Anyone know why my speakers don't sound right?

[__________________zb]

I have a 2011 polo SEL, with front and rear speakers, all of which have been upgraded.

For some reason, the rear speakers sound like they have some kind of low pass filter and not playing the high frequencies, although they are 2 way speakers with tweeters. I don't know if this is an issue with the head unit or wiring or maybe there's a crossover somewhere?

Also, the front left speaker has a similar issue but also has some crackling sounds at all volumes. Maybe it's blown?

Any help would be appreciated as i have no idea why speakers sound like that!

[Aquavalver]

Personally I'd go to a proper car audio specialist. It might cost a bit more, but at least they should know what they are doing and sort your problem out!