Using the DualVerb algorithm is one way to ‘split the FREEZE’. Two independent reverb drones; separated into higher and lower EQ focus here. The HotSwitch shifts both A-DECAY and B-DECAY from 4 BAR to FREEZE. The expression pedal ‘bends pitch’ for the lower frequency drone [Reverb B] by changing the SIZE of only one reverb. This ‘pitch bend’ works with either the default DECAY(s), or on the droning FREEZE, while the higher frequencies [Reverb A] pass through (relatively) unaffected.
And then there’s the most mentioned algorithm: ModEchoVerb. It’s capable of many types of effects. But it also offers two choices for infinite hold [DECAY, and ECHO_FDBK], that can be mixed together. This preset starts at an INF default, and can be HotSwitch’ed to 5.00 DECAY time. It’s a reversed approach: one that begins with an infinite drone, and fades out when switched ‘ON’.
The expression pedal takes the single 1.5 second ECHO, and sweeps it to infinite ECHO-FDBK . At the same time, FLANGR MIX sweeps from 0-100 to introduce deep modulation. Blending HotSwitch & expression pedal positions will combine or separate these two independent ‘drone’ types.