Audio Sync Problem

Audio Sync Problem: a reader asks…

I have a Samsung HW-MM45C sound bar. That is connected to my RCA LED55G55R120Q TV via a HMDI cable coming from the Direct TV box. I have a PLYE P2002ABT1 Amplifier that I have 5 rooms with speakers hooked up to. It only has 1 pair of audio input jacks. I have the Direct TV box audio out jacks connected to my Bose CD player input jacks and the out put jacks connected to the amplifier. My problem is when I use Pandora the sound bar and hours speakers are not in sync.

You didn’t say, but I’m guessing you’re using the DirecTV box for Pandora – if you’re using a different source to play Pandora, the below advice may need tweaking. I’m also guessing that you have an optical cable running from the RCA TV to the Samsung sound bar. Pandora has an app for DirecTV which makes it easy to use without having to switch input sources for your home theater/audio system equipment.

The problem in a nutshell is that you are mixing digital audio signals and analog audio signals. This results in a synchronization problem because the audio takes more or less time to reach the speakers, based in part on the different connections and devices (e.g., ‘path’) the signal has to go through:

  • Your digital audio circuit path is from DirecTV HDMI jack, outputting Dolby digital 5.1 audio through the HDMI cable to the RCA TV and (presumably) from the RCA TV through an optical cable to the Samsung sound bar.
  • Your analog audio circuit path is from the DirecTV’s red/white RCA jacks (that output 2-channel analog stereo audio) which goes via RCA cables to the Bose CD player, and from that via RCA cables to the PLYE amplifier, which amplifies and delivers the analog audio to the room speakers.

Since they are different signal types and paths, the speed at which they are delivered to the speakers isn’t going to match.

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Your Samsung sound bar remote (manual online here) has a control (page 21) that lets you adjust the audio sync from 0-300 milliseconds. That’d be the first thing you could try to get the audio to match up.

But I’m guessing the problem is greater than can be fixed with a 300 millisecond adjustment. Likely the room speakers are running a half-second (500 milliseconds) ahead or behind the sound bar. If this is the case, there’s no easy solution as your PLYE amplifier has no audio sync adjustment (online manual here). Presumably, neither does your Bose CD player. Your RCA TV (online manual here) doesn’t show any capability for adjusting audio sync, and likely neither does your DirecTV box.

One thing you could try is to run the analog audio through splitter cables (such as these for $26 from Amazon.com) from the DirecTV so that 2 cables go to the Bose and 2 cables go to the AUX inputs on the sound bar. But that may still have a sync problem because of the Bose and PLYE parts of the room speaker signal path. You might have to add a synchronization corrector to your setup (such as this $84 box at Amazon.com) and experiment which side to use it on (the RCA cables either between the DirecTV and Bose, or between the DirecTV and Samsung sound bar) and play with the settings to get them to match synchronization (by ear).

Most people use a home theater receiver to manage and process digital audio so that the output is all processed the same way. That eliminates sync issues. I get that you were probably using existing equipment, but unfortunately there’s no clean way to get good synchronization without help (i.e., additional equipment).

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