Hey, I am using Renoise on a Mac.
I am aware that AU plugins are made for mac, and I heard VST is not compatible with mac, so when I download anything I make sure it´s an AU and not VST or something else.
But I once downloaded a VST by error… And it somehow worked, so I started downloading some more VSTs but none of them others were working…
So, what´s with the Mac and VST compatibility? How can I know if they will work or not?
I searched for this in the forum but did not find anything.
There is much confusion when it comes to Macintosh VST/VSTi due to the history of the mac platform.
First, Mac supports both VST and AU.
Up until 2006 all Macintosh were built using PowerPC processors. If you have a G4 or G5 then you have a PowerPC. Nowadays, all Macintosh computers are built using Intel x86 processors.
A lot of old Plug-ins were made before 2006 and never updated. These plug-ins are known as PowerPC specific. These old plug-ins will only work on a G4 or a G5. They will not work on newer Intel Macs.
Universal binary Plug-ins are compiled in a special way which allow them to operate on both PowerPC and Intel Macs. The symbol used to indicate this feature is the Yin-Yang. These types of plug-ins work on all Macs.
As PowerPC dies out, Macintosh Plug-ins are expected to become Intel Only. These newer Plug-ins will not work on PowerPC machines.
You, probably being a new mac user, must look for Universal Binary or Intel plug-ins.
And if I may just add to Conner_Bw’s excellent explanation,
make sure when you are searching for VST plugins that it says it is for a Mac.
Then make sure it is for your type of Mac as Conner_Bw has explained.
If it doesn’t say whether it’s for Windows or Mac, it’s usually for Windows only.
It’s important to note that VST is just a standard that defines a set of functions and methods for audio hosts and plug-ins to interact with each other. You can have VST plug-ins for Windows, Mac and Linux, but they are not necessarily interchangeable due to their different binary formats. A Windows VST will not (usually) work on a Mac, for example, and vice versa. The VST plug-in must be programmed and compiled specially for each operating system, and in some cases for specific CPU architectures as Conner has pointed out.
So the first thing to do is make sure you are indeed trying to use a VST that has been compiled for your specific type of Mac computer, rather than for Windows or something like that.
Edit: dformd beat me to the punch 
Yeah, my favorite VST (for Mac) at the moment is TAL-Elek7ro-II. A free instrument VST. Sorry, don’t remember where I got it, but a Goooooogle surely will do the trick. 
I got this one yesterday, but as an AU But thanks for sharing!
For the reasons everyone else explained, use VST’s for competitions that allow plugins, so then there won’t be complaints for not being able to run the dll’s or au’s.
Btw.
i switch to mac too. What do you, guys recommend - vst or au
thanks in advance
VST has been around a lot longer than AU, so it is more commonly available (and possibly more stable because developers understand it a bit better?). You will find that quite a few AU plugins are really just VSTs that are wrapped inside an AU container/shell, because it can save the developer some time doing things this way. Most of the time it doesn’t make much difference, and you can just use whatever you prefer, but it’s something to keep in mind I suppose.
I didnt know about that, now i have to rethink my workflow. What about big, expensive plugs (alchemy, reaktor, guru, t-racks 3), do they use the same tricks? Ive abandon most vsts when i had troubles with Ohmicide vst - when i changed the presets, renoise was freezing for few seconds if i didnt turn off meter inside the Ohmicide.
Thanks for tips
Well obviously I can’t really speak for what any particular developers or companies are doing, I can just say that such things do exist, and that in many cases it makes sense for developers to take advantage of it. VST and AU both offer some slightly different features, with different pros and cons, but most developers who offer their product for each format are only taking advantage of the lowest common denominator. They want their products to behave in exactly the same way whether it’s a Windows VST, a Mac VST, or a Mac AU, so feature-wise each version will probably be almost identical, and there is no huge advantage to using one or the other. Either way, even if the AU version is just a wrapped VST, you probably won’t notice much of a performance difference, so it’s nothing to worry about too much.
Of course - thank you for answers.