Three boxes you own
- The rack, and back
replaces the desk with a rack, master column and all. There is nothing to mix towards while you are setting up a box, and half a desk behind it would only be in the way. again leaves the desk exactly as you left it.
A rack unit is not a section. A section is on every strip. A unit is one box, patched onto one strip at a time. The day there are four units there will be four boxes, never a fifth compressor on every channel. The desk already has one of those.
The whole rack is on every desk, Studio or not.
Patching
Where a unit is patched sits above the faceplate, not on it: it is not one of the box's settings, and you move it from the snare to the vocal without touching a knob.
Two points, and no more: PRE EQ or POST EQ on that strip. A low cut ahead of a compressor stops the bottom end driving the gain reduction, and that is the one difference worth a choice. Both points are ahead of the gates, and the fader stays downstream of everything.
Patched and switched in are two different things. The slot says where, the IN/OUT button says whether, so you can A/B without losing the patching. A bus takes a unit as readily as a track.
FET-A
A fast compressor with no threshold knob, and that is the box: you drive it with INPUT, the threshold sits where it sits, and OUTPUT brings the level back.
Its ratio switch does not behave like a number line. The threshold climbs with the ratio, so a lower ratio can give more gain reduction at the same level, and ALL is the deepest position rather than the steepest. It gets there by starting earliest. That is measured, not a fault to work around.
LA-2A
The opposite kind of compressor, and the reason to have it: it levels where the other two grab. Two knobs and a switch: PEAK REDUCTION, GAIN, and COMP/LIMIT. There is no ratio, no attack and no release, because there is nothing in the box that could have them.
PEAK REDUCTION writes the threshold it is actually setting beside the knob's own number. Its gain reduction is drawn on a 40 dB scale, because this one is routinely used at ten or fifteen where a fast compressor sits at three.
CHORUS
A stereo chorus, with a width meter on the panel where the compressors have their gain reduction. It is there because the ear cannot judge this one: the width is strongly frequency-dependent, so a bass with the low cut closed reads nearly mono however wet it is, and winding the cut up is what opens it.
If you want it on everything
Then it is not a job for the rack. Put the strips on a bus and patch the box onto that, or use the compressor every channel already has.