I received the replacement Ghost Subs and did some testing this weekend. Keep in mind I have my ear right near the sub so these sounds may not be heard if sitting in the seat. I am also very sensitive to sound.
Troubleshooting: - Bass was set to flat on EQ and minus 2 clicks on the boost
1) Removed the metal grill from the rattling ghost subs and subs from the enclosure - the rattle persisted.
2) Tested the resistance of both the Ghost Subs in the vehicle as well as the new ones received - both measured 6.8 ohms (interesting as I thought they were 8 ohms but I guess they lowered the resistance to get louder sound like the Bimmertech subs).
3) Installed new subs - rattle persisted.
4) Tried a frequency generator - It seems the issue happens around 100-150 Hz . The bass gets sloppy and I get the rattling under the threshold (note: I have to get exact frequency as I was having CarPlay connectivity issues and a ran out of time).
5) Installed the factory sub and got a similar rattle/woofer muddiness on the same songs.
Findings:
1) I have come to the conclusion that the Ghost Subs (and factory) are just incapable of reproducing low bass frequencies below ~150hz (again, exact frequency TBD). They try but the sound falls apart.
2) As a result the bass becomes muddy/rattles the subs.
Proposed Solution:
1) I do like the mid bass punch of the Ghost Subs, so I was thinking of getting "
Bass Blockers" to filter out the low frequencies from the Ghost subs.
2) I intend to install a dedicated JL Audio 500/1 amp and HO 10" ported sub box which will fill in the filtered frequencies.
Other Options:
1) I wonder if I would have better luck with another OEM replacement sub? I am limited to 7-8 ohms so I think the only other is
Bimmertech AlphaOne.
For reference, I have an X3MC with the HK system.
Opinions appreciated 