I recently found out that a fellow sound engineer has a pair of QSC Ksub (dual 12″ band pass) subs. Owning a pair of QSC KW181 subs myself, I thought I would compare and measure the two boxes.

This is a spec sheet comparison of the relevant points.

QSC – KSub specs
QSC – KW181 specs
This trace is of both subs with the input level set to unity, positive polarity and contour switch set to normal.

This trace is of both subs with the input level set to unity, positive polarity and contour switch set to deep.
The smaller KSub (2×12″ bandpass) and KW181 (1×18″ front loaded) are for all intent and purpose, matched! I’m not sure if that speaks well of the KSub or poorly of the KW181. The KW181 does play a bit lower but the difference is small. Judging by the manufacturer specs the KW181 should be able to play 5dB louder than the Ksub but I’m unwilling to verifying that claim due to the sacrificial nature of the experiment.