prestonmcafee

I put a Lowrance GPS system in my 2001 Cabriolet. It plays MP3s, so I hooked it up to the auxiliary input on the Porsche/Becker CDR-220. I get some alternator whine (annoying but not absolutely horrible), in spite of having a ground loop isolator on the input wires. Moreover, I get about the same level of whine even if the Lowrance unit is off. I only get the whine with the aux, no whine on CD or radio. I tried moving the wires but this didn't make a difference (but the possibility of this is limited due to the location of the back of the radio).

Any ideas?

prestonmcafee

I moved some wires around, and managed to reduce but not eliminate the whine. When the input device is off but the system is on auxiliary, the whine is *much* worse, but when the input is on but quiet, the whine is pretty small but still noticeable, at least if the lights are on. I haven't tried a noise suppression kit yet, but that is the next thing I came up with to try, based on reading the forums here and elsewhere.

ltc

Would you happen to have BiXenon (i.e. non halogen lamps)?

Is the whine the same/different with headlights on/off?
Is the whine the same/different engine on/off?
Is the whine the same/different wtih engine on/different RPM's?

What connector is used to go from the CDR to your 'aux device'?

Have you tried removing the 'ground loop isolator'?

prestonmcafee

The whine is worse with the headlings on. I think the lights are the xenon lights. There is no whine with the engine off, and it does vary with RPM. I bought the aux connector from the company in NJ that supplies Becker parts, I forget their name. I haven't removed the ground loop isolator yet but I will; if I remove it, I need a micro plug to male RCA plug connector, which I think I have somewhere but haven't yet turned up.

I put a 12 volt isolator in today. This further reduced the noise when the auxiliary device is on, but, oddly, increased the noise when the device is off. (I don't care about this increase, however.) The noise is now low enough that it doesn't bother me -- I have to turn the volume very high to make it annoying.

prestonmcafee

I tried removing the ground loop isolator and it make the problem marginally better.

ltc

Ground loop isolators are normally a waste of money.

It sounds as though you have 2 sources of RFI; the inverters in the headlamps (very common) and ignition/spark plug (may want to check to see if you are running OEM plugs or not).

If it's now acceptable to you, then enjoy