Our Si Boost is a one knob treble booster designed to kick a hot tube amp on the edge of breakup into an overdriven state. A common tool used past and present by guitarists was the Dallas Rangemaster, a single transistor treble booster that was designed to push an already overdriven amp over the edge and to brighten up the darker British amps of the time. Over the years I have built many Rangemaster clones using a variety of NOS (New Old Stock) germanium transistors but they all have the same problem. The transistors are both hard to find these days and you typically have to sort through a bunch to find the one that sounds just right. NOS components are also not RoHS compliant and therefore cannot be sold in devices. So I set out to redesign the basic circuit using a silicon transistor so that it sounds as close as possible to the germanium units.