The element germanium was the first semiconductor material used in the making of transistors. It is, however, a quirky and temperamental substance, and while it has largely been superseded by silicon devices, germanium transistors are still made and have properties that the original Sola Sound MkII circuit used to advantage. Germanium is not as temperature-stable as silicon, and the increase in free electrons as germanium warms up as part of the Tone Bender circuit affects how the device sounds.
Silicon is essential to the development of transistors, integrated circuits and the computer age. When manufactured with sufficient purity into crystals, this second-most abundant element on Earth is an ideal semiconductor for the creation of transistors. When comparing the behavior of silicon and germanium transistors, silicon is more reliable when temperature stability is important, but many prefer the soft clipping sound of germanium.
Standard transistors are made in two types, referring to the layers of semiconductors used. These are described as NPN and PNP types. Every transistor has a connector to each of the three layers, called the base, emitter and collector. While the NPN type is more common due to being easier to manufacture, the PNP type is the transistor design that is used in the Tone Bender circuits and its variations, in either germanium or silicon form.
Colorsound has two models available with the Tone Bender name. Both are marked with the description "FUZZ" on the case, The white-cased Tone Bender uses three silicon transistors and is described as a hybrid of 10 of the best-sounding vintage 1970s units. While Colorsound gives no specification of the specific transistors used, do-it-yourself re-creations suggest PNP silicon transistors like 2N3906 are used. The yellow-cased Tone Bender uses two vintage BFY71 silicon transistors for amplification and one NKT214 germanium transistor for its soft-clipping distortion.