LowerSpeed: 0.87 Hz
UpperSpeed: 1.11 Hz
Interesting. Is this an attempt to conceal looping? Or is it a way to make one string sound like three beating together? Applied independently (per note) with somewhat randomized settings that might work, but as a global in-line effect I'm not sure what this would do to an AP voice.
Im also curious about this.
Well since you've both asked, I'll give you a detailed explanation. But first, a bit about "Auto Pan" ...
Background: As its name implies, it's simply a way to move stereo (or even mono) sound from left to right (i.e., back and forth) without having your fingers on the "pan" knob.
If you have a strong effect and have it oscillate quickly, it's very spacey sounding ... a lot of electric piano sounds rely on this, kind of similar to a Leslie speaker system (iconic Hammond organ sound).
If you have a weak effect and do it very slowly, the result can be so subtle as being hard to even detect. At around one oscillation per second (which is what a frequency of roughly 1 Hz means, i.e., 1x per second) you're in the range of timing ("frequency") that's not unlike what your brain interprets as ambient echo (sound reflecting off of walls, studio surfaces, etc.)
But the brain will interpret this as such only if the effect is very gentle - just a little oscillation of where the sound direction is a bit stronger vs weaker following the initial primary note sound.
Again, if it's too strong or too frequent (higher timing settings) then it's just another kind of vibrato style effect, which makes little acoustic sense for a natural sounding grand piano.
My particular settings:
LowerSpeed: 0.87 Hz
UpperSpeed: 1.11 Hz
2-Band means that the autopan effect is applied at 2 different speeds (Lower and Upper) where one speed of panning is applied to somewhat lower piano notes vs the higher ones. I've selected 675Hz as the note frequency - meaning the PITCH of the notes (NOT to be confused with the speed of the panning back and forth, which unfortunately is also referred to here as "frequency") - to split my "higher" notes and "lower" notes. This falls somewhere in the middle range of the keyboard (remember an A is a 440 HZ wave freq.)
In other words, I want the higher notes above 675Hz to pan (echo) a little more quickly at 1.11 times per second, than the lower notes, set at 0.87 times per second. Rationale: I believe that higher notes arriving slightly sooner intensifies the (psycho-)acoustic echo effect, at least as the brain interprets it. I don't know where this is based on science or mumbo-jumbo, but it just sounds better to my ears.
The balance @ 64 simply means (from between 0-127) I'm not biasing the stereo either way ... it's split down the middle or center.
Perhaps most importantly, the depth is set to only 10 - which is a fairly LOW AMOUNT of effect. A little bit higher and it gets tiring on the ears/brain after while. Too much more beyond that and it's just plain weird from the outset.
The point of all this:
This AutoPan setting tricks my brain/ear into hearing a very subtle touch of "richness" to the acoustic piano sound ... when listening in stereo (in mono, panning is basically pointless) this effect gently reinforces the sensation that the piano sound is more fully "filling" the room or stage. It makes the piano sound "come alive" just a pinch without one being able to quite puts one's finger (ear?) on why it's more complete.
This effect works nicely with other acoustic natural instrument sounds, like woodwinds, solo strings, quitar, banjo, acoustic jazz drumkit, even human voices.
Simple experiment suggestion: Dial in these settings (or ones you prefer) and then push the button on the MP's EFX on and off to see which you prefer (i.e., an "A/B" test).
This effect is best experienced through stereo headphones, but stereo speakers will likely give a comparable change in sound too.
For learning purposes, you might try overdoing this effect (simply raise the depth to a much higher level) just so you can more clearly hear what is going on.
But for me, once your ear can directly hear the effect itself instead of the underlying piano sound being the focus, it becomes too obvious - and then it becomes really annoying and distracting instead of a gentle reinforcement of space.
@dewster: With due respect, using autopan in this way is notintended to conceal anything ... on the contrary, it's intended to make the sampled piano sound slightly more noticeable
Hopefully some of this is helpful! - OneWatt