This is a review and detailed measurements of the Felston DD740 Digital Audio Delay/ Lipsync Correction and input switcher. It was sent to me by the company and costs US $249.
As you can see, the DD740 is a compact device. The main controls are input selection and changing of the delay in milliseconds (or optionally 1/3 msec). Up to 9 settings can be stored for each Toslink optical or Coax input and recalled using the remote:
I like the super responsive change of the delay.
Felston DD740 Measurements
The first thing I measured was the accuracy of the delay and it was right on the money. This is an example of setting the front panel to 50:
As you see, it is accurate to two decimal places.
The only other test I could think of was jitter:
Jitter is of course worse than the Audio Precision APx555 analyzer but peak is about 120 psec which is reasonably low. As a comparison, you need 500 psec of jitter to obliterate one bit of 16 bit audio. Given audio sync issues, I will take some jitter every day of the week and twice on Sunday!
Conclusions
As a person who has worked in broadcast video industry and gotten grilled and beat for incredibly small amount of audio/video sync issues, I am hugely bothered by the poor sync between audio and video in broadcast, streaming and stored content. Not only each source is different, but also from program to program! Audio is slaved to video and getting the two in sync is more of an art and science at times and naturally, many encoders (offline or online) get it wrong. It is so annoying to set the delay on one channel of cable TV, change channel and have it be out of sync again! With DD740 you can make corrections on the fly using the remote. To the extent the delay differential is channel/source specific, you can put it in memory. Or make quick fine refinements as needed.
I am happy to see a standalone product at reasonable cost solve this issue as the industry syncs into worse and worse problem in this domain.
I can recommend the Felston DD740 for its unique functionality.
-----------
As always, questions, comments, recommendations, etc. are welcome.
Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
As you can see, the DD740 is a compact device. The main controls are input selection and changing of the delay in milliseconds (or optionally 1/3 msec). Up to 9 settings can be stored for each Toslink optical or Coax input and recalled using the remote:
I like the super responsive change of the delay.
Felston DD740 Measurements
The first thing I measured was the accuracy of the delay and it was right on the money. This is an example of setting the front panel to 50:
As you see, it is accurate to two decimal places.
The only other test I could think of was jitter:
Jitter is of course worse than the Audio Precision APx555 analyzer but peak is about 120 psec which is reasonably low. As a comparison, you need 500 psec of jitter to obliterate one bit of 16 bit audio. Given audio sync issues, I will take some jitter every day of the week and twice on Sunday!
Conclusions
As a person who has worked in broadcast video industry and gotten grilled and beat for incredibly small amount of audio/video sync issues, I am hugely bothered by the poor sync between audio and video in broadcast, streaming and stored content. Not only each source is different, but also from program to program! Audio is slaved to video and getting the two in sync is more of an art and science at times and naturally, many encoders (offline or online) get it wrong. It is so annoying to set the delay on one channel of cable TV, change channel and have it be out of sync again! With DD740 you can make corrections on the fly using the remote. To the extent the delay differential is channel/source specific, you can put it in memory. Or make quick fine refinements as needed.
I am happy to see a standalone product at reasonable cost solve this issue as the industry syncs into worse and worse problem in this domain.
I can recommend the Felston DD740 for its unique functionality.
-----------
As always, questions, comments, recommendations, etc. are welcome.
Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
