SubDecay OctaSynth octaver pedal

Octaver, Pitch Shifter and Harmonizer Basics

People new to the subject often get confused when it comes to octavers and pitch shifters. So, let’s have a look at what is what, which devices are on the market, and what they can be used for.

Table of Contents

tl; dr

Pitch is naturally related to speed. Spin a record faster, and the music will become both faster and higher in pitch. Altering the speed of tape machines while recording was an early method to achieve pitch effects. But it couldn’t be used live on stage.

Enter pitch shift technology: Creating octaves up or down can be easily done with analog technology. An octave up/down physically means exactly doubling/halving frequency, which was used in music since the 1960s. However, analog octavers are not good with polyphonic input, like chords; they work well with single note lines, generating monophonic output from them.

Digital pitch shifters (marketed as “Harmonizers” by Eventide) came up mid 1970s. Early digital technology could pitch-shift polyphonic input at lower intervals, but would sound very messy at an octave up/down. Newer algorithms, like the EHX POG’s (introduced in 2005), do polyphonic octaves well.

Guitar players often want octavers to substitute a bass player. This works well when playing single notes, but not with chords. Creating a monophonic bass line from polyphonic input is a job neither a monophonic nor a polyphonic octaver can do. You would need an algorithm that can detect and isolate the lowest note played, and octave it down. Not available as a effect pedal yet. There are pedals that get close, like the Boss OC-3 which has a mode only processing notes below a defined cutoff frequency. Boss calls this “true polyphonic octave”, which is plainly wrong ... it’s more “mono from poly”. 

A Brief History of Pitch

Pitch and speed are physically the same; both means frequency of events in time. Our ear hears slow periodical cycles as a rhythms, and faster ones as notes. The physical unit for pitch is Hertz (Hz), defined as a cycle per second. The musical unit for speed is BPM, defined as one beat (cycle) per minute. So, 1 Hz is basically the same as 60 BPM. Somewhere around 20 Hz / 1200 BPM, our ear switches from hearing a rhythm to hearing a low note.

In the pre-digital age, there were mainly two ways to alter the pitch of a signal: You could make audio (like, a vinyl record or a tape) faster/slower to pitch it up/down. And you could use quite simple analog circuitry to create octaves above or below the original signal. Both were already used in the 1960s. Like, Jimi Hendrix used both an Octavio (analog pedal) and half speed recording on “Purple Haze” to create octave-up effects. 

Both technologies had their shortcomings:

  • Analog octavers could only do octaves, no other intervals. And they would only work monophonic, that is, on single note melodies. Octaving chords would result in strange noises, sounding a bit like ring modulation.
  • By altering tape speed, you can make audio constantly faster and higher, or slower and lower ... but this only works in the studio. Well, of course you can change the speed of a tape delay or analog delay to get glitching effects. Or, with a very short delay time, changing it periodically will give you pitch vibrato. But you cannot generate, say, a constant minor third below your signal on stage this way.

This is where digital pitch shifting comes in: In 1975, Eventide released the H910, the first commercially available digital pitch shifter. In the following decades, digital pitch shifting was further developed, stuff like intelligent pitch shifting, Whammy pedals, Autotune and fully polyphonic pitch shifting would follow.

What is what?

Pitch shifter: Basically, all effects that constantly alter the pitch of an audio signal can be called “pitch shifters“; including analog octavers. But most of the time, “pitch shifter” will mean a digital device/algorithm.

“Intelligent” pitch shifter: A digital device or algorithm that can detect the pitch of the notes that you put in, and can create suitable harmonies. While there is already software like Melodyne that can recognize the pitch of polyphonic material like chords, all current guitar effect units that I know of can only detect the pitch of single note lines. On the device, you typically define a scale (like “A major”) and make settings what interval to add (like, “3rd up” or “6th down”). 

Harmonizer: “Harmonizer” is a registered trademark by the company Eventide. So, basically it’s just a copyright-protected name for a pitch shifter. Though, many people use it specifically when speaking about intelligent pitch shifters.

Octaver: A pitch shifter that only does octave intervals. Often used to refer to analog octavers. But there’s also an increasing variety of digital octavers, which, in contrast to the analog ones, can also do polyphonic octaving. 

Monophonic vs. Polyphonic Octavers

As mentioned above, analog octavers are monophonic in the sense that they can only create an octave up, or down, based on single note input. Chords will confuse them. Also, they will always alter the signal, especially analog octave up will inevitably create some fuzziness. Early digital pitch shifters had similar problems: The larger the pitch shift interval, the glitchier the results of polyphonic input would be. A typical example is the original Digitech Whammy I Pedal from 1989: Play chords in a one-octave-up setting, and you will get a big glitch-o-rama. Which can have its own charme: Radiohead famously used this glitchiness to create the broken-computerish sound of the “My Iron Lung” riff.

Newer algorithms however can perform clean polyphonic shifting of +/- 2 octaves; brought to the masses by EHX with their POG (polyphonic octave generator) in 2005. 

Here’s where confusion often comes in: Guitar players, especially acoustic players, want to use octavers to simulate a bass player. Like, on most larger modern keyboards, you can create piano sounds where only the lowest note you play will be doubled with a bass sound one octave below that note. Unfortunately, this is not so easy on guitar. Question: Do I need a monophonic or a polyphonic octaver to get me there? Answer: Well ... neither.

A polyphonic octaver will create a slightly digital sounding, but otherwise correct one-octave-down transposition of whatever chords you will play. The problem? Chords played really low tend to sound very boomy/mushy ... that’s why the vast majority of bass parts in most musical styles are monophonic, that is: single note lines. (Of course there’s exceptions, like Tony Levin’s beautiful bassline on Peter Gabriel’s “Don’t give up”). A monophonic octaver will neither get the job done, since polyphonic input will confuse it.

So, what you would actually need to fake a bass player is an algorithm that detects the lowest note you play, and adds an octave to only that note. Advanced pitch modification software like Melodyne may be able to do stuff like this, but I don’t know of any effect pedal that can. There’s a few reasonable approaches, though:

  • The Boss OC-3 has a mode where a low pass filter is used: Only notes below the filter frequency will be sent to the octaver section. Confusingly, they call this “World’s first compact pedal with true polyphonic octave effects” – which would be a accurate description of the EHX POG, while the OC-3 “Poly” mode actually is “clever monophonic”. Downside: For this to work, you need to define a certain “split note”, and play only monophonic stuff below that note. This can work fine with picking guitar, but rather not with strumming.
  • There’s the Submarine Pickup that only picks up sound from the two lowest guitar strings. Put this through any octaver, and you will get a similar result like with the OC-3, but more reliable: Only the two lowest strings will be octaved. Still, not suitable for strumming chords accross all 6 strings.
  • The best current solution are hexaphonic pickups: There, you get an individual output for each guitar string. Old Roland guitar synthesizers use this technology, and I think also Line6 Variax guitars. However, there is one dedicated solution that combines a hexaphonic pickup with an analog octaver that only affects the lowest note played; for me, this is the best implementation of the “fake bass player” idea: 

What is it good for?

There’s two basic ways of using pitch effects: One is to fake stuff (like bass players or 12-string guitars), e. g. to make live performing more convenient. The other is to create sounds that otherwise would not be possible. So, here’s some applications of pitch effects, and devices you can use for them.

Monophonic Octave Up

Following the original Octavio used by Jimi Hendrix, there’s a ton of analog Octave Up pedals out there, mostly combining octaver with fuzz. It’s a very specific sound, mostly suitable for lead lines played quite high up the fretboard, like 10th fret and above, and works best with neck pickup. Here’s a small selection of current production pedals:

  • The EHX Octavix is a standard Octavia implementation with an additional switch to internally step up voltage from 9V to 24V for a tighter sound, at a quite low price.
  • The JDM Humdinger allows seperate footswitching of silicon fuzz and octave circuit and comes at a reasonable price.
  • The Bigfoot Octo Puss offers only the octave up without the fuzz. The interesting part: It’s fully passive, no power supply or battery needed.

There’s many many more, from EQD Tentacle and Hoof Reaper to Foxrox Captain Coconut and Octron to Dunlop who owns the Octavio brand today. Also, many digital modelers emulate the octavia; on Line6 devices like M5/M9/M13, look for “Octave Fuzz” to get a rough idea how an Octavio could sound.

Monophonic Octave(s) Down

We already mentioned the Boss OC-3 above; its predecessor OC-2 was one of several octavers producing clean one or two octaves down, that are popular with bass players; such as the EBS Octabass or the Ampeg Sub Blaster (currently not in production). Pino Palladino famously used the OC-2 while working with Paul Young in the 1980s, also Tony Levin on Peter Gabriel’s “Sledgehammer” used an Octaver on his bass.

There’s also analog devices that make the lower octaves sound more synth-ish, like the Subdecay Octasynth pictured above. The EQD Bit Commander takes the concept a step further, combines rather distorted analog octaves down and up for some wild sounds that sometimes can sound like Jon Lord playing monophonic licks on a heavily distorted Hammond organ.

Nowadays, many guitar players use digital octavers for monophonic octave down effects. Famous examples include The White Stripes’ “Seven Nation Army” where a Whammy provides the bass sound, and lead sounds of Michael Krammer from the Austrian Band Bilderbuch, mixing in a lower octave from his Whammy. 

Slight Detune

A very popular use of pitch shifters in the 1980s was to create a chorus-ish effect by adding a slightly detuned signal to the dry signal; typically used in stereo, with a slightly pitched-up signal on one side and a slightly pitched-down one on the other side. It sounds basically like a chorus, just even more, well, sterile, HiFi, 1980s. Still, guitar players and studio engineers use it today; like Chris Lord-Alge when mixing Muse (  

Fixed Pitch Shifting

Formally, of course also octavers and slight detune falls in this category. Mixing in a pitch-shifted signal at an interval other than octaves can sound very strange. There is a very famous example however: The solo on “Owner of a Lonely Heart” by Yes. According to Guitar Player Magazine, Trevor Rabin used a MXR Pitch Transposer here; mixing in a fifth-up. You can get this effect with almost any digital pitch shifter on the market, starting from a cheap Line6 M5 or TC Quintessence.

Another popular use of fixed pitch shifting is to use it without the dry signal, like, to emulate a drop-tuned guitar in a live performance where you don’t want to waste time by tuning the guitar down. Dedicated devices for this application include the Digitech Whammy DT and the DropTune by the unfortunately closed-down company Morpheus FX.

Variable/“Intelligent” Pitch Shifting 

We’ve talked about intelligent pitch shifting above: This typically means that a device detects the notes (in a single-note melody), and adds intervals that you define, “intelligently” adapting to a scale you define. Many guitar players use this to be able to replicate heavy metal harmony leads alone (typically played by two guitars in a third or sixth interval). Still, for many famous harmony leads, defining one interval is not enough. To get them, you would either need a keyboard / sequencer sending the intervals to be shifted via MIDI; or you need to manually switch between different scales/intervals. 

I’ve made some vids to demonstrate how you can precisely emulate the harmonies of The Beatles’ “And your Bird can Sing”The Eagles’ “Hotel California” and Pink Floyd’s “Dogs”, using a cheapo Line6 M5 together with an expression pedal or a MIDI switcher. As you can hear, the artificial harmonies never sound as good as if two decent guitar players would actually play them together. So, this is really just a budget solution for live performances where you can’t have an additional guitar player. However, there are artistically interesting uses of MIDI-controlled harmonies on vocals, such as Imogen Heap’s great track “Hide and Seek”, or Bon Iver’s “22, A Million” album.

A special type of intelligent pitch shifting is Autotune, introduced 1996 by Antares, made famous by Cher’s 1998 hit “Believe”. This detects the pitch of incoming signals and automatically shifts it to the closest exact note of a defined scale; with a slow reaction time, it can be used to correct sloppy intonation of singers. With a fast reaction time, you get the Autotune effect that is all over today’s pop music. When Daft Punk released “One more time” in 2001, I thought “great track, but why still Autotune, isn’t this getting old?” – well, obviously people are still not bored by this effect 18 years later, you hear it everywhere on vocals. Yet, for guitar, it never became really relevant.

Pitch Glide (“Whammy”)

When Digitech introduced the Whammy I in 1989, it made a big impact: You could make crazy pitch dive effects of up to +/- 2 octaves, as famously featured by Joe Morello in his guitar solo on Rage Against the Machine’s “Killing in the Name” (1991). Also, the glitchy sound that you get when playing polyphonic material at larger intervals made it interesting at fixed pitch, as in Radiohead’s “My Iron Lung” (1994).

Fun fact: The algorithm used on the original Whammy I (and the less successful Whammy II) was created by IVL Technologies. Digitech used own algorithms starting with their Whammy III; the original Whammy I became a bit of a cult object and was sold for high prices, though the current Whammy V can emulate it quite convincingly. IVL merged into TC Helicon in 2000, a company now owned by Behringer’s Music Group. So, in theory, Behringer has access to the original Whammy I algorithm, while Digitech hasn’t. No idea whether or not they use it in pedals like their US600.

A automatic version of the Whammy-ish pitch glide effect was introduced by Boss with their PS-5 pedal; called T-Arm there, and S-Bend on the follow-up model PS-6. Here, one tap on the pedal will trigger a predefined glide up or down curve. This sound was notably used by the Black Keys on their 2011 track “Lonely Boy”. Digitech followed with their Ricochet, a dedicated Auto-Whammy pedal with more control compared to the Bosses. Also the EHX Pitch Fork can do similar effects. 

In my Line6 M5 + Boss ES-5 video, I'm showing how you can both reproduce the Boss-based “Lonely Boy” sound and the classic Whammy sound as used on “Killing in the Name” and “My Iron Lung”:

Polyphonic Octaves

The POG and HOG series pedals by Electro Harmonix have made polyphonic octaving very popular: Be it for simulating 12 string guitars and organs, or for previously unheard special effects. Also, some players use POG variants to fatten up their sound by just mixing in a tiny bit of upper and/or lower octaves. I guess it’s safe to assume that the EHX B9 and C9 organ emulation pedals are based on the same algorithms as the HOG 2/POG 2, just with preset values for the different interval levels, and maybe some additional filtering / dynamics processing.

Quite some other polyphonic octave pedals were released after the original POG by other companies; including TC’s Sub’n’Up and Mooer’s “Tender Octaver”. The latter appearantly was a direct rip-off copying the firmware from the EHX Micro Pog; according to EHX, even the EHX copyright note can be found in the copied Mooer firmware. Also, current Digitech pitch products such as Whammy V, Ricochet and The Drop as well as Eventide Pitch Factor and H9 (PitchFlex Algorithm needed), and the EHX Pitch Fork can do polyphonic octaves. EQD came up with the Organizer, which offers most of the features of the POG 2 in a smaller box – but, at least for my taste, the POG 2 sounds considerably better and does a more realistic organ emulation. Check John Mayer’s “In Repair”, organ-ish sounds there are mainly guitar through POG.

When it comes to modelers, the old Line6 devices (M5/9/13) cannot do polyphonic octaves, but the new Helix/HX models can. Zoom is trying, but for my taste not convincing.