Key Click

Key Click

_Excerpted from the OriginalHammondLeslieFaq._

The sound produced by early HammondOrgans differed from pipe organs in one characteristic way. There was an attack transient that sounded like a click or pop when a key was pressed. This was considered a defect and was caused by the audio signal being routed directly through the key contacts. As a key was depressed, the nine contacts under the key closed against their respective busbars at slightly different times and bounced as they closed. The sine waves from the constantly running generators would be connected at random points in their oscillation.

Considerable design efforts were made to reduce it but it could never be eliminated. In the patent, key click was to be removed by a bypass. In later console organs like the B3, the higher harmonics were pre-emphasized and the preamp designed with an upper frequency roll-off to help conceal the click.

Later rock and blues players found the key click characteristic to be desireable and some jazz organists consider it to be essential. Many Hammond organ simulators include a key click control to reproduce this characteristic.

For a detailed analysis of key click and the interaction of the key contacts on busbars see: https://asa.scitation.org/doi/pdf/10.1121/1.5003796