Octave Up Fuzz Topologies
Transformer to Diode Frequency Doubler Fuzz
Push-Push Amp Frequency Doubler Fuzz
BJT to Diode Frequency Doubler Fuzz
A Brief History of the Octave Up Fuzz Effect
Purple Haze (1967)
In early 1967, Roger Mayer was helping Jimi Hendrix develop new sounds for his new musical project. In February 1967, Roger ran Jimi's guitar through a frequency doubling device he had built, and this sound was used for the solo in Purple Haze. Only Jimi's second single, Purple Haze's March 1967 release forever changed the pop music landscape. The solo was notably otherworldly and sounded like no other guitar tone previously heard.
A new guitar effect is born from a know electronic concept
For achieving an incredible feat like introducing a new tone to the musical vocabulary, Roger does face a lot of scrutiny on the internet as to whether he really invented the effect or not. Frequency doubling of a fixed waveform (like a sine wave) was a known and extremely common electronic principle. The basic electronic effect is observed when rectifying ac main voltage, usually 50 or 60Hz, into a steady dc voltage for a power supply. The rectified voltage's frequency doubles to 100 or 120Hz. The same idea was used for radio frequency manipulations. Old textbooks label these circuits "frequency doublers." Roger Mayer absolutely did not invent the "frequency doubling" electronic circuit, but he did deliver a frequency doubling device for guitar to Jimi Hendrix, which is a great achievement.
What is also certain is that no prior octave up guitar device has been presented so far, and an avalanche of imitators would soon follow in Roger and Jimi's footsteps.
Although I've yet to research it, I would not be surprised if some earlier electronic musicians had experimented with frequency doubling in the electronic music labs of the early 20th century. I would curious if Roger was aware of that sort of thing or not.
The first wave of Octave Up effects - Discrete Circuits (circa 1967-1973)
I have tried to figure out when each early octave up effect was released, but such information is very difficult to sort out decades later.
My top contender for the first imitation of the "Hendrix sound" is the Honey Baby Crying, released in mid or late 1967, which would become much more widely known as the Univox Superfuzz, a product of Shin-Ei electronics, and designed by legendary musical electronic engineer Fumio Mieda (Univibe, Mini Korg, Korg MS-20, etc). Fumio likely designed the circuit based on just hearing the new tones of music as he was far away in Japan and I've never heard a story of him traveling or encountering an actual Octavia in any way. He also designed a Leslie rotating speaker simulator based in the form of a phase shifter. Jimi would immortalize this effect widely know by its Univox model name: Univibe. (Older names for this same product included the tongue-in-check and somewhat racist "Resley Tone," and the fuzz/vibe combo unit the "Psychedelic Machine.")
The Superfuzz circuit is notable for doing its octave up generation quite differently than the Octavia. The Superfuzz employs a BJT splitter instead of the transformer, and rectification is achieved with a pair of BJTs in a push-push amp type configuration. Diode clippers follow to tame the signal amplitude, but these do not factor into the rectification. The can be removed for a very loud octave up effect.
The Fender Blender is the next early octave up. Release date isn't clear, but it seems to be either 1968 or 1969. The Blender, like the Superfuzz, uses a BJT splitter instead of the transformer. Like the Octavia, diodes are used as retification devices. The Blender uses a tone switch similar to the Superfuzz, and diode clippers like the Superfuzz. These similarities have always made me think the Blender used the Superfuzz as a template.
The Ampeg Scrambler is said to have been released in 1969. The Scrambler's schematic shows a diode ring in what appears to be a transformerless ring modulator circuit, but also indicates that 2 of 4 diodes in the ring were removed in the final design. The 2 diode version appears to give a stronger octave effect, and the function of the diodes is similar to the Blender's rectifier.
The Scrambler's BLEND control could be a nod to the Fender unit. I like to think the name "Scrambler" is a direct answer to the model name "Blender" as a sort of manufacturer's joke between the two companies.
In 1971 the Foxx Tone Machine debuted. The overall circuit is similar to the Fender Blender, minus the clean blend feature, and adding the small but clever twist of turning the octave effect on and off via a second switch.
In 1973, Dan Armstrong, former Ampeg guitar designer, showed his Scrambler to electronics engineer George Merriman. The Scrambler was potted, but George believed he could make a similar, and improved, unit. This became the Dan Armstrong Green Ringer. The earliest devices were made in London, in a somewhat plain enclosure, later getting a fancier enclosure when made by Wareham Electronics. A third version appeared in 1976 when US manufacturing and distribution was picked up by Mutron. The Mutron units have been traced, and the effect is very similar to the Blender's octave up section. The Green Ringer used a 3 pin dual diode package which looks like a transistor, but is actually two diodes with the anodes internally connected.
A some point in the 1970s, Tycobrahe released their outright copy of the Roger Mayer Octavia, going as far as calling their product an Octavia. These have a distinct blue box and are quite collectible on their own due to celebrity endorsements (Black Sabbath, SRV, others) and being the only "Octavia" commercially available until Mayer got into the game circa 1980.
Op Amp Rectifiers (circa 1970s - ...)
Once op amps caught on in the early 1970s, frequency doubling circuits based around ICs began appearing. This is still the most modern choice outside of DSP.
Notable effects include the Electro Harmonix Micro Synthesizer, the Pearl Octave, and others to be added here.
Passive Octave Up
It should be noted that you can also get this odd effect simply by wiring up a humbucker (or any two pickup coils) in a particular configuration. I wrote an article about this in the guitar tech section. I've heard testimony from one gentleman that this was a known "thing to do" in the 1970s for an on-board Hendrix tone, but I don't know if anyone was doing this before the Octavia.
Roger's original transformer and diode based rectification scheme is actually passive. He simply drove the transformer with enough signal to push through the passive stage.