I've just upgraded the stereo in my ute from the factory double din unit to a single din Clarion CZ202A head unit. It works extremely well and gives excellent sound even through the factory front and rear speakers.
Now, Problem is that upon turning on and turning off the stereo there is a loud sound that comes through the speakers. Unsure how best to describe the sound but it's like bang as if someone is flicking the speakers with their fingers. It's only one very short sound but it's loud and it is the same no matter what volume the stereo is on. It only happens as soon as you turn it on and turn it off. Anyone know what it might be? Need to upgrade the speakers perhaps?

Do you run an amp by chance?

If so check the ground on it is good. Since you haven't had the problem prior to installing the new headunit id check the ground on that too. But from memory of the days where i had a decent sound system it was caused by bad ground on amp.

I'm not even close to very knowledgeable on the subject, Just from my experience with this sorta issue.

It turned out to be a faulty head unit...It made the speakers pop loudly when you turned it on and off. The bloke at Autobarn exchanged it for another one and now it's all good.

Glad to hear you got it sorted.. Was a brand new unit too right?

Yep, It was brand new. I should have realised it was the head unit straight away because all Clarion head units have a protective clear plastic on the face to protect from scratches that you can peel off once installed yet mine didn't have that and the transit screws at the top of the unit were missing too...I'm guessing it was faulty and returned previously but got placed back with the good stock by mistake.