Thank you for your time Christoph. I think this sound must be one I created and then forgot about. I cannot find it anywhere on my computer, so do you know where these kinds of user created files are stored? It is a software instrument, and I'm sure it's a variation of one of the standard software instruments.
I am hoping to find the file so I can transfer it to my other computer.
I am trying to find the sound "Ambient Synth Piano"
This instrument is part of the instruments that came with JamPack 1.
It uses the Grand Piano+Pad.pst
/Library/Application Support/GarageBand/Instrument Library/Plug-In Settings/Piano/Grand Piano+Pad.pst
Do you have the JamPacks installed on all your Macs?
The settings in the "Edit" pane are like this:
Thanks Léonie. I do have Jam Pack One on the computer, but what I can't figure out is why it isn't on my other computers. They are newer computers and I did the suggested downloads, but they don't have Jam Pack One. Has Apple stopped supporting the Jam Packs? I couldn't find it in the Apple Store or any significant information at Apple Support.
The JamPacks are no longer sold separately, and they are not part of the additional GarageBand contents. And not all of the old installer CDs for JamPacks work with Mt. Lion, some installers use PowerPC code.
What I have done, is buy MainStage 2 from the App Store. It will install all five JamPacks in the same location where GarageBand is looking for the JamPacks. So by installing MainStage you will be able to use them in GarageBand as well, without any special setup for GarageBand. The price for MainStage 2 is moderate - about 30$ for all five JamPacks. I found it less trouble to invest in that than trying to migrate the old library files from old my Mac. Christoph may be able to help with that - I think he just recently migrated the JamPacks.