As long as you can adjust the gain on the sub's amplifier, there's nothing wrong with going "big".

Well.... maybe. Disclaimer: The following is based only on my own personal experience, not on any research or information from people who know more about car stereo than I do (about 90% of all the people on the planet, I would guess...)

I have found 10" subwoofers to be more responsive and less atonal than 12" (or larger) subwoofers. Now, that may be because I run my single 10" sub full range, and as a result produce quite a lot of mid-range sound (100--500Hz) from my sub. The 12" subs I have heard seem to be dark and atonal, that is non-melodic. Just "blump blump blump" sounding. Even if those "blumps" are crisp and tight sounding, the fullness, richness of sound isn't there.

However, since my car has been called "...a freak of acoustics" by my stereo installer, I can't recommend that you run your subs full-range (i.e., not crossed over). According to most knowledgeable people, my system should sound terrible the way I run it. (It doesn't -- I have the trophies to prove it! :-) But if I ran my sub crossed at 90 Hz, maybe I would think it was atonal just like the 12's I have heard.

The downside of a 10" sub is that it it won't play as low a frequency as a 12". I'd guess the 12s will go about half an octave lower than the 10s. However, there is a clever workaround for this that, even as I write this, my stereo installer is working on for my new car. The lowest frequency that a speaker system will produce is not a function of the diameter of the speakers; it is a function of the total cone area within a single enclosure. So a pair of 10" subs in a common sealed enclosure has the same amount of cone area (157 square inches) as a single 14" subwoofer (154 square inches) and will produce the same low frequencies as the larger sub. It has the further advantage of being able to produce the higher frequencies and brigher sound of the 10" that a 14" couldn't produce. (Not that there is any such thing as a 14" subwoofer, but you know what I mean. :-)

Finally, I'm not sure I would put a pair of 12" speakers in an MGB, just on the off chance that I might want to save room in the trunk for a bag of groceries or a pair of hiking boots or something. A pair of 10s could be packaged in about half the volume of 12s.

Having extra power in reserve is a good thing.

By "power", Tony is referring to the amount of sound producing capacity you would have with the subs, not the amount of watts from the amplifier. Both are good things to have more of than you need, because remember just because you have it doesn't mean you have to use it. It's really easy to turn the gain down on the subs if there's too much. It's real hard to turn it up if there isn't the capacity to have enough.

So, at the end of this rambling discourse... if it were me, I would go with two 10's in a common sealed enclosure with plenty of "headroom" in the amplifier to drive them. I'd try them both crossed over, and full range to see which I liked better.

Be sure to tell us what you did and how it worked out.

tanstaafl.

"There Ain't No Such Thing As A Free Lunch"