Many of the A-side or B-side parameters interact to an extent, so it’s helpful to isolate one or the other while adjusting the controls. For example, set the MIX to taste, set the ABMIX to A10 + B0, then concentrate on the A-side settings. DUAL MONO is just that: REVERB A on the left, REVERB B on the right, and no stereo interaction between them.
A-DECAY (B-DECAY) How long it’s going to take the main reverb tail to drop from the loudest point, down to inaudible (typical background noise levels) . You might see RT60 or reverbation time used on other reverbs; it’s the same thing. The ‘real world’ range goes from 0 to 50 seconds, but an INF setting never decays (in theory). FREEZE takes whatever is currently in the delay memory buffer, and sustains that indefinitely.
SIZE It’d be overly simplistic to describe this parameter as the length, width, and height of the reverberent space [room / hall / plate / cavern]. It’s one control, covering a variety of enclosed spaces (in both reverbs here). I’m hearing changes to the reverb shape & spread (buildup of the reverb attack, and length of the sustain segment) as well. Diffusion (smoothing of the reflections), the density between reflections, and the character of DECAY also seem to be scaled with is parameter.
So SIZE covers many reverb parameters in one place. The A-side and B-side reverbs can both be small to huge, or any combination between them. In the natural world, a small enclosed space would match a short DECAY with a small SIZE. But the independent controls allow creative combinations, like a an aircraft hanger SIZE paired with a very short DECAY.
A-PREDELAY (B-PREDELAY) It’s a cheat parameter, but your ears are easily fooled. This is just a delay in time before the wet reverb kicks in. No different than any other echo or delay, but placed just before the reverb section. It’s very useful for separating the dry signal from the point where the reverb kicks in.
Reverb can easily swallow up the original input; blurring the distinction, and smearing everything together. Pre-delay can be in actual time (instant, to just under one second). Or you can sync it to tempo for a more modern, rhythmic effect. A-DECAY (/B-DECAY) will also be confined to a beat / measure increment [1/8th note to 10 bars long] in TEMPO mode.
RESONANCE (A-TONE / B-TONE) Any reverb will delay a portion of your input signal, and feed it back into the input. Resonance is similar; it causes a buildup of levels around a much narrower frequency range. It can simulate the vibrations that you get from different materials in the enclosed space. Focused areas of the frequency spectrum are reinforced or removed, and adjusted with the A-TONE and B-TONE controls. And RESONANCE is the sub-mixer for tone parameters.
The best way to hear the RESONANCE effect is to approach it like you would an equalizer. Isolate just one of the ‘verbs with ABMIX, and set it’s DECAY to a healthy amount (or INF). Then set RESONANCE to midpoint, and adjust the A-TONE (or B-TONE) parameter. Once you’ve found the resonant frequency range that you’re after, dial down the RESONANCE mix to the appropriate level of influence.
One thing that may not be as apparent is that the “TYPE” parameter – often a labeled control in other units – is covered by separate algorithms in the H9 / SPACE. The choice of HALL, ROOM, PLATE, etc. is going to have a huge influence on how common reverb controls react. The adjustment of DECAY and SIZE will still mean the same thing, but the algorithm itself will determine the core ranges, proportions, and unique characteristics.
