Ibanez Tube Screamer

Ibanez Tube Screamer TS9

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 and most copied overdrive pedals.[1]

Description

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.[2]

Variations

The pedal was produced with many variants:

The tube screamer pedal was preceded by the orange "Overdrive" and green "Overdrive-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. 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 ST-9 Super Tube Screamer, which was sold only in Europe.

The TS9 and TS-808 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 1970s and 1980s, produce their own version of the Tube Screamer.

Design

Mr. S. Tamura, the designer of the Tube Screamer, used a subtle distortion circuit to create the pedal's sound. The overdrive is produced using matched diodes in the feedback circuit of a variable-gain operational amplifier ("op-amp") circuit, to produce soft, symmetrical distortion of the input waveform. While ubiquitously referred to as "clipping", the overall effect of this stage is actually a form of crossover distortion. As the voltage passes through zero, it "jumps" up or down by a diode drop, expanding the height of the waveform in the middle. (A clipping circuit would have the signal going into the inverting input of the op-amp rather than the non-inverting input.[3])

This is mathematically equivalent to mixing the input signal with a clipped version of itself, however. Thought of this way, it is said that this "preserves the original dynamics of the input signal which otherwise would get lost at the threshold of clipping" and "avoids muddiness and vastly improves clarity and responsiveness."[3]

Characteristic of the distortion is the symmetrical nature,[4] which produces only odd-order harmonics for a sine wave input.[5]

Much has been made of the operational amplifier chips used in the various versions of the Tube Screamer pedal, and several articles have been written on the subject.[6][7] The JRC4558D chip is particularly well-regarded.[1] In fact, the JRC4558D is used in Analog Man's "Silver" modification. Other popular chips included the TL072, RC4558P, and OPA2134. The TA75558, standard in the TS10 alongside the 4558, is regarded as the "ugly duckling of TS opamps."[1]

In reality, the type of op-amp has little to do with the sound of the pedal, which is dominated by the diodes in the op-amp's feedback path.[8][9] (See Op-amp swapping.)

As well, Tamura added a post-distortion equalization circuit with a first-order high-pass shelving filter that "is linearly dependent on its gain," an approach called "progressivity."[3] The overdrive stage is followed by a simple low-pass filter and active tone control circuit and volume control.

The circuit uses transistor buffers at both the input and the output, and electronic field-effect transistor (FET) bypass switching to turn the effect on and off.

The TS7 allows switching between a "TS9" mode, in which the circuit and all relevant component values are identical to the vintage model, and a "Hot" mode, which introduces an additional gain stage. Yet another variant is the Ibanez ST9 Super Tube that features a fourth knob ("Mid Boost"), which provides a harder attack.

Notable users

The pedal was popularized by Stevie Ray Vaughan. Phish guitarist Trey Anastasio implements two TS9 Tube Screamers in his rig. It is widely used in genres as diverse as country, blues and metal. The Tube Screamer has since spawned many clones and modified versions.[10] It is also used by the majority of metal guitarists before the lead channel of the high gain amps to make distortion more focused and to cut the low end. Notable modifiers of the pedal include Robert Keeley of Keeley Electronics and Steve McKinley of Tube Screamer Mods.com.[11]

Notable Users:

References

  1. 1 2 3 Hunter, Dave (2004). Guitar effects pedals: the practical handbook. Hal Leonard. pp. 68–71. ISBN 978-0-87930-806-3.
  2. ↑ CSGuitars (2013-12-09), How Not To Dial A Metal Sound, retrieved 2016-02-07
  3. 1 2 3 Topaktas, Bogac. "Tube Screamer’s Secret". BTE Audio. Retrieved 13 September 2010.
  4. ↑ Zölzer, Udo; Xavier Amatriain (2002). DAFX: digital audio effects. John Wiley and Sons. p. 125. ISBN 978-0-471-49078-4.
  5. ↑ "Harmonic distortion". rhordijk.home.xs4all.nl. Retrieved 2016-02-07.
  6. ↑ "Ibanez Tube Screamers History". Analogman.com. Retrieved 13 September 2010.
  7. ↑ Möller, Andreas. "The "true" TS-808 chip ...". Stinkfoot Electronics. Archived from the original on 12 June 2010. Retrieved 13 September 2010.
  8. ↑ "Converting modern Tubescreamers into the real 808 version" (PDF). And do remember that the op-amp has very little to do with the actual clipping in a TS circuit. It's just there to amplify the signal - the diodes [do] the clipping. Changing one or both of the diodes will make a huge impact on the overdrive character, while the differences incurred by different op-amps are minute.
  9. ↑ "The JRC4558 Myth". electrosmash.com. Retrieved 2016-02-09. in a guitar pedal there are a lot of factors that can modify the sound even more than the opamp can do: the components placement, values tolerance, circuit layout, the power supply, etc ... by actual listening test as well as oscilloscope traces and spectrum analysis, there is no audible difference between today's 0.5$ NJM4558D and the old ones.
  10. ↑ "Ibanez Tube Screamer". musicradar.com. Retrieved 1 September 2011.
  11. ↑ Tucker, Lindsay (November 2011). "Builder Profile: Keeley Electronics' Robert Keeley". Premier Guitar. Retrieved 20 January 2012.
  12. ↑ http://www.premierguitar.com/articles/22363-rig-rundown-joan-jett-and-the-blackhearts

External links

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