"HIS THEORY: The patches that are downloaded off of the net are made from the same waveforms that are already on the XP you have"
Correct, but what you are downloading is not the waveforms, but their arrangement in the patch; you're downloading the data that arrangings the patch's parameters, not the waveforms.
"They're just EFX'ed different and run through all the different filters on the XP to make their sounds unique
Essentially correct, though there's a lot more to programming a "unique" patch than just tweaking filters and changing the EFX. There are literally hundreds of parameters.
{As an aside: I don't think there are many genuinely "unique" patches out there on the net. Just my humble opinion.}
"and to make them sound like some of the patches off of the expansion boards."
Well, sometimes they sound "more" like sounds on the expansion boards, sometimes more like sounds in the presets. With many (probably most) expansion-board patches, it's impossible to recreate the expansion board patch using only the onboard waveforms.
"Hence, using a lot more of the XP's memory and power than if you were to just install the optional expansion boards."
Well, maybe, maybe not. A good patch is a good patch whether it comes from preset waveforms or from expansion-board waveforms; same for bad patches. Really, IMHO a "good" patch is one that addresses your needs.
BTW: It's not really "using more of the XP's memory," since memory has nothing to do with patch programming. Memory is for storage, not patch programming.
"The patches on the optional expansion boards are made from all NEW waveforms that are specific to each expansion board, and that get added to your XP only when you install those boards. When you take them out, the waveforms are no longer on your XP. (Which makes sense)"
And is essentially correct.
"You can't load waveforms into the User banks on the XP?
No.
"You can load patches into your user banks...but not waveforms?"
Correct. The USER memory is patch memory, not waveform ROM. The waveforms are burned into ROM.
"How could this be true if each patch is made of waveforms,"
Strictly speaking, each patch is made up of an arrangement of waveforms + all their parameter data; patches "make use" of waveforms, but the patch itself is just the data that composes those waveforms' parameters.
"and you are able to download the patches?"
You're not downloading waveforms; you're downloading the data the *uses* the waveforms on your XP. You're downloading the patch-parameter information.
"Aren't you able to create waveforms on the XP?"
Unequivocally: No.
"IF so...why wouldn't the Patches you download into your user banks that are supposedly Patches off of some of the expansion boards - why wouldn't they have the same waveforms as the ones on the expansion boards and sound the same?"
Because the waveforms the patch needs are on the expansion board, not on your keyboard UNLESS you have the same expansion board.
"When one person on their XP uses a sound off of one of their expansion boards to make a song, ... and then copies that song onto a disk to give to another person who also has an XP, but who does NOT have that same expansion board - the sound (patch) will not sound when the other person plays it on their board
That depends on how the sound is called up. If the person saved using Song + Sound, the patch simply won't appear because the expansion board (each of which has a sysex ID) is not there.
If the person saved the song using Song Only and is calling up patches using Bank Select messages (CC0, CC32, and PG), then the Bank Select messages will call up whichever patch is in *that* particular location on your keyboard. If you don't have the same expansion board in the same slot, a different patch will be called up.
"because they don't have that expansion board. Hence, they have to substitute the missing patch with a patch of their own."
Yes; but to do that, you have to call up that patch somehow first. But that's another story.
"But, downloading a song into the XP isn't the same as downloading a patch."
Well, yes and no. But for this discussion: No, it's not the same.
"WHen you download a song, the XP looks for that specific patch that you used in one of the expansion slots."
See above: What the XP actually looks for depends on how the song was saved and how the patches are being called up. A very important distinction.
"If they aren't there, the XP won't find that sound of course."
See above: *Or* the XP will go to the location designated by the Bank Select messages and find a different patch from the one it (the song, the part) is expecting.
Man, you've got some racy questions going these days. Are you sleeping well at night?
The XP can be a brain-bender, can't it?