Due to popular demand I have decided to do a top boost version of the AC20. Top boost refers to the addition of tone controls to the circuit. Typically when we add tone controls to an amplifier we are NOT ADDING tone but rather SUBTRACTING it. As we turn down our tone controls we diminish the output from the amp. To compensate for this loss an extra stage of gain needs to be added to increase the volume back to its original levels before the tone controls were added. That is why it is called a top BOOST.Available in head or combo form. The best of the top boost circuit in an easy to use 20 watt package that is the perfect combination of clean head room and sweet compression. Slightly more gain than the AC20.