This pack is actually part 2 of the Modular Samples Roland Jupiter 4 collection. Get the first part here.
On the surface, it seems like a pretty simple synthesizer, with just one oscillator, one LFO and 2 envelopes, however, in this case the whole is definitely greater than the sum of its parts. The Jupiter 4 has a massive tonal range all considered.
Not a lot of Jupiter 4 samples yet as it’s hard to sample with out midi or cv/gate control (I use Autosampler to cheat at making samples. You too could have a cool samples website, check it out http://www.redmatica.com). Still, I reckon you’ll find something useful here.
Btw, make sure you check out the whole Modular Samples website since it is a true goldmine of free vintage synthesizer samples. It’s a rather new resource (seems like the website was launched in November 2010) and I haven’t seen it mentioned a lot around the web. Let’s hope they don’t get bandwidth problems when the bpb crew starts downloading. ^^