What is Audio Dither

[amirm]

Dither is a very non-intuitive concept. By adding noise, we can improve the performance of a digital system. Instead of writing a ton of text to explain it, I found this great video does it even better with animations. It is short and very good watch:

 

[amirm]

And here is one with the audible results shown:

 

[NorthSky]

Alright, the "Dither" subject.

Here's one of my CD players: http://www.audio-ideas.com/reviews/digital-sources/rotel-rcd-991.html

"Speaking of variables, compulsive fiddlers and system tweakers will either be delighted or driven to stark, drooling bouts of madness by the 991’s adjustable dither feature (The 991’s user manual defines dither as “a very small amount of digital noise added to a signal to improve a CD player’s overall sound quality [by improving] a digital-to-analog converter’s linearity, particularly during very soft (low-level) musical passages). Using a button on the front panel users can select the level of dither to be added to the signal, allowing you to match the player’s sound to your other equipment, your room, the shape of your ears, your mood, or the sound your fridge makes. In addition to a no dither setting there are seven settings which progressively add more ultrasonic (30-80Khz) weighted dither and, an eighth setting which adds low level broadband dither “not weighted towards the ultrasonic range” which is intended to correct quantization errors only. More on fiddling with power cables and dithering with dither below."

"And, as if all this coning and cabling wasn’t enough, there’s still the matter of that little dither button isn’t there. Sadly, you can’t change dither settings via the remote control, which means each change necessitates a trip out of the listening chair to the player. The differences were quite subtle, but adding dither increased the player’s ability to dig low level ambient cues out of the bitstream, the delicate decay of sounds into acoustic space best preserved at the highest dither setting. There was a tradeoff, however, a very slight drying out of the midrange with increased dither, most noticeable on female vocals. My preference was for the former so I stuck with the high dither setting thereafter and haven’t messed with it since."

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From another review:

"Then I decided to give the adjustable dither a try. Well, the Rotel can perform the impossible, nor could any other CD player I have ever heard, but it allowed the vocal chorus to stand out of the background as well as anything I've ever heard. It had a definite effect on the background vocals and apparent noise floor of the recording. Setting 2 seemed to be the best compromise for adding depth and clarity. So, the adjustable dither can be used to enhance a poor quality CD. A useful capability because about half of the really worthwhile performances are poorly recorded, mixed, mastered and transferred.
Adjustable dither. Not much has been said about dither since Bob Carver started playing with it many years ago, and his did not allow for multiple settings as I remember. The Rotel is the only recently available player available with this feature (other then the previous top of the line Rotel the 991 replaces) that I am aware of. It has proven to be useful with other recordings, particularly some of the early CDs that were particularly harsh. A smidgen, or sometimes a lot of equalization certainly doesn't hurt those either."