Fender Blender

This article refers to the "4 knob" original Fender Blender. The information also relates the reissued effect. See my other article on the rare "3 knob" version.

4 Knob Blender

The Fender Blender appears to have landed in either 1968 or 1969.

The circuit is the earliest example I have seen of its type of octave up topology. The octave stage consists of a transistor splitter followed by diode rectifiers which are recombined for a full wave rectification effect.

This is similar to the 1967 Roger Mayer Octavia, except that the fragile and expensive transformer has been replaced by a transistor. When Roger Mayer did his first wide release of the Octavia in the late '70s, the transformer replaced with a transistor, like the Blender design.

Similarities to other designs

The Blender may or may not have also found inspiration from the Superfuzz. The Superfuzz was available as early as 1967 in the form of the Honey Baby Crying and other Fumio Mieda designed fuzzes. These pedals shipped with the schematic pasted right inside the chassis. The Superfuzz topology uses transistors as the rectifying elements (instead of regular diodes), but the transistor splitter, diode clipping stage, and switchable tone control are all very similar (Blender has a footswitch tone, Superfuzz has a slide switch tone).

The Ampeg Scrambler began its very short run in 1969. The "Blend" function is shared between the two. I like to think that the "Scrambler" name was an industry inside joke to answer Fender's "Blender" name. The Scrambler's odd circuit appears to have begun as transformerless ring modulator, but then ditched half the ring.

About 1971 the Foxx Tone Machine appeared. This pedal is very similar to the Blender, except the tone switch has been replaced with an octave switch. The octave switch is pretty clever and thus the Tone Machine distinguishes itself apart from the Blender. The Tone Machine also ditched the Blend control. The Tone Machine's overall circuit is quite similar to the Blender, but different enough to suggest that it is an original design.

In 1973, Dan Armstrong starting working with designer George Merriman on a Scrambler work-a-like. Dan had a Scrambler from his Ampeg days, and although the circuit was potted, George said he knew how to make a better one. The new device, dubbed the, Green Ringer, kicked off a new line of Dan Armstrong plug in effects. I mention it here, because Merriman's circuit is actually more like a Blender than the Scrambler. Although, this is speculation, as the London era boxes are epoxied and I haven't seen a verified schematic. The Musictronics (1976-78) versions include a MSD6150 dual diode in photos I have seen. Schematics of those have the topology of the Blender.

3 Knob Blender

Sometime in the mid or late '70s the Blender got radically redesigned into a completely different pedal. The whole Blend idea was deleted, so the name wasn't even appropriate. The '3 knob' Blender has a transistor fuzz circuit, no octave up, and a separate FET booster stage. There are actually just two rotary variable controls, one for fuzz gain, one for master volume, and the third knob is a selector switch to choose either a clean FET boost or fuzz with 3 different preset filters (4 position rotary switch).