This is probably a dumb question but here it goes. I have a GB25 that is making a “zipping” noise when doing the REW sweep, more at the lower end of the band pass (200-3500Hz). I thought I had another rattle in my left door panel and then I realized it was actually coming from the GB25. I thought the grille was rattling but it still does it with no grille. I pulled my other a-pillar out and plugged that side in to the left and it doesn’t do it so I know it isn’t the amp, DSP, or wiring to the a-pillar. I removed the speaker and reseated the wires since I had a poor connection cause an issue in my truck and that didn’t change anything either. Unfortunately, I bought these second hand so I have no warranty. I Was about to pull the trigger on a new set and these popped up, they were sold as new only pulled one out to see it didn’t fit. So unless one of us damaged the speaker handling it accidentally, I think it’s blown. I was just curious if that’s the normal noise it makes when they get blown (if there is a normal noise). My pods are from Printed Acoustics so they aren’t metal and I used the foam gasket between the speaker and pod. I was thinking about putting a little poly fill behind the speaker just to see if that changed anything.