Hi folks,

I recently upgraded my 2009 Dooper Clubman with Focal 6.5 set in front and 8" active sub in boot (in spare wheel well). I purchased RCA kit from Newministuff with RCA connections and remote power lead (loom was perfect quality, highly recommended). I used Double shielded RCA cable running in left, drivers side whilst power lead and sub remote cables in right of the car.

Power lead is direct connection to car's battery on 19mm nut.

When I have ignition on, or the car is running, subwoofer is generating constant hum which can be turned down with GAIN control. Removing either left or right RCA cable from sub will decrease hum and removing both will make it go away.

Grounding is top quality mind me saying and there should not be any issues regarding connections etc. I like to do everything with my car to perfection and I don't use quick fixes with connections etc so I'm a bit puzzled.

So to recap:

- RCA cables running straight from stock radio loom, Mini Wave radio (base)
- RCA cable runs from left hand side, power and remote lead on right
- Sub is powered straight from battery with adequate lead
- Ground connection is straight to car body, bare metal exposed
- RCA lead is double shielded and normal quality
- When only radio powered, no hum, perfect sound
- When IGN on or car running, constant hum from sub, all other speakers are working normally and without any side effects

Please help - could my issue be the battery connection? Should I use other terminal on car to minimise interference? Any other ideas?

Jani, Finland

 

I'd try another ground location first. I have mine hooked up the same way with ONE exception, I tapped into the speakers via the harness in the driver's kick panel. I'd guess it's either that....or bad one/combo of Line Output Converter/Amp/RCA Cable.

 

Had a different car...non mini...had a buzz that would not go away...turned out the alternator was iffy...when it got swapped out...the buzz went away. Not saying it is your issue, but sometimes stuff can go beyond the basics....

 

If you can't adjust it out using the gain control try a ground loop isolator for the RCA Connections by Stinger Or a power noise supressor by Pyramid.

http://www.amazon.com/s/ref=nb_sb_no...oop%20isolator

 

+1 on the ground loop isolator...here is a good one:

 

Believe it or not the best results were obtained with the cheap 5 dollar Pyramid power filters

 

Bummer, did not go away with filter from local radio shack.

Could it be remote turn-on lead? Is it safe to steal it from boot light loom?

Edit: with filter hum turned down to some extent, maybe a third or a quarter to put it in scale but still very annoying..

 

did you connected the rca directly to the amp? What amp do you have?

Here is the issue. If you tap the signal from the radio but before factory amp, then the signal is consider as balance. If you connect that to a LOC and from there to your amp, you have noise interference from the engine. I have his high pitch whining noise from the engine, especially when you have the light and AC on. Now if your amp can take balance input, then connect the signal (prior to the factory amp) to the after market amp, then noise go away.

I had that issue. Finally ditch the LOC and connect directly to alpine PDX amp. Sweet to my ear.

Majority of the time, the noise is due to grounding problem. Now if you check and your grounding is good. convert your signal cable (if prior to the factory amp) to male rca and get a good efficient class d amp with balance input. Check out the new JL audio xd series.

i found out this by reading up on bmw forum. I forgot the thread but one of the thread show list of amp that accept balance input.

Now if you tap the signal after the factory amp, get a good line driver. Something like audio control lc6. It does increase the output voltage and off course get rid of the high pitch whining noise. Another cheap solution is to get the rockford fosgate rf-bld. Both work pretty much the same.

Better solution is tap the signal before the factory amp and send it directly to the amp that accept balance signal.

Hope this help.

 

another thing, don't use the ground loop isolator. You lose some good signal. I noticed when trying out the ground loop isolator from schosche and notice the bass more muddy.

 

Have you tried the cheapo Pyramid power filters?
Oddly, I have had the best results with these.

 

sorry, double posted and can't delete.

 

no i didn't try that. seems like a good solution.

I still think better to tap the signal before the amp and use amp with balance input. Really it's night and day different.

If you read up on how balance input work, you understand why. my understanding is that the signal from the + and negative, it sum up and remove excess signal, such as ground noise, etc.

Here is the link..
http://forum.e46fanatics.com/showthread.php?t=528285

 

If you have the factory mini radio (boost or HK ) then there is no pre-amp output as far as I know. I never heard of the wave radio. We don't have any factory radios here in the US that have RCA leads coming out of the back. Do you have a picture of the connectors on the back of it ? If you buy a line out converter which lowers the amplified output to RCA power levels and connections and then put that into the amp it is not the same thing. You are still going to have the radio's amplified distortion going in to the pre-amp input of your amp. This is often a recipe for more engine noise / alternator whine to be introduced into the sound system.

 

i have factory hk hifi option.

i tap it from the front driver side. This signal is before the going to the amp. this is basically just positive and negative wire for each front speaker. Convert that to rca and connect directly to a balance amp. My factory amp is sitting in the rear cargo. So i know the signal is before the amp.

like i mentioned, i have no line out converter. Splice the front and buy rca male connector and convert into RCA output.

 

Sometimes it works well and sometimes it is plagued with engine noise.
Sometimes you get lucky and you can drown out the engine noise by lowering the input gain control on the aftermarket amp.

When I worked at a car stereo shop we sometimes had to try different amps to find a decent match that would not have engine noise as a result.

Engine noise is the most dreaded problem an installer faces when doing systems. We would try all sorts of things like power line filters, RCA Line filters, filter capacitors on the Alternator. (sometimes the factory ones go bad), mesh loom around the RCA Filters and I am not joking when I say that sometimes we had to put aluminum foil around the radio to get rid of it too.