Hello, Recently I put a pir of tweeters on my car. My HU have 4 channels, to front and two rear...so I connect the tweeter on the front on per channel because I dont have the 3.5 already installed..but I see that they dont sound clear..the make a noise...I need to put to a crossover to make it work right?
the location of the tweeter will affect the sound?
in this photo you can see were I put it

Move your tweeters, they are in one of the worst possible spots, sorry to say. The sound out of a tweeter is highly directional. The left tweeter is very close to your head while the passenger tweeter is much further away. This car looks like an older Cavalier or Sunbird, is that correct? If you must have those tweeters and want them visible like that, mount them way down near the dash on the same panel, that will help to equalize the pathlengths.
Yes you need a crossover for the tweeters, do not continue to play them without crossovers or you'll be buying new tweeters like right now. If you are going to be putting in 3.5" speakers in the factory location, consider buying one good pair of 3.5" speakers like the MB Quart DKE108 and you will not even need those extra tweeters and crossovers.
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Top Secret, I can tell you but then my wife will kill me.
"consider buying one good pair of 3.5" speakers like the MB Quart DKE108 and you will not even need those extra tweeters and crossovers"
Agreed, MB Quart speakers are quite possibly the best thing on the market. They're pricy but they will make odd installs like that of your tweeters a thing of the past.
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OK, thanks for your help...You say that I need to put like in this photo?

That would be a good start if you plan on keeping them and adding 3.5" speakers. Still not ideal but waaaaaaaay better than the first picture. Buy the 3.5" MB Quarts, it will solve all problems.
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Top Secret, I can tell you but then my wife will kill me.
I had Alpine Type R components and when I mounted the tweeters I sat like I would when I was driving, then figured out where my ear level was and marked it on the A pillar of each side. That way I was getting the sound from the tweeters at exactly my ear level and they sounded great. Good luck.