Review: Meris Hedra

Review of: Meris Hedra

Reviewed by:
On June 10, 2019
Last modified:June 10, 2019



Meris has been on an awe inspiring winning streak since their breakthrough debut in the pedal world only two short years ago. They released a quick series of hits with the Ottobit Jr., Mercury7, and Polymoon, leading to an accolade for being crowned the Best New Pedal Builder of 2017. And as if that trio of stunners wasn’t enough, Meris followed up with the Enzo, a multi-voice guitar synthesizer that was widely regarded as one of the best pedals released in 2018. Now they’ve released the Hedra, a “3-Voice Rhythmic Pitch Shifter” that is arguably the most ambitious and advanced pedal concept the SoCal based builder has bestowed upon the world so far.

Hedra draws some obvious comparisons to certain pieces of harmonizing rack equipment, most notably the classic H3000 Harmonizer from Eventide. And I could easily list off a half dozen or so notable pedals released over the years that showcase commendable attempts at harmonizing and pitch-shifting that were impressive at the time when those products were originally released, pedals that are now eclipsed by the realms of possibility offered by Hedra.

As a long time fan of pitch-shifting pedals, I’ve developed very high standards for certain things I expect to see in a quality modern pitch-shifter. I’ll cover those things as we go, but it’s also important to emphasize that Hedra is a unique pedal in its own right that should also be approached with a fresh perspective. If you’ve never really played a pitch-shifter before, you’ll be at the forefront of new frontiers when you plug into Hedra. But even musicians with experience using pitch effects will benefit from approaching Hedra with the child-like wonder of discovering something new for the first time.



Rhythm & Harmony

Hedra’s surface presentation focuses on its rhythmic pitch-shifting abilities. The pedal has a dedicated Tap foot-switch that lets you tap in a delay time, setting the foundational rhythm for the pedal’s sequence of delayed Pitch voices. The 3 dedicated Pitch knobs are your means for selecting different pitch intervals for your delayed voicings. Pressing the Alt button while turning any of these 3 knobs lets you select a voice’s respective delay Time Division. This is a fairly easy and effective arrangement for quickly producing a sequence of up to 4 voices (including your dry instrument voicing).

You can choose any of 12 keys for intelligent harmonies or set the Key to Chromatic for static harmonies. There are also 7 Scale settings available as an “Alt” parameter behind the Key knob. You can choose from Major, Minor, Melodic Minor, Harmonic Minor, Double Harmonic, Lydian Pentatonic, and Minor Pentatonic. And of course you can also access any of the other 5 modes of the major scale besides the Ionian (major) and Aeolian (minor) modes depending on which Key you select; the same goes for accessing the Major Pentatonic scale by using the Minor Pentatonic scale with a Key setting 3 semitones below the actual key you’re playing in. If you already have Music Theory 101 knowledge of scales and intervals, you’ll intuitively see many ways to stretch beyond the options that are presented. But Hedra is easy enough to use that even if you have limited knowledge of scales and modes, you can just set the Key to the root note you’re playing in and select a basic Minor or Major scale and still be able to find all kinds of cool harmonized sounds by just noodling around on the fretboard while sticking to playing notes that sound good to your ears. Music theory novices will likely learn a thing or two along the way.


Classic Chromatic Harmonizing

The Chromatic Key option gets special mention as it gives you several options for dialing in classic non-intelligent harmonized effects heard over the years.

Here’s how to dial in 3 classic harmonized sounds from 3 notable songs using Hedra with the Key knob set to Chromatic:


Steve Vai – Ballerina 12/24

Dial in Pitch 1 to a major sixth (+9 semitones) at just between the 5 & 7 on the dial. Set Pitch 2 to a fourth (+5 semitones) in between the 3 & 4 setting. Set Pitch 1 to a ¼ note Time Division and Pitch 2 to a ½ note. (Leave Pitch 3 set to Off.) Set the Mix to 3 o’clock, and tap in a tempo a little over 100bpm. There you go! You’ll notice that Hedra responds surprisingly well when playing sections of this song that have multiple notes ringing out, rivaling the tracking of the original gear the song was created with. (I’ll discuss Hedra’s polyphonic abilities in detail in a moment.)

Rage Against the Machine – Know Your Enemy (intro & solo)

To achieve a comparable version of Tom Morello’s pitch-shifted guitar sound from this RATM classic, use only the Pitch 1 voice set to a perfect 5th (+7 semitones) which is easy to dial in by setting the knob to point to 5. Use the Pitch 1 knob’s Alt function to set the Time Division to minimum. Keep the Mix around 3 o’clock. You now have a harmonized 5th that has incredibly low latency, resounding instantaneously with your dry guitar signal.

Steve Vai – The Animal (main riff)

Here’s how to achieve another classic Steve Vai sound from Passion and Warfare. If you take the Know Your Enemy setting from above and drop Pitch 1 down to a -5th below (-7 semitones), you can get a super heavy sound from single notes that’ll let you pull off a great interpretation of Steve Vai’s main riff from The Animal. I’ve read conflicting reports about how Steve originally achieved the sound. Some say he recorded a 7 string guitar separately to get the -5th layer. Hedra, however, can easily add this harmony while being incredibly responsive to all the nuances of guitar playing, including vibrato and pinch harmonics. And speaking of that, let’s talk more about Hedra’s subtle capabilities…


Immediacy & Responsiveness

There are a few areas where pitch-shifters are typically judged when it comes to how well they produce harmonies and/or change the pitch of a guitar signal. General tracking and latency are common concerns, and how well a pitch-shifter responds to monophonic and polyphonic source material is another. Let’s break down each of these aspects.

The flagship concept of the Hedra is its rhythmic pitch-shifting possibilities, so delaying the 3 Pitch voices is what you’ll probably mostly be experimenting with. But if you set the Time Division of your Pitch voice(s) to minimum, you’ll achieve the least possible delay for near instant harmonies that can be heard alongside your dry guitar. This lets you create 2 to 4 part harmonies (“guitarmonies” anyone?) in any key, a commendable feat that surpasses any other pitch-shifter pedal used for similar purposes. And if you crank the Mix so that only your wet signal is heard, you can use a single Pitch voice to change the tuning of your guitar. I can confidently report that latency is a non-issue for harmonizing purposes and that Hedra is on par with the best in class for low-latency pitch-shifting.

The low-latency performance of Hedra goes hand-in-hand with its outstanding tracking. After all, the pedal will have to track exceptionally well to achieve a near-zero latency response. But Hedra also seems to surpass its peers in terms of how well it can track the nuances of guitar playing. For example, if you set Key to Chromatic, use one Pitch voice to re-tune your guitar, and crank the Mix to fully wet, you can hit a note and apply vibrato to hear how incredibly well Hedra tracks every subtle movement of your fretting hand. Then try applying vibrato when using all 3 voices with your dry signal and have your mind blown all over again at how well it responds. And if you kick on some distortion and hit a ripping pinch harmonic, you’ll be shocked yet again that it can re-pitch your guitar when you’re “poppin’ squealies”, something I’ve never heard any other pitch-shifter pedal do well at all.

Now when using up to 3 additional harmonies, it’ll usually make the most sense to play mostly monophonic melodies so that all the blooming harmonies will retain a more pleasant chordal voicing based on the root note, but Hedra can still track some polyphonic playing pretty well. If you stick to playing intervals like octaves, 4ths, 5ths, and maybe 9ths, you can usually get away with letting a few notes ring out without making Hedra’s tracking get jittery. A good example of this is trying the Ballerina 12/24 setting I mentioned above to hear how well Hedra can track when either 5ths or 9ths are ringing out. It’s very impressive. Yes, if you let 3rds and other intervals ring out with your root note, things can get jittery, but this is common with pitch-shifters. Luckily, Hedra’s “intelligent” harmonizing will let you generate those less easily tracked intervals from single notes. And this is where having 4 total voices and many ways to use them (either in unison with your dry notes or delayed) comes in handy.


Come Correct

It should be apparent by now that Hedra’s intelligent pitch-shifting is extremely powerful, letting you create cascading flurries of notes from single note melodies that retain the tonal signature of whatever Key and Scale you’re playing in. But let’s talk more about the precision with which Hedra accomplishes this as it relates to a unique aspect of the pedal.

The Pitch Correction Alt option behind the Micro Tune knob lets you lock in the harmonized pitches either loosely or tightly. This aspect is primarily for deciding how the pedal will respond when you bend notes, apply vibrato, or if your guitar drifts slightly out of tune. You can have the pedal add harmonies in relation to the actual pitch you’re playing, meaning you can bend notes and have Hedra’s Pitch voices also be offset in pitch, or you can have the voices rigidly lock in tune for precise harmonization. If you bend notes with Strict Correction, you’ll hear them audibly jump to the next pitch when your bent string pitch crosses the mid-point threshold towards the next semitone. All 3 Pitch Correction options are worth exploring depending on what a situation calls for, letting you adapt the pedal’s response to your playing style. For fun, trying setting it to Strict Correction, crank the Mix to fully wet, and use one Pitch voice with any Key and Scale; play a solo using any random notes and marvel at how every note you hit sounds perfectly in key. It’s like Auto-Tune for guitar.

Aside from the Pitch Correction options, there’s also a Pitch Glide function that will let your Pitch voices “glide” to their harmonized pitch. This can be used to create wild pitch risers and smooth legato like sounds. It’s also cool for experimental sounds and cinematic textures.



The dedicated Micro Tune knob detunes all three voices simultaneously. You can use this to achieve some excellent studio style detuning effects by setting one or more of the Pitch knobs to the root interval with minimal Time Division and increasing the Micro Tune to around 9 o’clock. It sounds comparable to sounds associated with chorus modulation only without the modulation of pitch from an LFO. It’s a unique and sought after widening effect that few pedals really execute well. The detuning can also get pretty warbly if you crank up the Micro Tune knob, a fun take on vibrato-like “seasick” sounds. But the more subtle settings are what most users will gravitate towards for adding a slightly more lush quality to the overall sound. And I almost didn’t think about this until watching Meris’ own product vid again, but the detuning can be used with the onboard delays for a pleasing delay sound that recalls modulated style delay effects. And speaking of delays…


Delay Surrealism

Hedra has several options for delaying your Pitch voices, and these aspects shine when you want to showcase Hedra as the primary effect in your chain when the pedal is activated. The Series Delay option adds a straight-forward delay with up to 520mS of delay time. The Series Delay + Pitch Feedback mode is the most extreme setting, cycling your pitched signal back into the audio path to be re-pitched again and again. Think spiraling fractal insanity; it can get pretty intense. Dual Delay mode has up to 260mS of delay time and creates a full stereo spread with the Pitch 1, Pitch 2, and Pitch 3 voices panned hard left, center, and hard right, respectively. The Dual Delay + Cross Feedback mode sends the left and right delays across the stereo field for an even more multi-dimensional delay sound. Simply describing these options doesn’t do justice to the extra versatility they offer, and I highly recommend exploring these aspects to really experience Hedra’s potential. Also, be sure to consult the manual signal flow diagrams to help wrap your head around visualizing how the delay options impact your sound.


External Pitch Control

Like Meris’ other pedals, Hedra supports control of its various parameters and options via MIDI. But there’s another mind-bending surprise inside this pedal. Hedra responds to MIDI Note On & Off messages, meaning you can essentially play your guitar with a keyboard or by sending Hedra sequences of MIDI notes from a DAW or sequencer. My first test was to send Hedra a MIDI file of a Bach harpsichord concerto. I was shocked that I could feed a single sustaining synth note from the Meris Enzo into Hedra and generate 3 voices (with the Mix fully wet) to play the major themes of the concerto note for note. Then I got more ambitious and played a single note rendition of Led Zeppelin’s Kashmir on guitar with Hedra providing an additional 3 voices to create 4-part harmonies. There are some wild options here. You could have your live keyboardist take over your guitar or maybe automate sequences of background melodies and harmonies to accompany your played guitar parts.


Triple Whammy

Before we wrap up… I never mentioned “Whammy” style effects, but Hedra can do those, too. Just use an expression pedal or the MIDI expression option and shift the pitch from any selected interval to any other. It’s ideal to use one Pitch voice with the Mix fully wet. This will allow you to get those classic +1 or +2 octave pitch bends. Use the Pitch Smoothing option for a gliding pitch-shift. With Pitch Smoothing turned off you can step through intervals to achieve an immediate pitch-shift to the extreme setting when you move the pedal quickly to the toe position. If you move it slowly, you can step through intervals of a scale for a manual arpeggiation effect. And yes, you can can use 3 Pitch voices at once for a triple “Whammy” effect or to make your root note bloom into a chordal triad (when Mix is fully wet) or 4-note chord (with your dry signal blended in). Lots of great possibilities here.


The Ultimate Pitch-Shifter?

After spending time diving in deep with Hedra, it’s apparent that this pedal has undoubtedly raised the bar when it comes to intelligent harmonizing and pitch-shifting, representing a new paradigm in this class of effects. The pedal’s greatness is not only due to the new things it brings to the table but in how well it ties all its features together in what seems to be the most powerful self-contained pitch-shifter pedal any builder has released to date.

In trying to find something to criticize, Hedra shares two minor concerns I have with other Meris pedals: reliance on external hardware for preset selection and unlabeled Alt parameters. But since Hedra is a pro level pedal that’s ideal for musicians who have a MIDI controlled rig (or at least don’t mind making room on their pedalboard for the Meris Preset Switch), using external hardware for preset selection may be preferred anyway for users who plan to make the most of Hedra’s myriad options. And Hedra’s Alt functions are fairly easy to remember although you may have to blindly feel out some of the Time Division settings and re-check the manual to see where the Scale options are located. Also, while the output level does remain pretty consistent when pushing up the Mix, I do still wish there was at least an optional MIDI parameter to set the overall output level. Using 3 extra voices, especially root notes, can increase the overall volume level with no way to compensate for this aside from just keeping the Mix set low. Luckily, this hasn’t really hindered my enjoyment of the pedal in use. So while I still dream about expanded MIDI parameters in this and other Meris pedals, there is nothing really missing that Hedra needs to be a significantly better pedal. Hedra seems to be Meris’ most complete pedal, feature-wise, and I’d further argue that it’s Meris’ best release yet and shows that their creativity is still on the rise.




Hedra raises the bar for pitch-shifters and represents the current pinnacle of Meris’ achievements; it’s arguably the most thoughtfully engineered pedal Meris has released to date. When it comes to intelligent pitch-shifting, the huge potential of Hedra’s Key & Scale options is simply unrivaled in a compact guitar pedal. Whether playing with instantaneous or delayed harmonies, Hedra replicates the source material in different pitches with impeccable detail and clarity. The Rhythmic aspects add a lot of creative possibilities and will inspire entire song sections. The Series and Dual delay modes further add to Hedra’s standing as an unmatched pitch-shifting muse. And Hedra’s ability to respond to MIDI Note messages opens up some creative potential never before seen in a pedal. For traditional and contemporary pitch-shifting that is on the cutting edge of innovation, Hedra gets my highest possible recommendation.

That concludes our Meris Hedra review. Thanks for reading.

Visit Meris for more info about Hedra.


  1. As well as offering even more nuanced tweakability by plugging in an expression pedal, the Hedra can also be used to control MIDI keyboards in real time and, for those who care, the Hedra sounds absolutely fat when paired with a synthesiser for mono-synth lines that really matter. I’ve honestly never been so flummoxed by an effects pedal, and while I can’t picture it on many pedalboards in the gigging circuit anytime soon, it’s certainly worth spending some time with. If the Hedra is a mere glimpse of what’s to come, I’m so eager to see what else Meris churns out in the years to come.


Please enter your comment!
Please enter your name here