Harmonizers are a type of pitch shifter that can merge the shifted pitch with the original pitch. By doing this, the player is able to create a two or more note harmonies. When used for digital recording, you achieve pitch shifting through digital signal processing. The first digital processors could pitch only in post-production, but modern units are able to modify pitch values virtually in real-time. An audience might hear extremely perfect harmonies when listening to a harmonizer, but things are never that obvious and never too perfect. Harmonizers can add special effects to instruments, just as they can detune and create weird effects out of any audio content.

Harmonizers: How They Work

In simple terms, harmonizers create harmonies, although it would be easier to create them with DAW software. It’s rather difficult to automate parameters on a hardware unit. For this reason, in order to fix individual notes, the player has to adjust the pitch knob manually. And they must do so while the mix is on. Another way of doing this is to process a copy onto a different track and mute the original track afterword.


Harmonizers can mimic the effect of doubled-track vocals, especially for faster pop tunes. Double tracking can occur with many instruments, including guitars. A hassle with double-tracking happens when the singer or player must perform exactly the same way, twice. This is because timing errors might go unnoticed on the first round, but are quite evident with two tracks playing at the same time.

In contrast, a harmonizer can create an automatic double-tracking effect from a single performance. Experts refer to this as the automatic double-tracking effect, aka ADT. ADT offers the possibility of merging the original and shifted versions. You can also pan them to center. Harmonizers can also add a full effect by panning the original and the shifted version to the opposite sides.

A harmonizer is able to raise or lower the pitch. A larger shift adds more to the effect, but it might sound out-of-tune in the long run. By using a harmonizer effect for automatic double-tracking, the player can prevent the echoing sound of the static comb filtering.

How It Used to Be and How It Is Today

The Eventide H910 Harmonizer was the first digital shifter that didn’t change the timing. When Eventide launched it, many music producers used it to give special effects to their runes. Nowadays, those who use them are usually out-of-tune singers.