fender mtg tube distortion vs bk butler tube driver

The 4.7 nF capacitors C 11 and C 12 are used to dampen the switching transients preventing the JFET from switching in nanoseconds. The JFET control signal is applied through 1 M Ω resistors R 16 and R 47 protecting the gates from high current peaks. To do this the diode can be reverse-biased applying 9V to the gate control pin (cathode), the resistance between drain and source will go down to the lowest possible value. In order to turn off the JFET, the gate control voltage must go down almost to 0V. The capacitors C 11 and C 8 at the input and output side keep the JFET DC conditions isolated from the rest of the circuit. To do this V G must be grounded, being more negative than the V D and V S and forwarding the diode. The drain and sources are biased to 4.5V with high value 510K resistors R 18/R 17/R 12. Note that V F is the forward voltage of the diode. If the diode D 3 or D 4 is forward biased, (gate control voltage is at least V F more negative than the pinch-off voltage of the FET) the switch is off and the FET presents a high impedance.If the diode D 3 or D 4 is reverse biased, (gate control voltage is at least V F higher than most positive input signal amplitude) the JFET switch is on and the signal passes through.The essential part of their operation is to control the biasing of the diodes D 3 and D 4: The switches are implemented with an N-channel JFETs working in saturation/off mode. Buffering the guitar signal avoids tone sucking, this is the reason why some players place the Tube Screamer early in the pedal chain before other pedals without input buffer as the Wah Wah, and therefore keeping sound fidelity. In both states, the signal always passes through the input and output buffer, so it will work as a buffer even whether the effect is bypassed. The signal will skip the core of the effect but it will still pass through the input and the output buffer. To bypass the effect: Switch A (Q 2) is off and Switch B (Q 4) is on.The signal will pass through all the effect stages. To activate the effect: Switch A (Q 2) is on and Switch B (Q 4) is off.The JFET Bypass is formed by two switches and a toggle block to manage these switches: It can turn the effect on, routing the signal through the circuit core or turn it off, bypassing the pedal and keeping the guitar signal unmodified. The original TS808 Tube Screamer is not True Bypass, so it needs a JFET Switch Circuit in order to activate/deactivate the effect using a simple push button. The Distortion knob controls the level of overdrive, the Tone setting adjusts the amount of treble and the Level knob controls the output volume of the pedal. The pedal has three knobs: Distortion, Tone and a Level. The JFET Bypass Switch task is to activate/deactivate the effect and the Power Supply stage provides energy to all the circuit. Finally, the Output Buffer will prepare the signal to be injected in other pedal or amplifier. Then, the Clipping Amp stage incorporates the distortion to the signal and the Tone/Volume block will add the tonal bass/treble adjustment. The functionality is simple: The input buffer isolates the pedal from the guitar, keeping the signal fidelity.

The Tube Screamer circuit can be broken down into some simpler blocks: JFET Bypass Switching, Power Supply, Input Buffer, Clipper Amplifier, Tone/Volume Control and Output Buffer. Table of Contents:ġ.4.3 High Pass Filter in the Feedback Loop.ġ.4.4 Low Pass Filter in the Feedback Loop. This article is focused on the first design, which is considered the most attractive: the Ibanez Tube Screamer TS808. The circuit was designed in 1979-1980 by S. Tamura, a Japanese Engineer working for Nisshin Onpa/Maxon, an Original Equipment Manufacturer for Ibanez.ĭue to the pedal success, several versions and reissues were released over the years with small circuit variations. The clever schematic is easy to understand and prone to modifications. In terms of electronic design, the hit of the pedal remains on how the signal is filtered and distorted over the stages. The frequency response is tailored to emphasize the mid frequencies, creating a hump that helps to keep the guitar sound over the general mix of the band. It is suitable for blues and all range of rock music, adding a classic standard tone characterized by the tubelike distortion, good sustain, and smooth overdrive. The Tube Screamer TS808 by Ibanez is the most famous overdrive guitar pedal.

Fender mtg tube distortion vs bk butler tube driver