Can a pre-amp/equalizer cause noise?

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=41952
Printed Date: May 17, 2024 at 3:13 PM

Topic: Can a pre-amp/equalizer cause noise?

Posted By: keymaster
Subject: Can a pre-amp/equalizer cause noise?
Date Posted: October 30, 2004 at 10:07 PM

I thought the new Alpine deck I bought today would make the whining in my speakers go away, but it's still there. The guy at Circuit City said that the Kenwood pre-amp/equalizer that I have feeding my two amps is probably causing some of that noise. Anyone found that to be true?

The Alpine that I bought has 3 RCA outputs, so I don't REALLY need it like I used to. There is one SUB output and two other outputs for my amps that will run my door speakers. Would it be best to just use those and take the pre-amp out. I like to play with my sound a little here and there, but if it is causing this whining noise, I'll take it out.

BTW, vehicle is a 1997 F-150

Thanks

-------------
1997 F-150 4.6L Auto Regular Cab
Alpine Mp3 H/U
Kenwood Preamp
Rockford Fosgate Punch 60
2 12" Rockford Fosgate Audiophiles
Small 2-way amp for rear speakers
Custom enclosure for subs made by me

Replies:

Posted By: Poormanq45
Date Posted: October 30, 2004 at 10:23 PM

Well, to answer your question, yes it is possible for a pre-amp/equalizer to cause noise in your system. But I don't think that is your problem.

You have changed decks and the problem persists. So it's not the HU. That leaves the pre-amp/equalizer and the speakers.

Can you verify that the pre-amp/equalizer is properly grounded. Either to the frame(bare metal) or the negative battery terminal. That's what usually causes a "whining" sound in stereo systems.

Another less likely possibility is that something may be wrong with one or more of your speakers. I had a pair of speakers that "whined" after they "blew". Replacing them fixed the problem.

-------------

Posted By: jeffchilcott
Date Posted: October 30, 2004 at 10:40 PM

We have had problems with a few in dash eq's causing noise...I try to tap a seprate power source then the radio's and ground to a spot as close as possible to the eq..Also the rca's you run can make a huge diffrence when running through that short area of dash there are alot of live wires, ac, heat all though's try moving some wires around and see if the problem gets better or worse

-------------
2009 0-1000 Trunk WR 154.0DB 2009 1001+ Trunk WR
2007 USACI World Champion
2007 World Record
2006 USACI Finals 2nd Place

Posted By: Rushman
Date Posted: October 30, 2004 at 11:22 PM

I just want to vouch for the RCAs making a huge difference. Installed a system in my 99 F-150 with an ///Alpine pre-amp and got a little whine with that too. Changed out all the RCAs with shielded Schoche cables and routed them away from the amps power wire and no more whine.

-------------
99 F-one fitty
Pioneer Premier H/U
Alpine EQ
Kicker 1200 amp
4 Kicker comp 10s
6 kicker SS65.2 components

Posted By: kenmci
Date Posted: October 31, 2004 at 12:54 AM

usually you will pick up whine when there is either a grounding problem, or when your RCAs are too close to power wire or stock wiring for that matter. Like everyone said RCAs do make a difference. A quick check is to take a set of RCAs and run them right down the middle of the car from you Eq to your amps and see if the whine goes away, if it does then try rerouting your RCAs.

Posted By: audiopro111
Date Posted: October 31, 2004 at 1:37 AM

yeah rca's will definitly make a diffrence but what it almost a guarantee is your power source i would get power from a diffrent source as the radio as jeffchilcott says and last but not least make sure u have a good GROUND......

-------------
AudioPro111

Posted By: offroadbum
Date Posted: October 31, 2004 at 4:58 PM

Kenwood eq`s are real bad about this.You can soilder you ground to the HU.If that doesn`t help,open it up and look for loose soilder joints in the ground circuit which is most likely with kenwood.

Posted By: keymaster
Date Posted: October 31, 2004 at 8:41 PM

Thanks for all the great replies. I will admit, I was anxious when installing the amps and I did run the RCA's and power wires together. I will definately fix that.

The preamp is grounded to the ground wire in the factory harness. Should it be grounded to the chassis instead?

Thanks again

Posted By: jeffchilcott
Date Posted: October 31, 2004 at 8:53 PM

i would probably ground it to the chasis as close to the eq as possible I know in most cars you alright, but in my SQ car I dont even use the factory ground for the head unit I use a chassis ground

-------------
2009 0-1000 Trunk WR 154.0DB 2009 1001+ Trunk WR
2007 USACI World Champion
2007 World Record
2006 USACI Finals 2nd Place