Is there a plugin that suppresses the frequency below a threshold?

[pluginnow]

Here's the proper link

https://github.com/timsainb/noisereduce/

Would certainly try it, if VST.

[Funky40]

There's also this, works as a spectral expander...
http://www.proaudiodsp.com/
But the price isn't as good as the sound hack stuff. Worth a look

worth to mention:
this one is *right now* on sale at PA for $29.99

https://www.plugin-alliance.com/en/prod ... sm_v3.html