Ibanez TS-9

The Ibanez Tube Screamer is a guitar overdrive pedal, made by Ibanez. The pedal has a characteristic mid-boosted tone popular with blues players. The "legendary" Tube Screamer has been used by guitarists such as Stevie Ray Vaughan to create their signature sound, and is one of the most popular, most copied and "modded" overdrive pedals.

The pedal has a drive knob, a tone knob, and a level knob. The drive knob adjusts gain, the tone knob adjusts treble and the level knob adjusts the output volume of the pedal. The pedal is used to try to mimic the sound of a vintage tube amplifier. The classic Tube Screamer sound includes a "mid-hump", which means that the circuit accentuates frequencies between the bass and treble ranges (mid-frequencies). Some guitarists prefer this sort of equalization, as it helps to keep their sound from getting lost in the overall mix of the band.

The pedal was produced with many variants:

The tube screamer pedal was preceded by the orange "Overdrive" (OD) and green "Overdrive-II" (OD-II). These came in narrower boxes without battery covers. There was also a reddish "Overdrive-II" which had a housing very similar to the TS-808/TS808. The green OD-II had a circuit similar to the TS808; however, the OD and OD-II had a more distorted circuit.

After the 9 series was discontinued, the "Master" or "L" series was produced. This series was only made in 1985, and did not have a tube screamer in the lineup.

A rare and valuable version of the tube screamer was the ST9 Super Tube Screamer, which was sold only in Europe and Australia.

The TS9 and TS808 pedals have been reissued, and according to the company, feature the same circuitry, electronics and design components that helped shape the famous Tube Screamer sound. Some musicians have a technician perform modifications to the unit to change the sound to their liking. Also, Maxon, who produced the original Tube Screamer pedals for the Ibanez brand in the 1970's - 1980's, produce their own version of the Tube Screamer (called Overdrives: the OD-808 and OD-9 as oppose to Tube Screamer, TS).

According to Susumu Tamura (田村進^?) of Maxon, the designer of the Tube Screamer, the initial design concept was to create something to compete with BOSS OD-1 and MXR Distortion+. In doing so, he used an innovative circuit, using the monolithic operational amplifier device, introduced in early 70s, to create a pedal sound different from the "discrete" transistorized 60's fuzzes.

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Wikipedia