Dating a ibanez ts808
When the output exceeds the forward volt drop of the diodes the amplifier gain is much lower, effectively limiting the output to and - one diode volt-drop, although due to the exponential I-V curve of the diodes this is not a hard limit.
A "drive" potentiomenter in the feedback path provides variable gain.
Much has been made of the operational amplifier chips used in the various versions of the Tube Screamer pedal, and several "fairy tales" about the merits of these devices have been written on the subject.
Phish guitarist Trey Anastasio implements two TS9 Tube Screamers in his rig.
The original 4558 based circuit uses transistor buffers at both the input and the output, to improve impedance matching.
This is mathematically equivalent to mixing the input signal with a clipped version of itself, however.
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–1980s, produce their own version of the Tube Screamer (called Overdrives: the OD-808 and OD-9 as opposed to Tube Screamer, TS).