audio g man

Is the amp power wire far enough away from the rca leads? Ideally the power cable should go down one side of the car and the rca's down the other side or next to the transmission tunnel.

The amp power cable needs to be kept away from the HT leads.

It's good practice to earth all amps to one point to avoid a ground loop. Keep earth wires fairly short and make sure the earth terminal is screwed down to clean bare metal with a good chunky screw. The earth cable should be the same size as the power cable or bigger.

Might be worth fitting a new earth wire from the battery to the chassis and also from the alternator to the chassis.



[Edited by audio g man - 8/7/2002 11:59:25 PM]

UHF

I just had a 4 channel amp installed with dual mags in the front and kappas in the back but i'm getting a horrible whine which gets higher pitched with the revs, I'm assuming its the alternator.

Whats weird is that its only affecting the rears despite all 4 running from the same amp!

Any suggestions? also does anyone know how meaty the standard alternator is in the MY99, i was thinking of using a power cap but if the alternator is good I wont have to (for the subs that is)

Cheers

chiark

The alternator should be good for around 100A-ish I reckon. Don't know this for fact, but empirical evidence seems to suggest so.

Whine on the back speakers? Are you running separate RCAs to the back speakers? If so, swap front to back and see if the problem moves, then take it from there...

Big Goon

Try this m8ty, I have similar problem, gonna try to sort 2morrow.

http://www.termpro.com/articles/noise.html

HHxx

IIRC, I don't think the standard alternator is quite 100 amp one. More like 65/75. Most diesels have around 90 amp alternators.

H

chiark

Cheers H, I'll add that to the "pool of knowledge". That's a bit wimpy really - my Clio had an 80A alternator.

UHF

I sent you a mail Chiark, those installers are muppets

chiark

UHF - not received it yet. What had they done???

UHF

really, I sent it to hotmail account last night.

They put in shoe lace style power cable and the door cables got trapped in the window mechanism and pulled off the back of the speaker and bent the terminals, they then grounded, flattened the battery and left me stranded in Hounslow! which is bigger, 8 gauge or 4 gauge, cos they put one of those in my fiesta and put the smaller one in my subaru even though the subaru has more amps in it!! daft!

chiark

hotmail's strange. 29 useless emails there - nothing relevant

Shoelace style power cable? That'll cause your amp turning off . In my stupidity of installing my first amp I used chunky power cable but yes, I neglected the earth. It turned off at regular intervals. Current is the same throughout a circuit - d'oh. In my defense, I was young...

So, other than using crap cable and installing the speaker cable in the wrong place so as to damage your speakers when you close the window, you're happy with them?

Glad you've got it sorted. If you pay someone, you don't expect this sort of hassle!!!

chiark

...and, for reference, 4AWG is bigger than 8AWG. The smaller the number, the thicker the cable. I would guess that you should be running 4AWG into a distribution block if you're hanging two amps off there. 8AWG from block to amp should be fine as you're not running silly amps

UHF

It isnt sorted, going back there this afternoon, I phoned just now and they said that the power cable was more than adequate but I'll get them to run a chunky peice temporarily on the floor and show them how the amps dont cut out once they've done it

UHF

RA5004 and Hifonics Son of Boltars should have bigger cables tho?

chiark

Son of Boltar - 150Wx2, protected by a 60A fuse. Assume that your cable must be able to handle over 60A then. The IASCA table suggests that for 0-7 feet you need 8AWG cable to handle 65A.

infinity RA5004 4x50 or 2x300W. Should be around an 60A fuse again as I reckon those figures are overstated, but it may be 80A. For 0-7 feet of run, 6AWG is suggested for up to 85A, which is hard to get hold of. 8 should be acceptable, 4 is better. Check the rating of the fuse to see if you're likely to draw 80A though, as I doubt you'll need it.

I'm guessing that you're using a single fused cable from the battery to a distribution block. Your master fuse should be around 100A MAX (mine's 80 and has never blown with a Soundstream 604 and Rockford Punch 200ix).

For 100A, you're looking at 10 feet maximum run for 4AWG, or 2AWG for more. This is damned expensive though.

For reference, see the RAC FAQ / electrical section 2.3

Whatever, your system should not be powered by 8 AWG.

Your earth cable needs to be chunky too!!!!!

UHF

The main fuse is a oversize standard car fuse style thing, with a 60A fuse in it and since i'm running the son of boltar into a pair of subs its running bridged parralel mode at 2Ohm's so its closer to 500wx1 which means its probably running very high, it gets damn hot.

But looks like my 8gauge is totally inadequate, but the shop disagrees, how do I convince them? they put 4gauge and a nice gold plated vacumn fuse style holder in my fiesta when I had less amps! I think they just dont want to rip the car apart again. advice, what can I say to convince them?

chiark

Use the IASCA table linked above.

If 8AWG tries to flow 60A, which it will do before the fuse blows, you will get considerable voltage drop over the cable because the cable will be heating up. This is unsafe for fairly obvious reasons!

The voltage drop is what is causing your infinity amp to turn off would be my guess. You can confirm this by putting a voltmeter across the amps terminals and seeing how low it gets when the bass starts moving. Or just disconnect the RCAs from the boltar and check that the infinity works no matter how loud you play. If it does, the Hifonics is drawing too much power and the supply line is sagging too much. This is likely down to the thickness of the wire.

Also, check that your earth point can flow 60A, and that the earth cable is the same size as the power cable.

I assume they've put a good grommet around the cable going through the firewall and that the fuse is within 18" of the battery...

So, to convince them, disconnect the RCAs from the boltar, play a piece of music at a volume level that you KNOW shuts down the amp, show 'em it works, connect up the boltar, show 'em it shutting off.

UHF

they have already started saying that the battery went flat because the alternator isnt putting out enough power, they will try to send me to subaru and say it aint theier fault but I do know if I turn the subs off from the head unit (has sub control) then the system runs fine, turn the subs on and the 4 channels die again, i'll measure the voltage at the end of the cable and see.

chiark

Yep, that'll convince 'em. Measure the voltage across the battery terminals, then the voltage across the amplifier terminals.

It always *could* be your alternator, but I find that unlikely.

UHF

well there is an alternator whine, but everything else aside the amps are rated too high for the cable arent they!

chiark

You may want to print out the "electrical" page of the RAC FAQ as that's got an alternator whine troubleshooting "howto".

Sheesh, these guys are professionals??????

UHF

naming and shaming this evening if they dont sort it out!

chiark

I think Scoobynet doesn't have any issues with you doing that from what you have said.

You may want to point out that Scoobynet has 15000 members and has an active ICE forum, too. Please do NOT use that as a threat, but it may interest them to know that people are watching your plight.

Nick
(ICE moderator)

UHF

no i wont use it as a threat, but I will let you guys know for reference so you dont get stung at the same place, i wont use scoobynet for my own personal gain to sway the shops decision, thats immoral

audio g man

Whats the outcome?

UHF

oh sorry, well they replaced the door wires they screwed up (red faces all round), anyway they still reckon that the power cables were thick enough and that the alternator whine they could only supress at amp end, which I dont want because it should be suppressed at the source, namely the alternator.

The cutting out was due to a dead battery, 3 out of the 8 cells were fried, got new battery now, nothing cuts out but alternator whine still there! help!

David_Wallis

to be honest, if they can supress the noise then who gives a **** how they do it, be it a ceramic cap across the alternator or the amp... either way if they remove a ground loop or the noise... job done...

Not that im defending them but I hate alternator whine...

I didnt pay over £1000 for a headunit (Nakamichi MB100) for a whine...

David

UHF

jesus, why so much on a headunit, what does it do that a £500 one doesnt?

David_Wallis

Single din, 6 disks in the dashboard.. (No changer required) No speaker outputs... Just digital output with 24bit external D/A Converter. Was one of if not the first RDS units in the country, as Magazines were reviewing non rds models...

Dont even get switchable illumination... you order with the colour you want.

David

UHF

kewl, digital output sounds like fun where the hell does it store 6 cd's tho!! suppose theres no point me having internal amps either, a bit pointless if your running external amps, just takes up more room!

David_Wallis

probably stores them where the amp would normally be.. (D/A convertor is external..)

http://www.nakamichi.com/auto/musicbank/MB100.HTML

David