TimeFX Echo / Delay

TfxEcho is an echo effect AudioUnit Extension plugin. It uses delay lines which are inspired by BBD (bucket brigade device). BBD is used in various analog delay unit and is known for its warm and dark sound. The delay line uses fixed length buffer and an artificial clock to sample input signal in variable sampling rate. When the delay time is changed, the delay line can produce pitch change effect which is similar to the behavior of the BBD based analog delay unit. 

The delay line is inspired by BBD, but it is not emulation of the any particular BBD. Unlike the typical BBD based delay unit, frequency range of the delay line is not limited. The delay line is capable to capture signal in higher frequency up to about 22KHz. 


TfxEcho  (AUv3)
  • Delay Time: From 20 ms to 1200 ms
  • Feedback: From 0 % to 100 %
  • Adjustable lowpass filter and high-pass filter.
  • Modulation rate: From 0.01 Hz to 10 Hz
  • Modulation width: From 0 ms to +/- 10 ms
  • Delay time can be synced to tempo provided by the host application.
Host application uses system audio input as an audio source and processed audio signal is routed to the system audio output.


Delay Time

Range from 20ms to 1200ms


Range from 0% to 100%


Range from 0% to 100%

Highpass Filter

Range from 20Hz to 500Hz

Lowpass Filter

Range from 1000Hz to 20000Hz

LFO Frequency

Range from 0.01Hz to 10Hz

LFO Intensity

Range from 0.0 to 1.0 (from 0ms to +/- 10ms)

Effect Switch


Sync Switch


Modulation Switch


Frequency Range

From 0Hz to 22.05KHz (effect)

*Appearance and specification of products are subject to change without notice.


User Guide (V1.6)

TfxEcho is available now on the Apple App Store.

Release Note

Version 1.0

  • Initial release

Version 1.1

Version 1.1 contains improvements and bug fixes.
  • Limiter is inserted in feedback loop to prevent delay lines from blowing up.

Version 1.2

Version 1.2 contains improvements and bug fixes.
  • Fixed distortion caused by large amount of feedback.
  • Fixed click noise caused by turning effect button on or off.

Version 1.3

Version 1.3 contains bug fixes.
  • Fixed a problem in initialization process of AudioUnit Extension which may leads the AudioUnit Extension to crash or may leads state recovery to fail.

Version 1.4

Version 1.4 contains improvements and bug fixes.
  • Support iOS 14 / iPadOS 14.

Version 1.5

Version 1.5 contains improvements and bug fixes.
  • Support iOS 15 / iPadOS 15.

Version 1.6

Version 1.6 contains improvements and bug fixes.
  • Support iOS 16 / iPadOS 16.