Lip sync error fixed with digital audio delays from Felston

DD540 - Customer Review

Thank you to A/V enthusiast Tom C for his very comprehensive review and graphics!

A few short years ago, A / V sync used to be the occasional minor annoyance. With the advent of LCD, DLP and Plasma TV’s, A / V sync issues are coming center-stage, due to the extensive video processing inherent in these designs. The real need for time compensation (audio delay) becomes apparent when viewing from a DVD player and listening to the audio through an A / V processor. Without providing delay to the audio bitstream, everything you watch will take on the characteristics of an old Kung-Fu movie.

Even though many current A / V processors can provide a delay up to about 60 ms, this is not nearly enough for many big-screen TV’s and monitors on the market, hence, the need for a very handy product like the Felston DD540 digital audio delay unit. This thoughtfully designed box provides 2 inputs and 2 outputs (1 Toslink and 1 Coaxial-more on this later) and provides 6 memory presets per input, user-settable from 0-680 ms in 1 ms increments. For 96 kHz applications, the maximum delay is 340 ms.

After adding a second DVD player to my system, I needed to augment the Felston DD340 I had been using and was very satisfied with, and so made the logical choice to add a DD540 as an expansion unit. The first thing I noticed when opening the box was the DD540 is just about the size of the earlier DD340, but with double the capability and just slightly more expensive! After power-up, I noticed its remote uses different codes, a most welcome feature for those who own both models. The remote allows selection of input 1 or 2 as well as delay setting presets, or simply scrolling the delay up and down to determine the appropriate setting for any monitor, all from the comfort of your easy chair. I also like the amber LED display (5 brightness levels) as well. Since I don’t have the luxury of a machine room, I’ve set the brightness to minimum.

Delay adjustment is fast and easy, the audio will smoothly mute (about 0.5 sec) when the memory setting is updated and after a few course adjustments, the exact setting can be determined. It took me less than 5 minutes to get the final setting, which turned out to be 175 ms to compensate for my particular 55” plasma monitor.

The DD540 also incorporates a “STANDBY” mode in which no delay takes place and the LED display is off, all the while retaining input switching capability. If that wasn’t enough, the DD540 has an automatic setting that senses activity and switches to the active input, available in both “STANDBY” and “ON” modes. The functions and settings I’ve mentioned are accessible on the remote and from the DD540’s front panel for the ultimate in user-convenience.


There’s one more important feature these clever folks have put in. There are 2 configurations available, “C1” and “C2”. (see illustration) The DD540 arrives set to “C1”, changing to “C2” is quick and easy. “C1” routes the “A” input to the “A” output and the “B” input to the “B” output. In this mode the inputs and outputs are kept separate so if you have 2 DVD players, you would be using 2 inputs on your A / V processor. Does your A / V processor have only 1 input or do you want to take up only 1 input? Then set the DD540 to “C2”. In this mode, you can use either the “A” or “B” input and send it to the “A” and “B” outputs so 2 DVD players would share 1 input on the A / V processor. Don’t have 2 DVD players? Then “C2” can double as a converter from Coaxial to Toslink or the other way around which solves the problem of some DVD players having one type of digital output while your A / V processor has the other type of digital input!

DD540 Output Configurations
Click for larger image

To sum it up, the folks at Felston have not missed a detail in the design of the DD540. This is a well thought-out product that does what it’s supposed to do and can be tucked out of sight if desired. I’m very happy to forget it’s there although the front panel and brushed aluminum chassis add a nice artistic touch to my component rack.

A job well done. Now, if only Felston would consider making cars ………………

Tom C
San Francisco, CA, USA