EWS Effects EWS Bass Mid Control 2 provides +10db of gain at the input stage. Its Frequency adjustment controls the frequency range between160Hz to 2.5KHZ, while the Middle control boosts or cuts those frequencies by +-12db. The EWS Tri-Logic Bass Pre-Amp III adds features including gain or clean-boost modes, frequency adjustments for Treble and Bass, and 9- or 18-volt operation. Visit www.ews-us.com.