The Tone Bender MKII was a three-transistor fuzz circuit that was introduced by Sola Sound in 1966. The circuit closely resembles the earlier two-transistor Tone Bender, but the MKII has an extra gain stage in front. Sola Sound manufactured the Tone Bender MKII circuit for a number of different companies, as the OEM, during the period of 1966 to 1968.

In the interest of clarity, this page focuses specifically on the pedal that was formally branded as the ‘Sola Sound Tone Bender Professional MKII’, as pictured, that was briefly sold in late-1966. 

1966 Sola Sound Tone Bender Professional MKII
1966 Sola Sound Tone Bender Professional MKII

Based on the date codes of surviving Sola Sound-branded Professional MKII’s (and of other closely related Sola Sound fuzz boxes), and also based on the timing of references in the press to the MKII, Sola Sound’s famous model was most likely developed at some point around mid-to-late 1966. The parts selection of surviving Tone Benders from 1966 suggests that the ‘MK1.5’ was discontinued around the same time that the earliest MKII’s were being built.

1966 Sola Sound Tone Bender Professional MKII

In fact, close inspection of some Sola Sound-branded MKII’s reveals that the builder(s) actually modified existing ‘MK1.5’ Tone Benders to the new specifications, and the graphics of the enclosures were subsequently updated with the details between the footswitch & the controls, denoting the new model.

Other Sola Sound-branded MKII’s were built from scratch, and featured the same circuit layout & parts selection that Sola Sound were already using for the MKII’s they were building for Marshall, Rotosound & Dallas.

The gradual change in the mixture of electronic components in original Tone Bender MKII’s reveals that Sola Sound likely stopped using their own company’s name on the pedal’s branding by approximately late-1966/early-1967, and alongside the existing OEM supply chains, began producing the MKII as the Vox Tone Bender Professional MKII. The Sola Sound name would not appear, printed, on a Tone Bender again until approximately 1969.

1966 Sola Sound Tone Bender Professional MKII
1966 Sola Sound Tone Bender Professional MKII
After Sola Sound had presumably run out of ‘MK1.5’ stock to work on, the Tone Bender MKII’s branded with their company name were built from scratch on a larger piece of veroboard, and were identical to the version of the MKII that was being built & supplied to Marshall, Rotosound & Dallas at the same time. (Photo credit: S. Park)

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