Austarion

ive wired up an amp and subwoofer to my cd player.. its a "coustic" amplifier.

what i would like to know is why everytime i drive and am reving up the gears, it makes this noise.. kinda like a jet noise.. it didnt use to happen with the alpine amp i previously had..

ive wired up the positive power cable down the drivers side, and the audio cables down the passengers side..

Some reading for you
http://www.nzicemag.co.nz/index.php?p=articles&id=18

Its quite common. Id say make sure you got a really good earth to the chassis. You may also find that the Alpine amp had a better power 'filter' in it (cant think of the right word).

"When the alternator is driven to its maximum power, damage can be caused that can result in a tiny amount of AC voltage entering into your system."

how likely is it that this has happened to my car.. the amp is only 480 watts..

also if the amp is in the boot.. where is a good ground to ground it? currently it is grounded to the black metal of the boot.. i suspect that is the problem.. might have to sand off some of that black paint as it didnt seem like a good idea anyway..

As far as I can remember, Coustic is a reputable brand so it shouldn't do that - most alternator whine is caused by shitty power filtering on cheap audio components or bad cabling.

Do you have any areas where you have signal wires running along side power wires (ie. do you have the RCA cable and the power wire for the amp running together)? Good source of noise if you do. Separate them as much as possible - if they have to cross, make sure they cross at 90 degrees.

hcca wrote:Do you have any areas where you have signal wires running along side power wires (ie. do you have the RCA cable and the power wire for the amp running together)? Good source of noise if you do. Separate them as much as possible - if they have to cross, make sure they cross at 90 degrees.

rca - lhs of the car
power - rhs of the car

the only thing i can think of is bad ground.. im hoping its not my alternator.. :(

If all else fails you can buy a noise suppression filter which you can put in the permanent active wire to your amp.

wheres the amp mounted is it srewed on a metal surface that can cause ground loops so the amp is getting two grounds and they have a voltage difference in them maybe just 0,1 - 0,3 can enough to make thi whine

My stereo with amp has the wires RCA and Power runs down left hand side spaced apart by about 6inches? under the back seat they both loop from side to side. It made no noise like a high pitch wine.

Once the PS2 went in the Auxillary output made this noise and only does it when the PS2 on. It may be the transformer thing has gone too close to the amp or the RCA's.

I tried the suppression filter thing but it still makes a noise. Yes there is a decent improvement. Installed between the amp and RCA lead that goes to amp.

If this is placed between PS2 and Head unit would that make a difference?
Will try it out when have a moment or two.

i had some thing in my car it was quite cool when i had it tuned into a low frequency station, i would rev the engine it would make a sound through the speakers like an 80's nintendo moto GP game i dont think it does it any more but it was cool when it did


bigmoz :pimp

A big source of unwanted noise is usually picked up accross the RCA from the deck to the amp.
This is because the peak to peak signal at this point is low therefore noise can easily add itself to it and become amplified.
A long piece of RCA cable can act as an antenna and pick up small stray noise before amplification hence thay become large noise at the amplifiers output, you can help reduce noise by using the shortest possible RCA leads and make sure they are shielded.
Also dont coil excess lead rather bunch it together in layers this will help reduce unwanted inductance.
Many filters are capacitive and are designed to block DC signals, most noise is AC so will be ineffective.

AC noise can also find its way into the supply of power into the amplifier this is one reason why capacitors are used accross power supplies.

Well at least ive learned something at TAFE

if i mounted my amp in the boot.. where would you guys remommend i ground it? somewhere thats bare metal inpainted..

androoz wrote:if i mounted my amp in the boot.. where would you guys remommend i ground it? somewhere thats bare metal inpainted..

What I do is mount it where-ever is convinent. To ground it Id get a ring terminal for the earth lead. Remove a bolt in the boot, and put that bolt back in with the ring around it.

Has worked for me every audio install so far.

You should get the same voltage across your battery terminals, as you do in the boot. If thats not the case, then replacing the earth line off the battery might be a good idea.

Also try another amp. It could be as simple as you have a bad amp. Personally I have never had any signal noise problems in any of the cars Ive worked on (5 of my own installs). Quality RCA leads, quality power lines, hooked on opposite sides of the car (Starion I ran the RCA down the centre tho). Been sweet as. I also run a new power line direct from the battery (via fuse) for the headunit to make sure it gets a happy signal feed too.

I think its your amp. See if you can borrow another to see if its a problem that started when you installed the amp, or if the amp itself is faulty.

SpidersWeb wrote:What I do is mount it where-ever is convinent. To ground it Id get a ring terminal for the earth lead. Remove a bolt in the boot, and put that bolt back in with the ring around it.

Same here never a problem, if ur worried about the paint stopping the earth, just get a bit of sand paper and scratch the little area around the bolt :)