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Discussion Starter #1
I have a set of Alpine SPX-17PRO (100 rms 4-ohm) powered by a JL Slash 450/4 and an Alpine CDA-7998R. I was told this deck does not clip at max volume (35). I don't have an o-scope right now to confirm that, but I am going to trust that statement. I set the gain with the deck on max volume to 20 volts. I have 4 conductor wire running to each door and have the Alpine crossovers in the rear. I have the crossovers configured with the 4 and 3 module and -3db and 0db tweeter jumpers (Type C). I am not running a sub or rear speakers right now. These speakers sound horrible and keep distorting around 28. They are not loud at all either. My stock speakers sounded so much better then they do. I cannot figure out what the problem is. This is my first time amplifying components and it's just been a disaster. I hope I am just overlooking something stupid. If you need any more information, just ask.

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Maybe you're better off setting up your amp at 27 volume instead of 35 'til you confirm that the deck doesn't distort at max volume and see how that goes.
 

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Do you have a high pass crossover applied?
 

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Discussion Starter #5
I had the HP on the amp. What should I set the slope, Freq. Range and Filter Freq. to? I am pretty lost at this point. If I don't get it soon, I am going to take it to the professionals. Also, what is considers a high input and a low input for the preouts?
 

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Were you using this alpine head unit for your stock speakers aswell?
 

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Try starting over.

-Set the crossover on the speakers to 80hz/24db (the Pro's are great speakers, but deep bass isn't a strong point).

-Turn the gain all the way down. DON'T set it using the voltage method.

-Turn the HU volume to 27/35

-Play some pop music on CD (something like Britney Spears ;))

-Sit in the seat and have somebody slowly increase the gain until you hear it begin to distort (or it's too loud to be enjoyed) and turn it back down slightly (you can do this running back and forth too)

You have now set your max unclipped volume. You use pop music because it's usually poorly recorded and heavily compressed. You use 27/35 because well recorded music (with good dynamics) will sound quiet at 27, so you have some room to safely increase the output on those tracks by going up (I still wouldn't go over around 31-32 just to make certain the HU doesn't clip the signal).

NOTE: If you still have problems...I would bet it's install related. If you don't have any bass, you need to seal the holes in the doors, build a better baffle, or do both. If you try and get bass by turning up the "bass", you are very likely to clip the signal again and it will sound like poo (or kill your speakers).
 

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Discussion Starter #10
I am going to give that a try. I will post back when I am finished. Also, the radio also has a crossover in it. Should I set that identical to the amp? If not, what should I set it to?
 

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Try just starting with the amp. Leave the HU alone for now.
 

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Might want to turn off/disable any sound enhancers like SLA (sound level adjustment) and loudness and set your EQ to "Flat" before doing the process...
 

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Discussion Starter #13
I set the crossover and it still sounds like cramp. You don't even have to turn it up loud for it to distort. The eq is flat. The head unit has media xpander. I don't know what it is. I have that off. Also, should I have the defeat on or off? Either way with the defeat or xpander on or off I can't hear a difference. Do think it could be the head unit? I tried a different JL amp I had and it did the same thing. (JL 500/5).
 

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May be the head unit, but don't come to conclusions just yet. What if you use the "rear" pre outs on the head unit and see if they still distort.
 

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Discussion Starter #15
I just tried using the rear RCAs and it didn't work. I also reset the head unit to factory settings and still nothing.
 

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Stupid question time..... have you checked the speaker resistance to see if they are blown? I think mine read 3.5 ohms or so on the midbass last time I took pics of them to sell.
 

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Check to be sure that the tweeter is connected to the tweeter output and the woofer is connected to the woofer output. This would cause the speaker to sound terrible and distort easily.
 

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Discussion Starter #19
I am positive the speakers are hooked up correct. Everything is inphase. I checked over them so many times. Even called alpine to verify tweeter polarity.
 

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Discussion Starter #20
I tested the speakers without taking them off the crossover. Can you do that? Anyways. All the speakers are 3.1-3.2ohms. I know they are 4ohm speakers. Is that okay?
 
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