midi instruments sounds dreadful

[hootist]

just reinstalled osx Yosemite to fix one problem now find that protools works but the sound from midi instruments are dreadful with loads of distortion wobble and the like.

The same happens in logic pro x

Model Name: iMac
Model Identifier: iMac13,1
Processor Name: Intel Core i5
Processor Speed: 2.9 GHz
Number of Processors: 1
Total Number of Cores: 4
L2 Cache (per Core): 256 KB
L3 Cache: 6 MB
Memory: 8 GB
Boot ROM Version: IM131.010A.B09
SMC Version (system): 2.9f5


soundcard presonus 1818vsl

[musicman691]

What vi's are you using? You don't say.
It could be anything from level issues to a corrupted install of the vi's to who knows what. Maybe you can post a sound sample of what you're talking about. Could even be your hardware and it's setup. The vi's you're using - samplers or something else?