Can a home sub go into a car?

There are some slight differences in the drivers, but they will still work.  One of those difference is the impedance as you mention.  The other difference is usually home subs have a lower resonant frequency (fs).  This is because the larger rooms don't have as much boost in the low end like cars do.  This means they need more help to produce lower frequencies, and therefore usually have a lower fs.  Home subs are also usually designed for larger enclosures as space isn't as much a premium. 

The higher impedance just means that your amplifier won't produce as much power.  But since power is cheap now, it's really not that big of a deal.  I would say go for it.  Many people have been very successful using our home theater subs in cars. 

Steven Kephart

Adire Audio

Yes, but now the opposite is true.  The car sub might not have enough low end in a home theater.  Of course if you know what you are doing, there are ways of fixing that.  For one thing, you could add a specific amount of mass to the dustcap, which would lower the Fs of the driver.  But efficiency would also be lowered.

BTW, if you are looking for something to add mass, my boss has found that Silly Putty is extremely consistant with weight.  His partner works over at the college where they have molecular scales.  They have weighed several eggs of silly putty, and they were all the same weight down that far oddly enough.  That's what we use to test parameters on speakers.

Steven Kephart

Adire Audio