I honestly don't know many 'communities' but Vintage Synth [1] is great. It's hard to avoid Gearslutz, you'll see it googling. Hydrogen Audio [2] is one of the better music communities I know, apart from Jemsite, but it's mostly digital/software/algorithm stuff. Maybe Future Producers [3] is more your thing. Or check synth-specific forums (I don't know what you've got). [4,5]
[1] http://www.vintagesynth.com
[2] http://www.hydrogenaud.io/forums/
[3] http://www.futureproducers.com/forums/
[4] http://forum.moogmusic.com/viewforum.php?f=12
[5] http://www.dsiforum.com
