The internal modifiers are not very difficult to use (except perhaps the ADSR), but they are tedious to edit because you must both program the modifier, the effect and the Link response curve, not to mention moving between the different menus repeatedly.
The Pitch Detector
The Pitch Detector determines the pitch of sounds entering the G-Force. Like the Pitch Shift effects it can't interpret chords very well, only single notes, which limits its usability. From software version 2.00 the Pitch Detector uses one detection range for bass and one slightly higher for guitar, from software version 2.03 there's also one for seven string guitars.
The Envelope Follower
The Envelope Follower detects the level of sounds entering the G-Force. You can set the amount of lag before and after the guitar level changes both in the Envelope Follower itself and by editing the Glide Time parameter in a Link response curve. Note that distorted preamp sounds are more or less compressed, which also reduces the effective range of the envelope follower. It's important to keep the G-Force input at the same level as when you edited the Envelope Follower (see the page on levels).
LFO is short for Low Frequency Oscillator (a device that creates slow cycles), a component that's used in synthezisers, tremolos, panners, phasers and chorus/flanger effects. Even in G-Force effects that already use an internal LFO you can still link an LFO modifier to their Speed parameters, which will result in accelerating/decelerating speeds.
When recalling an LFO-modified effect you cannot know were in its cycle the LFO phase is, which adds an element of randomness. One way to avoid this is to make an ADSR behave like an LFO instead.
From software version 1.12 all LFOs in the G-Force can be turned off. This can be useful during editing, if you have linked an LFO to an effect parameter and wish to temporarily "bypass" the LFO from the effect without deleting its Modifier Matrix link.
vibrato effects (using any pitch shift parameter).
The ADSR
ADSR means Attack Decay Sustain Release. Like LFOs it's a feature often found in synthezisers. For the ADSR to trig properly you must keep the relation between the G-Force input level and the Threshold parameter the same as when you programmed the effect (see the page on setting global and effect levels, and below).
The ADSR sequence
The Threshold parameter controls how sensitive the ADSR should be: when the G-Force input signal exceeds the Threshold level the ADSR sequence is triggered. Only the input signal and the Input Level knob on the front panel affect this, not the Gate, so even if the Gate would mute the guitar signal completely the ADSR Threshold can still monitor it.
When the ADSR is triggered it will perform something like the following sequence (depending on trig Mode), which can be viewed in a Link response curve:
Go from min to max "level" (note that we are not talking about sound level here). This is shown in the Modifier Matrix by the marker moving from hard left to hard right. The time this takes is set with the Attack parameter.
Fall from max level to the Sustain level ("Sus-level"). The time this takes is set with the Decay parameter.
Stay at Sustain level during the Sustain time, which is shown in the Link response curve by the marker resting at some point (where it comes to rest depends on Sustain level, how long it rests depends on Sustain time).
Fall from Sustain level down to min level. The time this takes is set in Release, and is shown by the marker returning to its min position (hard left in the Link response curve).
The ADSR trig modes
The behaviors of the ADSR trig modes are a bit hard to understand, but this is how I believe they work:
Once means that the ADSR sequence described above will run only once. After that the audio signal into the G-Force must fall below the Threshold level before the ADSR can be trigged again. Even if the signal falls below Threshold during the ADSR sequence and again exceeds it the ADSR will keep playing its sequence to the end before it can restart.
Once retrig means that the ADSR sequence can be interrupted and restarted if the input signal falls below Threshold and again exceeds it.
Loop means that the ADSR sequence will keep repeating its sequence as long as the input signal stays above Threshold. When it falls below the Threshold, the ADSR sequence finishes its current sequence and then stops.
Loop retrig also means that it will keep repeating but can be restarted in the middle of a sequence before it has finished.
Sustain means that it will stay at Sustain level for as long as the Input level stays above Threshold. The Sustain time parameter is not used. When the Input level drops below Threshold the ADSR will finish its sequence, after which it can be restarted.
Sustain retrig works like Sustain but can be restarted in the middle of a sequence if the input level falls below Threshold and comes up before the ADSR sequence has finished.
General tips and limitations
Since an ADSR is always triggered by the Input level, it's very important that its Threshold level is matched carefully or the ADSR will trig too easily or not at all.
The Input level must reach above the Threshold level to make it trig and then fall below to either finish the sequence or to make it possible to retrig the ADSR. Because of this it can be a good idea to have as big level differences as possible between sound/no sound at the G-Force input. Clean preamp sounds may trig more reliably than distorted, since the latter are usually compressed and noisy. Note that the Gate can not be used for this, since the Gate doesn't the ADSRs.
There seems to be a short delay before the input level detector in the ADSR reacts to level changes. Because of this the ADSR may not have time to trig/retrig if you're playing fast.
Ways of using the ADSR
The ADSR can be made to work in ways similar to both the Envelope follower and the LFO.
Like the Envelope follower it reacts to changes in the input level, the difference is that the ADSR can only react in two ways to the input level (trig or not trig) while the Envelope follower follows the input level smoothly.
Like the LFO it performs a looped sequence, with the differences that it
can be triggered
makes a more complicated loop
always start from the beginning, while an LFO just keeps going and therefore starts at random when recalled.
Things you can do with the ADSR
A gated Reverb can be made by choosing Sustain trig mode, setting the Decay and Release times to min and link the ADSR to a Reverb Level parameter. The Reverb Level will stay high as long as the input level into the G-Force stays above the Threshold level. The Reverb tail must of course be sufficiently long as well. By increasing the ADSR Attack time you can make the reverb fade in slowly, which may sound similar to a reverse reverb.
An LFO that you can trig, and that always starts at the same position in its cycle (see the page on making an ADSR work like an LFO for details). This way you can make tremolos or an auto panners that always begin in known positions.
An Envelope follower that always performs the same sequence, no matter how soft or hard you play your guitar (provided that the ADSR trigs properly). This includes sophisticated auto whammy effects (when linked to a pitch parameter), ducking delays or touch-wahs.