Maxon TBO-9 True Tube Booster/OD Pedal

• Clean Booster/Overdrive pedal with Tube gain stage
• Employs mil-spec sub-miniature vacuum tube
• Great as a tube amp booster to add warmth
• Boost knob controls level of tube gain
• Dual-purpose Drive control with clean blend function
• Internal voltage regulator runs 30 Volts to tube
• Heater In-rush current control warms tube upon power-up
• True Bypass Switching

The TBO-9 combines Clean Boost and Overdrive capabilities with a tube gain stage to create a versatile tone-shaping tool.

The ideal complement to non-master volume tube amps, the TBO allows you to drive a clean or semi-clean amp to the breaking point, giving it that “on 10” tonality at a much lower volume level and without altering the amp’s signature tone.

The TBO-9’s tube stage is controlled by the Boost knob which adds a fat, warm bottom end with a slight mid bump as it increases the output level.

The Drive knob blends clean and distorted signals, allowing the user to dial in a small amount of grit with minimal coloration.

The TBO-9 features internal voltage doublers that bump the incoming 9 VDC up to 30 VDC for massive headroom and maximum transparency.  

When you need to drive your amp without driving the audience towards the door, the TBO-9 does the job without commanding the center stage.

The TBO-9 is the perfect complement to non-master volume tube amps, boosting level and drive while retaining maximum transparency.

TECH TALK:

The basic TBO-9 circuit architecture is very similar to the Maxon OD820, including the dual-function Drive pot that blends clean and dirty signals while increasing saturation.

The circuit starts with a tube gain stage featuring a mil-spec 5703WB JAN Raytheon sub-miniature vacuum tube positioned at the front of the audio path.  This tube stage does not provide any distortion, with the exception of overdriving the input of the clipping op amp.

After the tube gain stage, the TBO’s secondary gain section features a dual-stage clipping design that combines the classic “808” clipping (diodes in feedback loop) with a pair of diodes to ground ala’ the SD-9 and RAT.  This design effectively clips the signal twice, and the round smooth clipping of the feedback loop followed by the edgier diodes to ground adds a slight “chewiness” to the pedal’s overdrive voice.

The TBO-9 features internal voltage doublers that bump the incoming 9 VDC up to 30 VDC for stable tone with massive headroom and zero harmonic distortion.

The TBO also features Maxon’s In-Rush Current Control system - As soon as power is applied to the pedal, a small current is applied to the tube and begins heating it at a very low voltage (much like a tube amp standby switch) - This system dramatically extends the tube life.

The TBO-9 features Mechanical True Bypass switching via a Fujisoku 4PDT switch.

NOTE ON POWERING THE TBO-9 - this pedal’s voltage regulator IC requires a high inrush current of approximately 2000 mA upon startup.  When using with a Power Brick such as the Voodoo Labs Pedal Power 2+, this pedal should be connected to a high current power jack when possible.

Input Impedance: 500K Ohms

Output Impedance: 10K Ohms or less

Maximum Gain: 52 dB (1.6 KHz)

Equivalent Input Noise: -110 dB or less (IHF-A)

Control: BOOST, DRIVE, TONE, LEVELSwitch: BYPASS/EFFECT (mechanical TBS)

In/Out: INPUT, OUTPUT, INVERSE OUTPUT

Indicator: BYPASS/EFFECT LEDInternal Circuit Voltage: 30 VDC (DC-DC Converter)

Current Consumption: 270 mA / 9 VDC

Dimensions: 74 mm (W) x 124 mm (D) x 54 mm (H) / 2.9” (W) x 4.9” (D) x 2.13” (H)

Weight: 560 g