The Eventide 4000 series Ultra-Harmonizers are multipurpose programmable digital audio signal processors with pitch change capability. They are considered by some to be the greatest in a line of pitch changing special effects units stretching back to before most audio manufacturers ever heard of digital.
The 4000s are capable of creating effects you’ve never heard before, with a built-in patch editor to let you create your own effects algorithms.
DSP4500 
GTR4000
Features
The different Harmonizers in the 4000 series are optimized for different marketplaces.
Models included:
- DSP4000
- DSP4000B
- DSP4500
- GTR4000
Artists Using DSP4000
David Bottrill
Tool, Smashing Pumpkins, Muse, King Crimson
Laurie Spiegel
Matt Lange
Documentation
