Originally Posted by
EarmarkMarine
ga,
I'm not crazy about mixing a 6.5" and 8" speaker on the same tower. Here's why. The SD (effective surface area) of the smaller XM7 is a little more than 19 sq.in. The SD of the larger XM9 is about 38 sq.in. Doubling the surface area usually results in a difference approaching 3 dB. Side by side I can tell you there is a big difference between the two. To put +3 dB into perspective that is equivalent to doubling the amplifier power. So here lies the challenge. You would need twice the power for the XM7 to reach the same amplitude as the XM9. That places the XM7 in a vulnerable power handling position. Or, you allow the XM9 to naturally dominate the XM7. In that case you have invested alot in additional speakers and power to only have a very modest increase in output. I have to recommend staying with symmetrical sizes whenever possible, especially in a one on one scenario.
David