There are many causes of lip sync error (see our Technical Info page for excruciating detail) but they all boil down to "delay of video more than audio allowing speech to get "ahead" of the lip movement that produced it". 

Sound "ahead" of the event that produced it can't occur in nature and is disturbing to our brains when trying to interpret it.

Ironically, high end display technologies with their focus on the ultimate "image" aggravate the lip-sync problem. Plasma, LCD, and DLP displays, with their sophisticated image processing and slower response times, delay the video signal but not the audio.

If you think you are alone with this problem, think again. Lip-sync error affects a huge number of users of modern plasma TVs, LCD screens and both LCD and DLP projectors.   And with HDTV,  the problem is even worse!

But now there is a solution!   The Felston DD540 digital audio delay can solve lip sync error for anyone who uses an AV amplifier with digital audio input.  It lets you add an audio delay to compensate for all the cumulative video delays - no matter what their source* - as you watch via remote IR control.


The Felston digital audio delay works together with your existing AV amplifier. It is compatible with any source that has a digital audio output - i.e. DVD players, and many cable/satellite/HDTV receiver boxes and with analog sources using a low cost analog to digital converter.

The DD540 connects between your sources and your AV amplifier and its IR remote gives you control over the delay of the audio signals reaching your amplifier.  You can delay the audio to match whatever video delay is causing the lip-sync error until you feel it is in "perfect sync".

DD540 Brochure with Specs

DD540 User's Manual