- Open Options->Preferences->BPM Detection
- Create or edit a BPM scheme with the range you want & click OK.
- Highlight that scheme in the list.
- Click the "Default" button. (It's only by doing this that the selected BPM scheme is activated.)
- Go analyze a new track and see if the BPM is correct.
We hope to make this automatic and more intuitive in a future version of Mixxx.