Horizontal Pitch (HP) refers to the standard width measurement of modules used in a modular synthesizer. A single HP is equal to 0.2 inches or 5.08 mm, and modules are available in multiples of this width, ranging from 2 HP to over 100 HP.
The use of a standardized width measurement for modular synth modules allows users to easily mix and match different modules from different manufacturers to create a customized synthesizer setup. Modules of different sizes can be arranged in a rack or case to create a unique layout that fits the user’s needs and preferences.
In a typical Eurorack setup, modules are mounted in a vertical orientation, with each module having a certain number of HP. A single-row Eurorack case typically holds between 60 and 104 HP, while larger cases can hold multiple rows of modules.
Horizontal pitch is an important consideration when building a modular synthesizer setup, as the number and size of modules can affect the ergonomics and functionality of the system. A larger number of modules and a more compact layout can make it easier to navigate the system and access different controls, while a more spread-out layout can allow for more comfortable access to larger modules.