PT2399 (Digital Delay Echo Audio Processor)

The PT2399 is an age old Echo Processor IC from a manufacturer called Princeton. The IC has been extensively used in audio application to create digital delays and other modulations. It can commonly be found in Karaoke mixers and other toys requiring audio modulations. A sample application circuit for the IC is show below from the datasheet.

The IC is originally from Taiwan (China) and hence most of the passive components (mainly capacitors) used in the application circuit will not available globally. But since the values are not operation sensitive you can try using a close value as possible. The IC works with CMOS technology and claims to have a very low distortion value of less than 0.5%. But still many designers have reported a mild fizzing noise during operation. Irrespective of the drawbacks the IC is still widely used in audio consoles for echo purposes. More details can be found at the datasheet linked at the bottom of this page.