All samamp guitar amplifiers are point to point hand wired with "class a" vacuum tube circuitry. The V.A.C. - Variable Amplitude Clipping control (patent pending) is the central feature setting operating parameters of the output tubes. The point at which the output tubes clip is sometimes called the sweet spot. This is volume compression and output limiting at its best. How loud the amp is at clipping is determined by its output power. The most common way to reduce power to the speaker is with an attenuator. These are placed in the signal path between amp and speaker. Only part of the output power reaches the speaker with the excess converted to heat. The V.A.C. circuit is a different way to control the output power of a tube amplifier. Not a built in speaker attenuator and not in the signal path, the V.A.C. rewires the power tube circuitry and changes the amount of output power produced.  V.A.C. uses lamps (light bulbs) to limit voltage and current flow into the power tubes. This balanced circuit changes the power rating of the amp and allows voltage to sag the optimum amount. Power tubes run cooler with V.A.C. and all of the output power reaches the speaker. 

All models have several output power presets and use readily available lamps: 15 watt exit sign, 7 watt "night light", and 4 watt "night light". It is possible to increase lamp values and change the power level of presets using the higher wattage lamp. One can take advantage of the "feel" and touch sensitivity that coincides with the volume compression and output limiting of power amp clipping.