This slender beauty works like her big sister, the FS?189, also using ?down firing?. That means each FS?187 is equipped with 2 bass ports. One emits sound toward the back, the other downwards onto the base plate. The effect of the actual lengthening of the base port is deeper bass tuning. This arrangement also works as an acoustic low-pass filter. The rear projection bass port comes closed off with a bass control plug. By removing it, bass reproduction can be intensified.