Supression

[andy 0]

Hi, Have fitted new speakers in a new back shelf with an amp and I'm getting loads of interference (enigine noise breaking through), don't have any problem with just the stereo normally, just with the amp on. Have checked all earths but don't know where to go from here.

Ideas?

Cheers

[dubloke 4]

where have u earthed the amp to? in the boot, ie the shortest run poss is the best way, and must be to bare metal surface not painted! must also be the same thickness or thicker than the power cable! where have you routed the cabling, a rough guide as some cars are different; power cable down left side of car with main loom, rca/remote on down middle of car, and any speaker cables down the drivers side of floor! have you followed all of that? i know people who have run the earth along with the power cable direct from the battery and then complain of alternator whine. its no wonder as the earth is acting like a big ground loop ariel for any noise it chooses to pick up!

[ Edited Mon Jun 21 2004, 02:18PM ]

[andy 0]

Created a bracket which is bolted to the rear seatbelt mount in the boot, so think earth is good. Have power cable on lhs of car, remote on and speaker cables down the middle. Earth on its own in boot. Incidentally I have a bass enclosure with a built in amp that doesn't pick up any noise that I have noticed, I have just moved the connections over to this new setup to test it and its sh*te!

[Guest Olly_K]

does the noise get higher pitched when the engine speed gets higher ?

if so then your alternator is to blame

[dubloke 4]

think the seat belt mount is still fixed to a painted panel, but not sure on the difference between 3/5 doors! poor quality interconects could be to blame as the alternator already has a suppressor built in! try earthing the amp to a different part of the boot thats clean of paint. if its doing it on a sepaerate setup to then its gotta be a wiring fault somewhere! the earth should really be fixed directly to the chassis not a bracket thats then fixed to the chassis, the more connected items the greater possibility of interference.

[ Edited Mon Jun 21 2004, 05:37PM ]

[ Edited Mon Jun 21 2004, 05:39PM ]

[madmonkee 0]

sounds like earth problem, what you want to do is earth it to the l/h/s of the boot. Rip off that foam stuff and there is a pannel behind there just waiting to be drilled and rubbed down to make an earth. Same on r/h/s, but near the fuel pipe so be carefull

[Pittuf 0]

If you look under the rear seats there are a couple of earth points ready made, just unscrew them and hook it up, thats what i've done and i've had to problems whatso ever :-)

[andy 0]

cheers, will try that

[andy 0]

ok, have tried alternative earth arrangements, no difference noticed, the buzzing noise does follow the engine speed, I have disconnected the alternator and it still does it, wondering about my ignition leads now, they're probably the origninal ones ie 10 yrs old, have measured the resistances as 5k as expected but don't know if they have built in surpressors?...anyone... all sugestions appreciated

[ Edited Fri Jul 02 2004, 05:06PM ]

[andy 0]

got there eventually, have bought an inline supressor for the head unit and this has pretty much cured it, gonna put another one on the amp supply and reckon this will completely cure it... cheers for help peeps, incidentally got the supressor from Maplins, it was £4.99 which beat the halfords version by £20!

[Pittuf 0]

Glad you got it sorted mate :-)