Hi:

How are you? I am (hopefully) nearing the end of a 3 week sound system / sound deadening installation. It seems I have run into a huge problem I cant solve!

A ton of noise is being picked up and amplified through the amp/speakers. I have the noise with the engine off. Just ACC on, the noise appears. With the entire car ON, the noise is there. Further, when the A/C starts blowing, the noise is clearly evident and increases with the speed of the fan.

What the heck is this?? I have tried plugging in a friend's ipod via RCAs into the amplifier (Reference 7541a), there is NO noise. I have regrounded the head unit (Pioneer AVIC D1) with no success. If I touch a ground to the outer shield of the RCAs, the noise drops significantly - but not completely.

Can anybody provide any input to the cause of this??

Thank you very much, any help is greatly appreciated!

THKS,

Jeff

 

Sounds like you're on the right track with grounds. It's best to have one central solid ground which attaches to the uni-chassis. You have to clean the paint off this point and run a bolt into this location - or use one of those grounding blocks which attach with three screws. From this point run good size wire out to your amplifiers (this guy should be as short as possible) and then smaller wire (like 8 gauge at least) out to your headend and brain unit.

Doing this isn't going to do any harm.

 

Thanks for the reply. I have a basslink and the 7541a wired to a ground distribution block via 8 gauge, and the dist block grounded to the chassis via 4 gauge. It is very securely anchored to the middle piece of sheetmetal between the two compartments between the seats. I then have the head unit grounded to a thick piece of metal beside the head unit.

Can the piece of sheet metal be "too thin" for the 4 gauge wire? Or is the two grounding points (amps and head unit) causing a ground loop?

Im not sure if this is a ground loop problem or not. Can I ground the head unit to the ground dist block? Or should I get a ground loop isolator?

Thank you so much!!

 

If you have a volt-ohm-milliamp meter you can measure the difference between the two grounds if you'd like. It's probably just as easy to run a nice 8 gauge wire between the headend and your main ground point.

The idea is that you want any current between those two points - the headend and your amplifier to be flowing over that dedicated ground cable not though your signal (RCA) wires.

AudioControl has a tech note #12 that covers ground loops. They state that 90% of noise problems in cars are caused by ground loops.

You've already answered their first question on the flow chart - unplug the deck audio and radio antenna from the system and listen for noise. Your noise stops so they say "run ground wire from deck to common star ground" - dang they're smart ... that's what I said!

ETA: try this first and not the ground loop filter.

 

Hi!

Well, its dark out, but I went and tried a couple things. I unscrewed the ground from the headunit that I made behind the deck, and ran a 16 gauge wire between this and the amp ground dist block. I couldnt tell if it made any difference - there was still tremendous noise. 16 gauge is the largest i have right now.

I then added a ground to a bolt I found on the firewall - and the noise definately dropped at least 50%. This was using a 14 gauge wire, approx.

I guess I will run over tomorrow and get some 8 (right?) gauge wire. There are two ground wires coming out of the head unit - both of which are maybe 18 gauge in the harness provided with the unit. So - is 8 gauge correct - or should I be looking at something like 12 gauge?

Finally - should I ground the head unit behind the head unit AND to the ground dist block? (effectively adding a ground between the current ground and the ground dist block) ... or ONLY to the ground dist block?

Thanks so much for your help - glad to see there is hope in the near future!

THKS again,

Jeff

 

This is becoming extremely frustrating!! Any suggestions would be much welcome and grateful!

I have since run new power and ground to the head unit from the distribution blocks used by the amplifiers. The only wire not new was the ACC wire - which was not fused so I assume is used only as a turn on lead. Noise remains with boht new power and ground.

I then grounded the headunit directly to the battery - no luck - noise remains. All wires are 10 gauge.

I checked again plugging ipod into the amp via RCA, works perfectly, sounds great!

What in the world is wrong with this thing?? Please provide any assistance possible.

Thank you!

Jeff

 

are your rca and power wires runing down the same part of the car? If they are then thats no good. try spreating thesr wires so their not close to each other like one down drivers side and one down passenger side. It sounds like your getting feedback thru your rca? give it a try.

 

Run on complete different sides of car.

I jsut picked up a ground loop isolator - it did remove the problem but it completely killed the quality of the sound. Sounded terrible.

Please anybody help!!

 

you can ground the outer metal ring of your RCA cables and ditch the ground loop isolator, also check where you ran your power wires and if you used shielded rca cables or not.

if you have multiple rca connections this is also a problem for noise. meaning connecting your audio out to an rca to an adapter near the source... multiple rca connections is no good and a cause for noise.. I don't know thinking out loud to try and help you out.

 

Oh man - you wont believe this! It looks like there is some type of loose connection on the actual plug of the harness provided by Pioneer. For some reason, this wasnt a problem with the internal amp, but now it is with preouts. Either it is the conenctor for the preouts or the main power/ground/etc. connector. Havent determined which yet - but I have narrowed it down to this! Wow!

Does anyone know where I can get some replacement connectors for the D1?

Thanks so much for all of your advice, Ill let you know what happens