song is in D I need it to be in C (2 musical 1/2 steps lower)so I move the key knob to -2. Done.
Harmonic mixing is not really next level as far as I can tell. I’m fairly new to DJ’n, but an old musician. Seems like DJ’s have been harmonically mixing for many years now, from what I have read. Many were probably doing it with out knowing, just playing what sounded good. Now many DJ’s use Mixed in Key software to get the key info and embed it into the track’s info, and have learned what keys mix well( Camelot system), and have learned the distances between musical notes. So when mixing it would literally only take a second or 2 to manually change the key of a song to harmonically mix with another.
Hope I’m not just adding mud to the murky water here, lol.