AC-JB20-XFMR Add a transformer to any low impedance speaker. 20 watt 25/70.7/100 volt transformer inside a junction box. Tap settings include 20 W, 10 W, 5 W, and 2.5 W (2.5 W tap not available on 100 V setting). (25 Volt only: 2.5 W, 1.3 W, 0.7 W, 0.4 W).