I have my car in a shop right now and they are saying that the MINI (BMWs) are prone to some audio whine. As demonstrated by the installer (using a stethoscope like devise), all speakers and amp (JL audio) were disconnected from the head unit. No power to the amp, but the power cable was still connected. The installer checked all power cables, rca's, etc. and showed me that everything is installed correctly (proper grounding, etc.). The installer even tested a different head unit and the whine is still there. So, we ruled out the existing head unit (Pioneer).

What we discovered is there is still a slight whine coming from under the battery compartment. The whine gets amplified after powering up the amp, but can be dialed out of the speakers using gain control. However, the whine still remains present even though it's not coming through the speakers.

Any thoughts or suggestions are greatly appreciated.

 

I suggest you turn up the volume on your stereo. There are gremlins hiding in your mini, and they will leave if you are consistently louder than them.

Do you have to have a stethoscope to hear it? If so, you don't have a problem.

Perhaps there is a whine in the shop.

Sorry that all my suggestions are silly, but your conundrum has me stumped.

 

I heard a whine comming from my radio, but it was just country-western music, I changed the station and it was all fixed!

Dave

 

The stethoscope like device was used to isolate where the noise was coming from. You can hear the whine without the device.

 

That whining noise can be anything. Usually its interference from a electric motor of some sort usually the alternator. But our cars have other electric motors as well. Have they tried a noise isolator yet?

 

Yeah. They tried the ground loop isolators, but it's still there. Are there any electrical motors in the rear of the MINI?

 

One thing I forgot to mention;

My car was recently in for service for a radiator fan replacement. When I got the car back, the whine noise was gone. At first I thought, nahhh can't be! The stereo was off, as the service required disconnecting the battery. Since it was off, I never turned it on. The whine was completely gone. Got home, turned the car off. Went back out later to drive into the city and no whine. Again, I had not turned on the radio. I was enjoying the whine free ride. As you might expect, the second I turned on the radio, the whine slowly came back.

This is the reason why I having the installers take a second take at eliminating the whine. It's got to be in the stereo wiring or grounding, but it's definitely not related to the MINI.

 

While doing more research on how to resolve this, I came across a couple of responses from MINI owners that stated to put a capacitor on the alternator. What does this mean? Has anyone done this? If so, details please...

 

A capacitor would act like a stereo crossover and filter the specific frequency of the tone you are hearing through the speakers, if it is coming from the alternator.

But, that just maskes the real cause. Normally, there is not enough ripple voltage to cause radio noise. But, there are two conditions that can cause an increase in ripple voltage and radio noise: these are diode failure and increased circuit impedance.

So, you may have a bad diode in the alternator, or bad connections between the alternator, battery and your radio, causing high impedance (resistance).

Dave

 

I think I get what your saying here. Could that explain why there was no whine after service (with radio off), then whine is introduced after power is introduced to the stereo? Not sure if I'm making any sense or not... Thank you for the advice.

 

Are the signal cables and power cables ran next to each other? They should be run on opposite ends of the vehicle.

 

No. Wires are running on passenger side. We even ran the wires outside the car, but still had has a slight whine.

 

Update:
The whine only appears after the amp is turned on. The whine is now been minimized significantly, but is still present. The previous isolation was resolved by disconnecting the battery and allowing it to sit for an hour.

Another suggestion was to use a capacitor. Any idea what farad rating? Polarized or not? Sorry for all the questions, but I'm new to this.

 

Most shops will use a 1 farad or 1.2 farad. I have seen higher numbers but I don't know that they are necessary. I had a Tsunami cap in an old car. You run it between the alternator the battery (in series I think, but you should ask the shop, or someone else).

 

I've had a whine that was caused by a bad capaciter in the amplifier's power supply, but that was in a home stereo. Just an idea.

Dave

 

Thanks.

 

Sometimes, it is caused by an old set of ignition wiring. Change to a new oem set or to a 8.5mm set.

 

Caps are ran in parallel with the battery/amp. It acts as a buffer for high draw amps. http://stason.org/TULARC/entertainme...s-it-work.html

 

A cap will do nothing for you in terms of alternator whine. Try switching out the amp or try new RCA cables. I'd also make a new ground for the amp.

 

try a line driver like the AudioControl 'Overdrive'. About $120.

 

You may check if the sound is being generated by the fuel pump. If you have your amp mounted in the rear it may be picking up the RF from the Fuel Pump Motor. The grounds on the early 1st generation MINIs are really minimum. Adding a few all over can't hurt?

 

Sound drive/line driver is the way to go. I bought one for all my RCAs and it completely eliminated the really loud whine.

 

My e30 and e36 were both notorious for engine whine with aftermarket stereo equipment. I've been down that road spending countless hours and having the best local shops diagnose the problem to no avail until trying the line driver. I think it's just inherent in how BMWs are built. Good luck and let us know what works.

 

Late response, but I thought I should update.

After installing the 1 farad capacitor, the noise has been eliminated. The capacitor fits nicely behind inside the passenger side rear compartment. Now I'm enjoying a whine free ride!

Thanks for all the advise and suggestions.

 

Hey MadMike, how did you place the capacitor? Between battery and ??? In series or parallel? Is the noise still absent??

Thanks