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The crossover decides where your main speakers stop and the subwoofer takes over. Set it too low and you get a hole in the bass, or speakers straining at notes they can’t play. Set it too high and the sub starts to sound like it’s in the corner rather than part of the music. This tool finds the right frequency for your speakers and tells you exactly where to set it, for a home system or a car.
- Pick Home system or Car audio.
- Choose your speakers, or enter the low-frequency number from their spec sheet.
- Tell it what drives them: an AV receiver, a stereo amp or a soundbar.
- Follow the step-by-step settings under the result.
Quick reference
If you just want a starting point, these are the usual settings. The tool refines them for your speakers and how you listen.
| Main speakers | Typical crossover |
|---|---|
| Small satellites (2–3″ drivers) | 120–150 Hz |
| Soundbar | 100–120 Hz (often automatic) |
| Small bookshelf (4″ woofer) | 100–110 Hz |
| Bookshelf (5–5.25″ woofer) | 80–90 Hz |
| Large bookshelf (6.5″ woofer) | 70–80 Hz |
| In-wall or in-ceiling | 80–100 Hz |
| Floorstanders | 60–80 Hz |
| Car: 6.5″ door speakers | 80 Hz high-pass, 80 Hz sub low-pass |
How the finder works
Every speaker has a point where its bass starts to roll off, usually quoted as the −3 dB point. The crossover should sit a little above that, so the speakers hand over to the sub while they’re still playing at full strength. The finder takes your speakers’ roll-off, adds a margin (more for ported speakers, which fall away faster below their tuning), and rounds up to the settings receivers actually offer. For home theater it never recommends lower than 80 Hz, the THX standard, because it takes the hardest work off the amplifier and lets the sub be placed where the room sounds best. Spec sheets that only give a range, like “45 Hz – 25 kHz”, are usually quoted at −6 dB or lower, so the tool allows for that.
Crossover, LPF and the sub’s dial: what’s the difference?
- Crossover (receiver): the frequency where bass from your speakers is redirected to the sub. This is the setting that matters most.
- LPF for LFE (receiver): the upper limit for the separate movie bass channel. Leave it at 120 Hz.
- Low-pass dial (on the sub): only use it when there’s no receiver doing the job, such as with a stereo amp. With a receiver, turn it to maximum or set it to LFE or bypass so the two filters don’t stack.
Our guide to subwoofer crossover settings goes into more detail, including when to use “Large”.
Crossovers in a car
In a car the job is the same but the settings live in the head unit or amplifier. A high-pass filter on the door speakers stops deep bass reaching them, which is the biggest single cause of distortion and door rattles. A low-pass on the sub keeps it from playing vocals, and a subsonic filter protects a ported sub below its box tuning. Use the filters in either the head unit or the amp, not both. For more control, a car DSP such as the Dayton Audio DSP-408 adds steeper filters, EQ and time alignment.
Check it by ear
The number is a starting point; the room has the final say. Play our test tones around the crossover frequency and listen for a dip or a bump as the tone moves from the speakers to the sub. A dip usually means the sub and speakers are out of phase: try the sub’s phase switch, or work it out with our distance and phase calculator. A basic decibel meter makes this easier, and a UMIK-1 measurement mic with free REW software shows the whole picture.
Frequently asked questions
Is 80 Hz always the best crossover?
It’s the best default. THX chose it because it suits most speakers and keeps the sub hard to locate. Small speakers need higher, and big floorstanders can go a little lower, but plenty of people with large speakers still get smoother bass at 80 Hz.
Should I set my speakers to Large or Small?
Small, in almost every case. “Small” simply means the receiver sends the deepest bass to the sub. Large makes the speakers play everything, which only helps if they genuinely reach down to about 30 Hz and the sub is placed well.
Why did room correction set a different crossover?
Room correction measures each speaker’s roll-off in your room, which can differ from the spec sheet. If it picks something sensible, keep it. If it chooses very low, such as 40 Hz for bookshelf speakers, raise it to what this tool suggests.
Can the crossover be too high?
Yes. Above about 100 to 120 Hz you can start to hear where the sub is, and voices can sound like they come from the sub. If your speakers need a high crossover, keep the sub near them at the front of the room.
What crossover should I use with a stereo amp?
There’s no bass management, so the speakers play full range and the sub only fills in below them. Set the sub’s low-pass dial a little above the speakers’ roll-off, often 50 to 70 Hz for bookshelf speakers and floorstanders.
What slope should I use in a car?
24 dB per octave if you can choose. It keeps bass out of the doors more effectively than 12 dB per octave, so you can use a lower crossover point.