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I supported Toymods
Location: Frankston, Victoria
Registered: April 2004
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Amplifier Problem, crackling sound through speakers...
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Wed, 17 November 2004 11:09
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Hey people,
This is very long as I try to explain everything, but bear with me 
OK I bought a second hand amp the other day. It's a Sound Barrier 4x100W amp, (I know, home brand, no frills, hehe ). Anyway I heard it in the dude's car it was in before and it sounded perfect.
So I hooked it up in my car the other day and bridged 2 channels to run my 15" 250WRMS Subby and bridged the other 2 channels to run some 300WPMPO 6x9s (my rear right speaker wire must be loose somewhere so im using just the left to run both 6x9s).
All was going smoothly for about 10 minutes and it sounded fooly sik. Then all hell broke loose and i had a very high pitched crackling sound coming through the 6x9s. I quickly turned everything off in my panic.
So I've tryed a few things to fix it, nothing seems to work. I think it is coming through the subby too, just too high pitched to be able to hear it properly. I also tryed hooking up my old 6" speakers to where the 6x9s were plugged in, same thing.
I've been told by a friend that I may have a wiring problem, as when the volume is up very high the lights slightly dim. But then today something freaked me out completely. I had it running for about 15 minutes listening to some very bassy music at fairly high volume, the crackles came thru every now and then, but I beared with it, then mum came out and told me to turn the shit down or the neighbours will complain (9:30PM...). So I turn it down to the lowest volume possible and explain to her that I'm testing the amp again, then I look down and all of a sudden the lights inside my car flicker, then turn off, on, off, on, off, then on, then flicker, then i quickly bent down to turn ACC off.
So at this stage I'm thinking, FUCK my battery must be flat. I turn the key to ignition and the dash lights turn on and I'm thinking, hmmm seems I must have a bit of power. I turn the key and it starts instantly, as good as ever..... I'm thinking the amp must have drained all the accessories and lights of power, but still left the battery almost untouched.
Anyway the amp has been unhooked now because I'm too freaked out to touch it again... Any help??
Thanks,
Kev.
EDIT: I changed the title.
[Updated on: Wed, 17 November 2004 11:28]
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Location: Perth Australia
Registered: November 2004
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Re: Amplifier Problem, crackling sound through speakers...
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Wed, 17 November 2004 13:42

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im not too sure, but check the wiring to the amp like powerwise, it could be an earth problem or power problem, though i figured if it was an earthing problem the amp wouldnt turn on. how is the amp hooked up to the head unit? i am guessing you used RCA pre outs from the headunit to the RCA input to the amp, check and make sure there are no shorts or anything, hmm it could also be that you are trying to pull too much power through the amp into the speakers, you said you are bridging two channels and running 2 6x9's off the left channel? im not too certain what you mean by that though =\ if its like two speakers hooked up parallel the amp would be running 2 ohm instead of its usual 4 (most run at 4 so im guessing) just check all the wiring i guess. =\ or just sell the amp and buy another one
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Location: Gawler, SA
Registered: August 2003
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Re: Amplifier Problem, crackling sound through speakers...
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Wed, 17 November 2004 14:01

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I got told by someone that you cant bridge two channels and run seperate speakers off the others like that. They said it produced 'interference' in the non-bridged channels. Havent tried it so Im not sure if theres any truth to it.
Could also be the 2-ohm thing..
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Location: Castle Hill
Registered: December 2002
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Re: Amplifier Problem, crackling sound through speakers...
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Wed, 17 November 2004 15:01

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Hey like all these guys said check earths, wiring, the 2 ohm thing etc. could be a lot of diff things.
My main concern would be - is the amp set up to be bridged? My 4 channel amp has a switch to run in 4,3 or 2 channel mode. From my understanding you should not bridge channels that aren't meant to be bridged - especially on head units, which on the new ones can fry them? not sure. anyway. Also is the amp capable of running 2 ohm stable? Because depending on the way you set up the wiring (check some websites to make sure) you can be presenting a 2 ohm, 4 or 8 ohm load onto the amp. If the amp is only meant to run at 4 ohm, you might be in trouble...
Ok, I'll stop blabbing but just sum up with this:
Cheap amp, recommended (good doof for dollar) from myself and mate, would suit the speakers you talked about nice in 3 channel mode....
Fly 800w Max 4 channel $200 SuperCheap special!
And check websites re: what you can and can't bridge, how to do wiring, and see if you can find out what your Sound Barrier 4x100W amp is capable of i.e. 2 ohm stable etc is it RMS or Max?
PS something dodgy going on if "lights inside my car flicker, then turn off, on, off, on, off, then on, then flicker"
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Location: Albion Park, NSW
Registered: October 2004
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Re: Amplifier Problem, crackling sound through speakers...
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Thu, 18 November 2004 06:57

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So many possibilities as others have mentioned.
Trying to work out how you've set it up from what you've said. It sounds like you're using the left rear speaker output from your head unit as the source signal for the amp? And that the rear right speaker output isn't working for some reason? This indicates there is a problem with either the head unit or the wiring for the rear right speaker. Perhaps the problem with the right speaker is that it's shorting out somewhere on the car body and causing earth problems for the whole car. Or maybe whatever is wrong Considering you know there's a problem there I'd start with that first before even hooking up the amp. Make sure it can all work of the head unit, then plug the amp back in.
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I supported Toymods
Location: Frankston, Victoria
Registered: April 2004
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Re: Amplifier Problem, crackling sound through speakers...
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Thu, 18 November 2004 08:22

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!!! Reading that, I just realized!
OK I rewired the power for the amp today and it still crackles, but I noticed something weird. I had the acc on and was playing music with just my front 2 speakers., the amp pos wire was not connected to the battery at this time. I had it all ready and thought it would be best to plug the ground wire into the amp before hooking the pos wire up on both ends. And there it was, as soon as I put the ground wire in, the headunit dropped to extremely low volume and 30 volume was like it was on 1. So I pulled the ground wire back out of the amp and did it again, same thing. Then I unplugged the rear speaker input from the amp and did it again, and nothing happened to the headunit! I'm thinking the one wire from the ok speaker wire must be bared somewhere and is probably touching the body somewhere, and when I plugged the ground in, it grounded both of them, meaning they connected together, meaning they shorted and sent feedback straight towards the headunit, hence the volume on the headunit dying...
Anyway that was a long rambling speech and I cant be fkd reading it over again. I will unwire the rear speaker wires, check the cabling and rewire them down the other side of the car (as to remove the alternator whine from the battery wire too)... Once it stops raining... bloody melbourne weather...
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I supported Toymods
Location: Frankston, Victoria
Registered: April 2004
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Re: Amplifier Problem, crackling sound through speakers...
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Fri, 19 November 2004 09:03
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Ey peeps, thanks for all your help. After totally rewiring the battery & speakers, trying different speakers, trying a different subby and a whole bunch of other things, I realized that the back panel on the amp where the input plugs in... was loose, basically the panel was slightly falling into the amp because a screw was missing, and due to this, it was crossing the connectors, hence crackling.... It's all good now and u can read it all and check out some new pics on the link to My Car in my signature.
Thanks again,
Kev.
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