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 below. 

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.

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 fuzz boxes were built from scratch, and featured the same circuit layout & parts selection that Sola Sound were already using for the Tone Benders they were supplying, as the OEM, to Marshall, Rotosound & Dallas.

Internals of two Sola Sound Tone Bender Professional MKII fuzz boxes

Pictured above, the pedal on the left is a fairly early Sola Sound Tone Bender Professional MKII, which originally started out as a two-transistor Tone Bender ‘MK1.5’, before having been modified at the factory to MKII specifications. The pedal on the right is a slightly younger Sola Sound-branded MKII. Built on a dedicated larger piece of stripboard, this version of the MKII has fairly typical features such as the Wima 25µF power filter capacitor, as well as the omission of the 100Ω limiting resistor. (Photo credit: J. Logan & J. Roth)

The gradual change in the mixture of electronic components in original Tone Bender MKII pedals reveals that Sola Sound significantly scaled down the use of their own company’s name on the branding of the model, following the introduction of the Vox Tone Bender Professional MKII. This may have coincided with the Macaris’ 1967 takeover of Vox’s retail outlet on 100 Charing Cross Road,1 but that has not been confirmed yet. Some of the earliest known Vox-branded Tone Bender Professional MKII’s were in fact Sola Sound-branded pedals that had the name crudely obscured.

Sola Sound did continue to manufacture the MKII under their own name, alongside the various existing OEM supply chains, but based on the rarity of late-production Sola Sound-branded Tone Bender MKII pedals, this was certainly only done in relatively small numbers.

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The Tone Bender Professional MKII, as advertised in the November 1966 issue of Beat Instrumental.
  1. Beat Instrumental, February 1967, p. 25

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