Help: Very loud amp feedback noise!

[NJ_Steve]

I've done my searching and can't make sense of this problem.

Background info: I have a Kicker 850.4 grounded and powered directly off my battery (relocated to the rear of the car) with 5' 2awg cables. The amp is feeding MB Quart components off of channels 1&2 and Subs off of channels 3&4. I have a JVC KDR01 H/U (also powered and grounded directly from the same battery) feeding the amp. Not sure if it matters, but the car is a '93 RX-7 w/ a LS-1 conversion. Channels 3&4 seem to operate fine, the subs get nice and loud with good sq.

Here is the problem: If I turn the amp gain (dial on the top of the amp) anywhere above 0, I get this instant and incredibly loud feedback sound coming through my MB Quarts speakers. I've only done this three times now and each time I quickly turn the system off to keep from blowing my speakers (yes, it's that loud). The first time this happend, the JVC was feeding the amp with RCAs routed near the speaker lines and I thought there may have been some coupling between them. So, I move the RCAs away from all wires by routing them down the center of the car and the problem was still there. So next I remove the RCAs from the amp all together and loop the Ch 1&2 inputs to eachother (attempting to short the input) and the problem is still there.

Basically, all I have now is an amp with no input powering speakers. The battery voltage is fine (~12.3V).

Is my amp bad? It's brand new from onlinecarstereo.com and claims to have been tested at the factory so I'd be suprised.

Please help!

Thanks In Advance for any help,

Steve

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[NJ_Steve]

After some more digging, I'm pretty sure I found the problem. I'm posting it here for the next guy to search for something like this because I've gotten very frusterated finding similar problems posted, but few people every post the solution after they've fixed it.... //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif ... anyway ...

It looks like one of my speakers was wired poorly and one of the lines was inadvertently tied to a ground point. This sent the Kicker amp into a strange cyclic output protection mode which oscilated at a fairly high rate (~750 Hz) and REALLY LOUD. Once I pulled that speaker off the amp the problem went away... //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[tez4life Premium Member]

Glad you solved the problem you were having. I bout a Rockford Fosgate amp off Ebay back in 01 or 02 and it had a very similar problem with feedback noise. I was so pissed because it was suppose to be brand new that I just sold it to one of my friends for little to nothing..

BTW, '93 RX-7 w/ a LS-1 conversion must be a very fun car to drive //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[NJ_Steve]

BTW, '93 RX-7 w/ a LS-1 conversion must be a very fun car to drive //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

Fun to drive - Yes, fun like when I was 6 and my parents let me watch "Nightmare on Elm St." for the first time.... //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[dB-r 10+ year member]

Yeah, that would be a cool coversion to do. power to weight ratio is OMG on that conversion... LOL

Kicker amps and lots of other amps that are designed fairly well are sensitve to things like grounded out speakers.