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Posted

Today I had installed 4 Polk DB651s in each door and this little Alpine amp:

http://www.crutchfield.com/p_500KTP445U/Alpine-KTP-445U-Power-Pack.html?search=ktp445u&skipvs=T

 

Still running factory head unit and want to keep it that way.

The music sounds just excellent! Except......there is now an audible HISS at low volumes and when changing XM stations. I can almost live with this hiss, but the turn signal and backup sensor are deafening! I had a local shop do the install. They said there is nothing that can be done about all of this because of this particular amp. I've read several threads about these problems, but those were with different amps, not this particular power pack version. Also, the installer said he adjusted down the gain as much as possible to try and fix the hiss.

 

So.....what can I do? Is there anything that can be done without spending and arm and a leg? Should I just remove the amp and live with the Polks running off the factory head unit? The amp fit behind the dash, so I can't get to it easily.

 

I pick out all my equipment, but I let the shop do the installs. So dumb it down a little for me.

 

Thanks for your help.

Posted

Ive dealt with a hiss like that before when i have a bad ground for the amp. Also if you have your cables running near gas pedal. drive by wire affects it.

 

And you dont want the polks running solo off stock HU! It will sound like crap. been there down that..

 

Have you thought about changing HU?

Posted

I would really prefer to stick with the stock HU for now. No cables near gas pedal.

 

If I could even cut the hiss & signal/chimes volume level in half, I would be fine.

 

Forgot to mention I've got non-Bose setup.

Posted

Are your RCA cables running next to your power cable? I don't think it has anything to do with that amp, it is an install issue.

 

Since you are using the stock radio, they had to use a line input converter to change the low voltage speaker output to RCA, it may have something to do with that module and its location.

 

As stated earlier you can check the ground, and move it to another location.

Posted

The only thing that will help is to turn down the gains on the amplifier. All the way down if necessary.

 

It will lower the music volume, the turn signal/chime volume and the hiss.

 

Surprised that your installer didn't do this when they did the install...

Posted

i'm going to tell you right now. i'm not surprised. I work very closely with a few local audio shops. they have NEVER EVER EVER had good luck with those hunks of junk. i would see if you can return it to get your money back and step up to a real amplifier. they've had several dead on arrival. several with alternator whine that will not go away no matter what. several that have a raspy sound. alpine dropped the ball big time on that thing. it was designed to be an easy add on amp that you can put anywhere and was originally said to "be the size of a candy bar" as you can see that is one hell of a candy bar.... i would honestly cut your losses stop giving yourself a headache and get rid of it you'll be much happier.

 

 

and please don't think i just hate on alpine, i love alpine i've always ran their speakers decks and amps in all my vehicles. currently have 2 tens and amp in my truck, and an alpine deck in my jeep. this particular amp you picked is just junk

Posted

Thanks for all the responses.

 

I read LOTS of reviews on Crutchfield, Best Buy, etc. about this Alpine unit and all were glowing and said nothing about the white noise problem. I did my research as best I could to try and avoid problems. But oh we'll.

 

Walt, I'm surprised as well the first shop didn't try lowering the gains all the way before sealing the dang thing back up behind the dash. They were less than helpful and not very willing to look at it again, so I'm not going to mess with them (ever).

 

Went by another shop today (Alpine dealer) who has installed a couple of these before, and they have had the same issue. They think they can fix and really want to so that they know what to do in the future with these units to correct the issues. I was really impressed with them and it will be cheap. They are going to talk about it in the morning and let me know back then what the exact plan will be. I think it involves a new RCA input harness, noise filters, etc. but when I get the specifics ill post them so everybody knows. I told them its got to be cheap or I'm going to cut my losses and pull the thing out (as ruggedlife suggested). But they impressed me enough and assured me it would be a cheap fix, so I probably will let them try.

 

Hopefully I'll have the specifics tomorrow and can get all your opinions. Too bad about this unit. It's great to be able to hide it behind the dash.

 

Posted

Quick update on my Alpine KTP-445u:

 

The 2nd shop I went to installed two PAC ADJ line out converters and still used the filters that came with the amp. This made the HU connection RCA. It was previously speaker level input. The RCA input made all the difference. All white noise (hiss) is gone(or at least that I can hear). The sound is amazing! Just exactly what I expected from some good Polk speakers with a little added power. A full, rich, and clear sound that I wanted.

 

The shop also lowered the gain a good bit, and that drastically helped the turn signal volume and chimes. I'm sure that also helped the hiss some, too. Turn signals are just slightly louder than normal, but not much.

 

I would definitely suggest this little amp that hides behind the dash. But definitely make sure you go the RCA input route if you do get it. At least with the factory GM HU. I know there are much better, more powerful, etc. amps out there. But this one was just right for me. Just took me finding a good, knowledgable installer and a few extra bucks to get there. But hopefully this helps someone else not have to go through that.

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