Audio Systems: Radio Sound Lose, market radio, power amp

Question
Hi Tom,

I wonder if you might be able to help me out. I just installed an after-market radio. There is only one problem that I have noticed.  When I am driving, the sound is perfect, but when I am slowing down, the sound starts decreasing, probaby like 50% by the time I stop. When I start driving again, the sound starts going up again.  I have been looking around trying to find an answer, but haven't been able to.
Can you please help.

Thanks,
Robert

Answer
Robert,
Do you have a power amp installed also? The problem may be due to the radio and amp not getting enough power to operate with the engine running slow. It could be that the alternator isn't putting out full voltage/current at slower engine speeds, but it does when the running the vehicle at higher speeds? I have also seen on some stereos that they have a circuit when turned on will increase to volume at higher speeds so you can hear the stereo with the windows open or the top down. Please give me the make and model of this stereo and I will research this problem more for you.

TOM,
T&D ELECTRONICS