Only Effects are Hard Limiter and SC4

I have recorded some audio within Audacity. Then, I press command+a to eliminate all the background sounds, but the only effects that aren’t faded out are the Hard Limiter and SC4. Then, I only selected 5 seconds of my recording, yet, the same result. All I have done is installed Audacity. Do I need to install something else too?

In Audacity versions up to and including the current 2.1.2 version, playback must be “stopped” (not just “paused”) in order to apply effects.
The exception to this rule is effects that have “real-time preview”. This includes LADSPA effects (such as Hard Limiter and SC4) and VST effects (Audacity does not currently ship any VST effects).

To use any other effects, you must “Stop” playback before you can use the effect (click the Stop button).

In the next version of Audacity (2.1.3) there are a few more “real-time preview” effects.
For more information about “real-time preview”, see here in the manual:

Also in Audacity 2.1.3, the other effects are not greyed out. Selecting an effect automatically stops playback.

Also in Audacity 2.1.3, the “Hard Limiter” effect has been discontinued and is replaced by a new “Distortion” effect, which includes settings that produce an identical effect to the old Hard Limiter. The “Hard Limiter” effect is not recommended as a “Limiter” because it creates distortion. If you require a proper “Limiter” effect, use the “Limiter” instead (

Audacity 2.1.3 is currently undergoing testing in readiness for imminent release. (It will be announced on this forum and on the Audacity website, facebook and twitter when the new version is available).

Actually in 2.1.3 selecting an effect does not stop playback (or recording).

What it does do is to over-ride the Pause if you have paused while playing and implement the effect on the selected audio (this little glitch has confused may users for many many years - even catches out Audacity veterans sometimes - even me … ).

The effects are still grayed out while recording so making a selection and trying to choose an effect while recording will NOT stop or interrupt the recording.