Gyraf Audio Gyratec XXIII (G23)
Stereo Tilt Equaliser
"Ambler" Tilt Equalizer
The G23 is a Tilt-type Equaliser aimed mainly at mix and mastering - for the situations where you have a mix that is already nearly-perfect balanced, but you want it a tad darker or brighter without messing up the overall definition.
Gentleness and subtlety were main design targets here: Nothing anywhere near surgical: Tilt and Highs at +/-4dB, mids at +/-2dB, and lows at +/-6.5dB
What sets it apart from all other tilt EQ designs is that we designed it around a highly linear 1dB/oct slope filter, so that rotating the tilt control will tilt an almost ruler-straight response curve, to a maximum steepness of 1dB/Oct.
Our reason for doing it like this is that although a standard tilt (which is basically a Baxandall control, that cuts top while boosting low and the other way around) does come with the associated phase roll that is a side effect of all analogue-domain filters. And this group delay/phase roll (which is distributed just around cutoff frequency) easily identifies the sound to our ears as "equalised".
So what we achieve in the 1dB/Oct tilt function is to "spread out" or distribute the "needed" phase roll across the whole spectrum, meaning that at any given interval, only minute amounts of group delay is apparent. In total, it allows quite some correction without sounding "Eq'ed".
And because you'd occasionally want to correct outer ends of spectrum, we have added a gentle Baxandall tone control, shelving lows and highs, wide-Q bell mid, each at three selectable frequencies, that we spent quite some time optimising.
G23 is stereo, single set of controls - and off course based on tubes and passives alone. Bypass is full-relay, and it has a gain trim function for easing comparison between direct and processed material.