Unit Delay - What is it good for?
  • For the life of me I can't understand what the unit delay is for - "Like the FeedbackDelay node, the UnitDelay can be used to determine where a delay occurs in a feedback loop." I've seen it has something to do with FM synthesis, correct? Any help understanding the UnitDelay or FeedbackDelay would be helpful. I think I get that the "unit" is 1 sample length, correct? Like 1/44100th of a second? Maybe someone can point me to some designs that are already posted so I can see it in action?

  • +1

    Anyone figure this out yet?
  • @Lid555 you can make dsp filters with unit delay. You can also use it for audio rate feedback and have smoother sounding results because it happens at the sample rate not the Scan rate.
  • lol yes - when you @lidd555 use something with a feedback configuration - output fed back to an input - if you do not use a unit delay, there is a pause of ~300 samples between each processing cycle. When you use a unit delay inside the feedback loop, it will force that portion to run in single sample mode, and will delay the information by 1 sample. This is helpful not just for filters as @robertsyrett pointed out, it’s also helpful for creating utilities that detect motion from sample to sample, like the up down detector, which compares the previous sample against the current sample to detect whether the current sample is higher or lower than the previous. If you didn’t use the unit delay, the up/down detector wouldn’t work properly since it would only be comparing every ~300th sample to one another.

    You can use it in any design where you want the changes to happen quickly from sample to sample. Most cases using frame rate feedback is fine. I’ll upload an example patch that will make it audibly clear what the difference is later today when my power comes back on!

    Does that make sense?
  • Thanks for the info @biminiroad and @RobertSyrett. Not to assume I understand all the details, but I think I have a good general idea now, thanks again!