From the Jan edition of SOS when reviewing Kontakt5:

"The resonance of the filters can be pushed into self-oscillation. By tuning the cutoff frequency to track the keyboard over an evenly tempered scale, you can easily achieve the classic 'singing filter' effect of analogue synths."

It is the bit in bold I dont understand

It actually means you can play the filter like an oscillator as it self-oscillates.
The bold text means you set the keytracking parameter such way,
that one octave is divided into 12 equal intervalls (evenly tempered scale),
so the filter's pitch follows the keys on your keyboard in half steps.
Or in another words, you set the keytracking such way so that the filter is producing a pitch exactly one octave higher, if you play two keys consecutively one octave apart on the keyboard.

Cheers

Yeah, they've just thrown 'evenly tempered scale' in there to sound clever. Unless Kontakt (or any other synth) is somehow geared toward experimental microtunings, even tempered (or rather equal temperament) is always the default mode of operation with regard to the pitches you get when you play different notes. They just mean that you can push your filter into self-oscillation, link cutoff to keytracking, and play the resultant filter whistle as though it was an oscillator on your keyboard.

Equal temperament is just the tuning system we use for all instruments today so that you can play in any key and things will sound good. In ye olden days, there were a few competing tuning systems which sounded slightly purer when you played in certain keys, but sounded dissonant in others. They called the intervals which didn't work in those tunings 'wolf-notes'. Equal-temperament is just a compromise tuning system so all intervals sound good in all keys, even if a some intervals are actually a few cents away from mathematically perfect.

omg extraneous vernacular in the music tech industry to belittle nescient end users? never!!!

ftr, for any casual readers who wish to know exactly how ET works,

octaves are a logarithmic scale, twice the frequency, right... so octaves are powers of two, 2^1=2, 2^2=4, 2^3=8 et c..

..and if you're not familiar with using powers computationally, negative powers are roots.. eg. 2^0=1, 2^-1=0.5, 2^-2=0.25..

since anything to the power of 0 is 1 you can use this math function to compute any frequency if you know one, eg. 440 * (2^0) = 440, 440 * (2^-1) = 220 et c.

where the ET comes in is the division of the unit... 1/12 = 0.083333.. so one semitone above 440 is 440 * 2^1.083333, two semitones is 440 * 2^1.166666 et c.

switch to scientific view on your windows calculator and use the x^y button... eg. 2 [x^y] 1.1666666

LOL,

OMG, xoxos, you really live up to your signature (Mr Entertainment)...

Thanks for this. This formula will be hugely useful in CDP when I don't have my note to frequency chart handy (it's currently 500 miles away in a friend's loft).