Sub crossover and level
Where the speakers run out of steam, the sub takes over. Slope tells you where to start and whether the sub is too loud or too quiet.
What the crossover does
The crossover is the frequency that splits the work: below it the subwoofer plays, above it the speakers. Set too low, it leaves an uncovered band between the two curves; set too high, the sub plays notes you can hear coming from it.
Where you set it depends on your system: in the speaker menu of your AV receiver, if the amplifier manages the crossover, or with the knob on the sub, if the speakers get the full range. In the results, the card is called Amplifier crossover or Subwoofer crossover accordingly.
How Slope picks the value
Slope looks at where the speaker curve starts to drop, the −3 dB point, and how steep the drop is. From there it suggests a value to try, such as “Try about 80 Hz”, and a range.
It's a starting point, not an exact value. Use the setting available on your system closest to the advice, then check how sub and speakers play together with the Summation check. Crossover details shows the values the advice is based on.
Enter the crossover you set
Slope can't read the value from your system. On the crossover card, in the Set on the sub row, tap Edit and enter the frequency you actually use. The mark on the graph, the Summation check and the PDF summary will then follow that frequency instead of the advice.
The sub's level
The Level check compares the sub with the speakers. A positive number means the sub plays louder, a negative one that it plays quieter.
It's a rough estimate: differences of 1–2 dB don't matter, and you don't need to reach 0. If the sub is clearly above or below, the Suggestions tell you how much to adjust it, usually a little, 2–3 dB at a time.
In the Guided session you can change only the sub's gain and tap Measure the sub again, without measuring the speakers again. Then listen: if you like a bit more bass, that's fine. Slope suggests, you decide.