Hi: When the temperature drops below approx. -15 celcius (-7 F) I get an engine whine from my rear speakers. Never the front & I will hear the whine even if the fader is set to front speakers only.

This problem doesn't happen when the temperature warms up, above approx -5 C (20F).

The only other problem with the system is the radio antenna has seized (frozen) in the up position, well two segments are up.
Thanks

91 740 & 940 T's

In the cold, system voltage rises from around 13.0-13.5 volts to around 14.0-14.5 volts. And (and I speculate) the ripple from the alternator increases (ripple = whine).

The power supply filtering -- internal to the amplifiers -- might be marginal.

Install a big mutha choke followed by a big mutha capacitor on the power lead feeding that amplifier.

The choke goes in series with the power lead; the capacitor goes between the power lead and ground (+ tab of the cap goes to the power lead, - tab goes to ground). I would install the cap between the choke and the amp. In your shoes, I'd look for a capacitor with a rating of about 2,000 mfd to 5,000 mfd @ 30 volts or higher.

Also be sure the signal leads going into the amplifier from the tuner are shielded and grounded. (They should be grounded at one end only to avoid a ground loop.)
--
Don Foster (near Cape Cod, MA)

Thanks very much for the info.

I loved the picture of your ign. wires in the dishwasher.
Reminds me of the time my mother caught me w/ my motorcycle cylinder head in the oven. It worked great for replacing valve guides. She wasn't very happy.

Thanks Ian