The sound - as well as the circuit - reveals: this is more a Big Muff than a Tone Bender. This particular model, the Jumbo Tone Bender, was available in different designs throughout the years of production. My unit is a very early one from 1976, less colorfull than later versions (see the sample in the Youtube video below).
09/27/2020: ToneHome is looking for an Ibanez CS-505 narrow box first issue with flying fingers side graphic. Any hint is highly appreciated. Other than that we're looking for an Ibanez AD3000 Professional Analog Delay & Multi Flanger and an Ibanez OD-850 narrow box (v2-v5) either boxed or just the empty original box. Please submit your offers or leads here: e-mail