2024 Crosstrek Subwoofer Not Giving Me Any Bass Below 40Hz… Any Ideas?

Hey everyone,

I recently had an underseat sub installed in my 2024 Subaru Crosstrek. I thought the sub would help me hear some low-end bass, but I still can’t hear anything below about 35-40 Hz. The sub is definitely working, but it just doesn’t seem to produce anything lower than that threshold.

I’m not really experienced with car audio. Does anyone have any idea what could be causing this? It feels like the head unit isn’t outputting frequencies below that range, maybe to protect the stock speakers. Now that I have the sub, is there any way to make the head unit send those low signals to the sub? Do I need an amp for the sub, or is the powered one I have enough?

You probably won’t get much output in that frequency range with an under-seat subwoofer.

Kiran said:
You probably won’t get much output in that frequency range with an under-seat subwoofer.

When you say ‘not much output,’ do you mean I won’t hear anything at low levels? I’m not trying to get a super heavy bass sound, I just want to hear the full range of the music.

@Poe
Check the frequency range of the sub you’ve got.

In my opinion, you’re not going to get much under 40Hz with a sub small enough to fit under the seat.

Kiran said:
@Poe
Check the frequency range of the sub you’ve got.

In my opinion, you’re not going to get much under 40Hz with a sub small enough to fit under the seat.

The sub is rated to go down to 20Hz. When I test the low frequencies, it seems to cut off right around 35Hz. It’s a 10-inch sub.

I’ll talk to the shop where I had the sub installed and see if they have any suggestions. I also need to look into line-out converters.

Kiran said:
@Poe
Check the frequency range of the sub you’ve got.

In my opinion, you’re not going to get much under 40Hz with a sub small enough to fit under the seat.

I agree with this. I tried fitting two subs under the second row of seats in my 04 Tahoe. The only prefab sealed box that fit under there could only hold 8-inch subs. After testing with WinISD, I realized the subs hit their maximum excursion at 60Hz. The setup was never going to provide good bass.

I found a bigger enclosure that fits behind the 3rd row, and it works great with up to three 12s. That setup can go really low. For your car, a decent-sized box with a 12-inch sub would likely work better and give you the low-end bass you’re looking for.

It’s likely a mix of having an underseat sub and the factory bass roll-off.

Paxton said:
It’s likely a mix of having an underseat sub and the factory bass roll-off.

Is there a way to get around the factory bass roll-off? This might be the issue.

Poe said:

Paxton said:
It’s likely a mix of having an underseat sub and the factory bass roll-off.

Is there a way to get around the factory bass roll-off? This might be the issue.

You should try a good line-out converter like the LC2i or KEYLOC.

For bass to sound good, you need the space to make it. A cheap plastic box isn’t going to cut it. A proper box in the trunk will give you the bass you want.

@Rylan
Thanks for the tip, I’ll check out those line-out converters.

The sub I have is a 10-inch, and the housing is way bigger than a cereal box, haha. It should definitely be able to produce sounds below 40Hz, and I don’t need them to be super loud. I rarely turn the volume past a quarter power.