I never heard of this one. Thanks to Björn Arlt at Full Bucket Music, you can pick up a free copy of the FB-3300, a soft synth based on the rare KORG PS-3300 polyphonic analog synthesizer from the late seventies.
About the Korg PS-3300
Here's a little history about the vintage synth, taken from the manual that comes with the download:
In 1977, KORG released two new synthesizers, the PS-3100, and the PS-3300, where “PS” is short for Polyphonic Synthesizer.
By that time not many polyphonic synthesizers were around, and being even fully polyphonic the PS brothers (in close approximation the PS-3300 consists of three PS-3100) were propelled into the noble company of a Polymoog.
While the PS-3100 is a rather modest instrument, the PS-3300 features no less than 3 independent synthesizer blocks (comparable to almost a full PS-3100).
Each block has 48 voices with 48 filters and 48 envelopes, but only 12 oscillators generate the top octave frequencies for the twelve keys C to B. The remaining 36 signals are derived by frequency division, but the PS-3300 is not just a sophisticated organ.
The PS-3300 is huge.
Back to the seventies we go...
The user manual provides more information about the synth's architecture, its signal generators, filter section, envelope modifiers, and more.
How to Install the FB-3300
Just copy the FB3300.component and fb3300.ini files from the ZIP archive you have downloaded to your standard macOS Audio Unit plug-in folder:
Logic Pro should automatically register the FB-3300 AU plug-in the next time you launch it.
If it is not showing up in Logic Pro, try restarting your Mac.
That did the trick for me (I'm running macOS High Sierra on my 2015 Macbook Pro).
Both 32 and 64-bit versions are available.
Should work for Logic Pro 9 geezers too then, I suppose.