The Technology of the Tube Screamer

The Tube Screamer series of distortion/overdrive boxes from Ibanez has a reputation that has led them to pass into musical urban myth. Helped along with Stevie Ray`s use of them, the TS 808 and TS 9 have been sought after and traded up to astronomical prices. The other members of the TS family, the TS-10, the TS-5 and the TS-9 reissue have had a m
The Technology of the Tube Screamer - schematic

ore troubled reception. All the members of the TS family share a common technical design, with the similarities vastly overwhelming the differences. Later, I`ll go over some of the things that DO make differences in these pedals, and some mods to effectively convert one to the other. The TS series seems to be at its best when driving the input to a tube amplifier - that is, a triode grid connected to ground through a resistance of about 1M. All the TS series are capable of making their own distortion, but by itself, this distortion is much less interesting that what you get into a tube amp input. All of the TS series are so similar that a single schematic with asterisks and notes can cover them all. This simplified schematic breaks the circuit down into some simpler blocks. There are some housekeeping/utility stages which provide some common functions to several stages. The TS10 is the most different one, and the common bias voltage is higher. Then there are the ones that actually do the work: The 9V battery and external 9V input are common to all stages, as is the 4. 5V generation stage, used as a bias voltage by all stages. The 4. 5V section uses two equal resistors from +9V to ground. The junction of the two resistors sits at « the battery voltage and is decoupled to ground with a large value electrolytic capacitor to hold this point at an AC ground. The input jack switches the battery (-) terminal to ground in the...

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