View Full Version : Volume of head unit vs. gain w/added external device

07-31-2009, 11:29 PM
Hello Everyone,

This is a basic question that we don't often think about. But as I'm migrating from my existing factory installed system to an aftermarket installation, I feel I need to get a better understanding of the electronics involved here. I have an old Bose cassette stereo designed for my Acura. It's a head unit with an 80x4 RMS amp attached to the back of the stereo. When you turn up the radio or cassette to the maximum position, it's not all that loud. But when I connect an external cd player with a cassette adapter (dummy cassette) which I've been doing all along, it's so loud that I can't begin to max out the volume without damaging something - either my hearing or a speaker. It's like you suddenly attached an amp to the unit, except portable cd players don't have much of a built in amp.

Now I'm looking at new car stereos and wondering whether a built in radio and cd player will suffer from the same problem characteristic of the radio/cassette in my old system? Will I have to connect my another external cd player to achieve a high output or install a separate amp? On a separate note, I see that most stereos on the market are rated at 50x4 RMS.

Can anyone explain? Thank you

08-01-2009, 12:28 AM
Different media are recorded at different volumes. Newer CDs will usually be louder than radio or cassette. It's up to the listener to tune for whatever degree of gain overlap may provide the best possible compromise based on the most frequently used source and then make further adjustments on the volume dial when necessary.

Head units may have max wattage ratings in the 50 watt range, don't count on more than 15-18 watts rms from most of them.