low sub sound when driving? Sounds fine when parked

[Jacobwatersx]

Installed a sub last last week, sounds really good until I start driving, then sound goes noticeably quieter than idle or aux, any idea what it could be? (Had battery tested it’s fine)
Power is wired to last post on battery fuse box.
Any ideas? Thanks

 

[NHN]

Does it have Bose?

 

[SootySport]

That's normal due to engine and road noise. Bass and treble seem to reduce in volum.e when driving,. Older head units had a 'Loud' switch to compensate this effect but newr head units have other fancy terms.

 

[Jacobwatersx]

Does it have Bose?

No it’s only front speakers non Bose, all the regular speakers work fine it’s only the sub that’s going quiet.

 

[Jacobwatersx]

That's normal due to engine and road noise. Bass and treble seem to reduce in volum.e when driving,. Older head units had a 'Loud' switch to compensate this effect but newr head units have other fancy terms.

I’m pretty sure it’s not that, as soon as I start moving the bass noticeably dips as if it’s getting less power, I haven’t had this in previous cars and engines on those where a lot louder. Weird

 

[NHN]

Which head unit is fitted?

 

[Jacobwatersx]

Which head unit is fitted?

It’s a newish sony headunit, i know for sure it’s not headunit related and I plugged the sub into my phone with an adapter and the same problem happened.