The Ibanez Tube Screamer is an overdrive effect pedal produced by Ibanez which is named for the fact that its light distortion is similar to the sound given by overdriven tube amps. The pedal's sound is different from most distortion pedals as the waveform is compressed with little loss of the original signal, creating a full bluesy tone. Description The pedal has an overdrive knob, a tone knob, and a level knob. The drive knob controls the level of distortion, the tone knob adjusts the amount of treble in the sound, and the level knob controls the output volume of the pedal. The pedal can be used on a solid-state amp to try to mimic the sound of a vintage tube amp, although many guitarists prefer to use it to push a tube amp's preamp tubes into an overdriven state. The classic Tube Screamer sound includes a "mid-hump," which means that the circuit accentuates freqencies between the bass and treble ranges (mid-frequenc ies). Many 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 early incarnations of the TS-808 and TS-9 are the most sought after by collectors, due in part to the fact that Stevie Ray Vaughan is known to have used them as part of his signature sound. Other variants, including the TS-10, TS-7, and TS-5 are less collectible, but contain a nearly identical underlying circuit. The TS-9 and TS- 808 pedals have been reissued, but not all of these reissues are using the same parts (chips) that helped to shape the famous tubescreamer sound. Some musicians are having a technician perform modifications to the circuit to improve the sound. In addition, a number of other effects manufacturers make versions of the Tube Screamer circuit, including Maxon (who produced the original Tubescreamer pedals for the Ibanez brand in the seventies and early eighties). In addition, many of the most highly-regarded overdrive pedals, both mass- manufactured and boutique, owe their heritage to the Tube Screamer circuit. Because the Tube Screamer produces symmetrical clipping, its tone may be associated with a vintage characteristic. Other overdrive pedals such as the Boss SD-1 clip the waveforms asymmetrically, which has been said to result in a more tube-like overdrive. Effectively, what the Tube Screamer actually does is overload an amplifier's preamp circuit with an artificial amount of gain. When used with a cranked master-volume type tube amplifier, this can result in much higher volumes than before the pedal is engaged if the preamp is not already turned up fairly high. Provided the preamp gain is already turned up, the Tube Screamer will saturate the signal, creating a thickly overdriven tone. Design Mr. S. Tamura, the designer of the Tube Screamer, used a subtle clipping circuit to create the pedal's sound. He mixed the input signal with the output signal of the clipping circuit, which "preserves the original dynamics of the input signal which otherwise would get lost at the threshold of clipping.": In this fashion, it preserves the "...original dynamics of the input signal [and] avoids muddiness and vastly improves clarity and responsiveness." As well, Tamura added a "Post-clipping equalization circuit" with a "first-order high-pass shelving filter" that "is linearly dependent on its gain", an approach called "progressivity." The circuit uses transistor buffers at both the input and the output. The overdrive is produced using a variable gain op-amp circuit with matched diodes in the feedback circuit to produce soft, symmetrical clipping of the input waveform. The overdrive stage is followed by a simple lowpass filter and active tone control circuit and volume control. This circuit is unexceptional,
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8/7/2019 The Ibanez Tube Screamer is an overdrive effect pedal produced by Ibanez which is named for the fact that its ligh…
and the success of the Tube Screamer's sound probably has more to do with intelligent
selection of tone shaping elements (particularly capacitor values) throughout the circuit. Later
versions include a "Hot" mode, which modifies the circuit slightly to produce higher gain
sounds. The TS-7 is notable for this, since it allows switching from "Classic" (i.e., TS-808 or TS-
9-like sounds) to "Hot" mode.
Much has been made of the OpAmp (operational amplifier) chips used in the various versions
Tube Screamer pedal, AnalogMan has written a history of the tubescreamer that explains this.
The JRC4558D chip is particularly well regarded. In fact, the JRC4558D is used in Analogman's
"Silver" modification.
Trey Anastasio of Phish fame uses two silver-modified TS-9s on his pedalboard. The Tube
Screamer uses electronic FET switching. [ from Wikipedia ]
Tube Screamer®’s Secret
This work is dedicated to Mr. S. Tamura, the designer1 of the Tube Screamer®
TUBE SCREAMER® is a registered trademark of Hoshino Gakki Co. Ltd. It is used solely to
identify the product whose tones and sounds were studied during the research and discovery of the information provided in this article. This information is provided “AS IS” without warranty
of any kind, either expressed or implied, including but not limited to the implied warranties of
merchantability and/or fitness for a particular purpose. The author specifically disclaims
responsibility for any loss of profit or any consequential, incidental, or other damages resulting
from the use or misuse of the information provided in this article. VST is a trademark of
Steinberg Media Technologies GmbH.
Although the circuit design details of the legendary Tube Screamer ® overdrive pedal have been extensively analyzed and documented2 in the past, the key
aspect of its design, which is primarily responsible for the signature overdrive
sound, has remained unrevealed. This key aspect consists of a subtlety in theclipping circuit employed by the legend.
Operational Amplifier based inverting amplifiers with back-to-back
diodes in the negative feedback path are common clipping circuits which areregularly utilized in overdrive and distortion effect designs3. Figure 1 shows the
It turned out that the output waveform of the noninverting clipper consists
of two components: (1) the amplified and clipped version of the input waveform
(2) plus the unamplified input waveform. That is, the noninverting clipper adds(or mixes) the original input signal to the amplified and clipped input signal.
The amplified component is softly clipped at the forward-voltage drop of the
diodes, whereas the combined components are clipped hardly at positive andnegative supply rails in rail-to-rail operational amplifiers or at a level lower than
the positive and negative supply rails in non-rail-to-rail operational amplifiers.
Inserting a 47nF capacitor in series with the resistor R1 in Figure 3 formsa pre-clipping first-order high-pass filter with a cutoff frequency of 720.484 Hz
(R1= 4.7 KΩ). This filter causes phase shift between the unamplified input
waveform and its amplified and clipped version, which results in the output
waveform shown in Figure 5.
Figure 5. Effect of the high-pass filter’s phase shift (R1: 4k7 - R2: 51K - D1, D2: 1N914)
Mixing the input signal with the output signal of the clipper preserves theoriginal dynamics of the input signal which otherwise would get lost at the
threshold of clipping. Preserving original dynamics of the input signal avoids
muddiness and vastly improves clarity and responsiveness. This subtle feature
constitutes the heart of Tube Screamer
®
’s legendary sound and feel.Block diagram representations of Tube Screamer ®’s clipping circuit and
post-clipping equalization circuit are shown in Figure 6 and Figure 7respectively.
8/7/2019 The Ibanez Tube Screamer is an overdrive effect pedal produced by Ibanez which is named for the fact that its ligh…
Figure 6. Block diagram of Tube Screamer®’s clipping circuit
Post-clipping equalization circuit contains another subtle detail: the exact
cutoff frequency of the first-order high-pass shelving filter is linearly dependenton its gain (i.e. boost/cut gain in dB) parameter (with slightly different slopes
for boost and cut segments). This is called progressivity of the parameters 4
and it is an inherent feature of almost all great sounding analog equalizationgear.
Figure 7. Block diagram of Tube Screamer®’s post-clipping equalization circuit
In order to verify the abovementioned concepts, a VST software plug-in is
