The Ultra XL module is a modern version of our legendary hi-gain tone. The Ultra XL has massive amounts of liquid gain combined with huge bottom end and cutting upper mid-range. All modules utilize the same panel layout, which includes Gain, Bass, Mid, Treble and Master controls, with a bright switch included directly under each Bass control. Each preamp module houses two 12AX7 tubes which can be easily changed or replaced. Use the thumbscrew to remove or secure each module to the front panel of every MTS amplifier.