To create its lush overdrive tone, the TBO-9 blends this subminiature tube stage with a solid-state distortion circuit. Unlike other tube overdrives, the TBO-9 employs a unique 'pre-tube' circuit configuration, where the tube comes before the solid-state distortion circuit in the signal chain. By cascading the tube stage into the distortion stage, a more realistic tube-amp tone is achieved. The result is a warm yet powerful guitar tone that is extremely interactive with the player's performance and responds exactly like a hard-working tube-amp.

Maxon's TBO-9 overdrive effects pedal features a US Military spec subminiature tube at its core. Subminiatures are the final frontier of vacuum tubes, as the supply of quality vintage tubes is rapidly dwindling. Used extensively during World War II, subminiatures were largely abandoned by 1955 in favor of transistor technology, leaving a healthy stock of quality NOS product behind.To create its lush overdrive tone, the TBO-9 guitar pedal blends this subminiature tube stage with a solid-state distortion circuit. Unlike other tube overdrives, the TBO-9 overdrive pedal employs a unique "pre-tube" circuit configuration, where the tube comes before the solid-state distortion circuit in the signal chain. By cascading the tube stage into the distortion stage, a more realistic tube-amp tone is achieved. The result is a warm yet powerful guitar tone that is extremely interactive with the player's performance and responds exactly like a hard-working tube amp.The Maxon TBO-9's circuit features a clean Blend function built into the Drive control. At zero Drive, the TBO-9 passes clean signal only along to the Tone and Amplifier stages of the pedal. However, this clean signal is fed from the tube section of the pedal, whose gain can be adjusted via the Boost control. As the Drive control is increased, the solid-state distortion circuit is blended with the tube-driven clean signal. In this manner a wide variety of clean boost, semi-clean, overdriven and fully distorted tones can be achieved simply by manipulating the pedal's Drive and Boost controls. Both the tube and solid-state sections of the circuit are fed with 30 volts DC thanks to the TBO-9 pedal's internal voltage regulators. Running the circuit at higher voltage provides a more consistent tone with increased headroom and dynamic response. The performance of the tube is kept stable and reliable thanks to Maxon's unique heater inrush current control, which feeds the tube with a lower startup voltage to extend tube life. The

The TBO-9 True Tube Booster/OD utilizes the same "pre-tube" configuration as the TOD-9. However, the TBO-9 also features the Dry Blend feature found in Maxon's popular OD820 and VOP-9 overdrives. The Drive Control has the dual function of increasing saturation and blending clean signal in against the distorted sound. At zero, the TBO-9 is passing pure clean tone, but this signal can be altered using the Gain and Tone controls of the pedal, effectively creating a tube preamp/booster. As Drive is increased, saturated signal is blended in against the clean tone, realizing a 50/50 mix at the 12 o'clock position. At fully clockwise position, the TBO-9 acts as a tube overdrive, much like the TOD-9. Using the TBO-9, a wide range of tube booster/overdrive tones can be achieved, all of them yielding the warm, organic tube tone that every guitarist craves.