How many 6.5in driver equals one 8in driver

A local dealer/builder utilizes single or twin 18” woofers in his custom speaker builds.  These woofers are custom-made for him to be very fast low-excursion drivers.  He claims that his twin 18” models go down to 35 hz.  Truly deep bass is not one of his priorities and he hates subwoofers.

My own speakers don’t go deep either as they are also low-excursion; they utilize twin 12” alnico magnet, paper-coned, pleated paper surround drivers designed to match very fast compression/horn midrange drivers.

Size isn’t all thst matters.

Identical Survace Area ≠ Identical Sonic Performance 

Difference in excursions, materials, execution, etc make a difference.

Size matters when you’re trying to move air.  I have 4 8 inch woofers in each of my Arendal 1723 towers.  Upgraded from the S model with 6.5 inch woofers.  I didn’t use a formula it just made a difference for music and movies. 

This post misses the biggest point in the argument of woofer size, and that’s the room. I had a speaker that sounded great in a 27’ dedicated room, but over powered my new 16’ room. My new speakers have multiple 6.5” woofers which provided almost all the clean bass I wanted, but adding a couple of Rel subs using an 8” driver with a 10” passive radiator provides the bass that I used to have in the larger room. If I would ever build another large dedicated room, my speaker would have many 6.5” woofers or a few 8” woofers with multiple rel subs, maybe even using Rels line array of subwoofers.

The two 6.75 woofers in my B&W 803 D3 in my room did not produce enough bass to sound satisfying. Adding a pair of JL Audio powered subs took care of that, delivering clean, quick, natural-sounding lower octaves that blend  seamlessly with the higher octaves. Careful integration with adjustments of X-over frequency, phase, polarity, and level yielded excellent results.