Pre-Outs & RCA's

[Chevyaudio 5,000+ posts]

Alright, well in my last thread i was asking if A sub pre out could go bad, well now i know it for sure did, because i hooked up my GF's HU to my truck and the poping bass sound stopped comming from the sub. So now my question is this, is it rare for these things to go out (if it is any help i do turn my sub control down and up alot, because sometimes i just fell like listing to mid-bass). Also i heard that an amp can back feed power into the HU, causing the pre-outs to go bad, is this true? Finally is there any way to test preouts, with a dmm, or other testing device. Any help is appriciated, THanks.

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[Chevyaudio 5,000+ posts]

Anyone?

 

[Chevyaudio 5,000+ posts]

any one know

 

[creater 10+ year member]

i guess you can use a dmm...if the pre outs gone bad i guess it can be replaced...

 

[Slody4Futbol 10+ year member]

calm down lol... you posted 2 hours ago... most people sleep in the mornings... anywayz... what kind of head unit do you have? that 9853? definitely check your amp ground... some radios can just be defective... but a bad ground can cause that... it will try to ground itself through rca's and mess the preouts up on the radio

 

[creater 10+ year member]

i dont know if that amp feeding bad power thing is true...you got me there...but i highly doubt that...because why would a manufacturer make a product that damages other products...although some do do that but not in the audio industry

 

[Chevyaudio 5,000+ posts]

Im sure its not the ground, as I said in my post, i switched HU's and the problem stoped, the main question im asking is if an amplifier, can backfeed power into an HU, because, i dont wanna buy a new HU and have this happen again.

 

[creater 10+ year member]

i've never heard anything about the amp giving bad power as i already said...

and yeah...you should wait a good couple of hours for a reply...or post and come back lil later and check

 

[Slody4Futbol 10+ year member]

how SURE are you that it's not your ground? just because you switched head units an it stopped doesn't mean anything... overtime a loose ground could cause it to ground through the rca's... same way an antenna can ground a radio even if it already has a ground wire... i've seen many radios where when i've unplugged the antenna the radio just shut off... because the other ground was weak... i'd check over your grounds to be sure... but it could be just a defective headunit... i've seen more and more defective out of box headunits these days...

 

[Chevyaudio 5,000+ posts]

yeah, i know i was a little anxious, i was up all night messing with it ,sry, ill check back tomorrow.

 

[Chevyaudio 5,000+ posts]

im pretty sure, but ill run a new ground lateron tonite, would it be best to run it all the way to the negative battery terminal or to a piece of metal behind the dash.

 

[Slody4Futbol 10+ year member]

ground the head unit to a clean piece of metal behind the dash... or run a wire to the battery... i did both... and get all the paint off the chassis that you ground the amp to... sand it down clean... then screw the ground in with a ring terminal and washer... make sure you can't twist the ground wire or move it at all

 

[maylar 10+ year member]

An amp cannot "feed back" to the preout unless the amp is severely broken. It is possible to damage a preout driver in a HU by shorting the RCA however.

As for the problem going away with a different HU, are they EXACTLY the same models? The symptoms you mention are similar to overdriving the amp, and different HU's have different preout voltages which might make you come to the wrong conclusion.

Did you try turning the amp gain down first?

 

[Chevyaudio 5,000+ posts]

well another day another post. I went ahead and ran a new ground last night just to be sure that, that wasnt the problem, but somehow before i could test it the sub preout is completely gone now(dont know how, being that the amp hasnt been hooked up in a week), so it must of been a defective unit, or while i was installing my midrange ampa week ago i may accedently shorted the Sub RCA's together. Maylar, my gains are set corectly i used a dmm when i hooked everything up, so i guess its off to the classifieds to look for a new CD player.

Thanks for all the help guys.

 

[Chevyaudio 5,000+ posts]

one more question, Maylar made the comment that it sounds like im overdriving the amp. Are you saying that the symptoms i described (poping bass sound from the subs, when HU is powered on/off, and CD being ejected and inserted) or that a Pre-Out going bad is a sign of the amp being overdriven?