Amp/Subwoofer Power Questions

[karen]

I have a Sony Xplode 1200W 12" subwoofer powered by a Rockford Fosgate
900W amplifier. I recently moved these components from a Mits. Eclipse
to a BMW Z4. The subwoofer is barely working in the Z4 and the
installers say it's because the power output from the factory Z4 stereo
isn't as strong as the power output from the factory Eclipse stereo.
Could this be true? I thought that's what the amp was for. The
installers have suggested I spend another $60-80 on a "line driver" to
help this problem. Does this sound right? Thanks for any help!

[D.Kreft]

On Dec 27, 10:51 am, "karen" > wrote:

> I have a Sony Xplode 1200W 12" subwoofer powered by a Rockford Fosgate
> 900W amplifier. I recently moved these components from a Mits. Eclipse
> to a BMW Z4. The subwoofer is barely working in the Z4 and the
> installers say it's because the power output from the factory Z4 stereo
> isn't as strong as the power output from the factory Eclipse stereo.
> Could this be true? I thought that's what the amp was for. The
> installers have suggested I spend another $60-80 on a "line driver" to
> help this problem. Does this sound right? Thanks for any help!

I'd get a second opinion. Usually such differences can be made up with
gain tweaks on the amp.

You also need to explain what you mean by "barely working"...do you
mean that you can barely hear it or that the driver itself is
physically not moving very much?

I can't tell right off if the Z4 is a hatchback or if the trunk is
completely isolated from the cabin. If the trunk *is* isolated from the
cabin, you likely can (at least partially) blame the tank-like
construction of your BMW for a decrease in subwoofer volume--there's a
lot of steel (and leather) to block all that acoustical energy your
subwoofer is generating. And if this is the case, then getting the same
volume you had in your Eclipse is going to be next to impossible
without serious effort.

-dan

[[email protected]]

The Z4 probably has a factory amplifier located seperately from the
radio. If the wires were tapped behind the radio it is a low level
signal and will not produce much sound, even through the amplifier.
Especially if a LOC (line output converter) was used. A LOC is
designed to take high level signal (amplified) and drop it down to a
low level voltage suitable for RCA inputs. If the signal is before the
amp, it is weak to begin with and the LOC only knocks it down more. If
the signal is tapped at a speaker, the signal will be stronger, and a
LOC will work properly.
At the same time, Eclipse head units are known for their higher RCA
output voltage. A RCA line level booster may be required to achieve a
desirable output level in this case.