Sound... & Vision

Q. I read that the newer HDMI version 1.3 effectively solves the lip-sync issue that can sometimes pop up in HDTV broadcasts because of the digital audio being quicker than the video. I am considering a receiver upgrade. Would you recommend looking for a receiver with HDMI 1.3?
Shawn Crandall
Via e-mail

A. Al Griffin says: You're right: High-definition video requires more intensive processing on the part of your TV than digital audio, which is why you'll sometimes get a time lag as long as 50-100 milliseconds when watching high-def programs — enough to cause a visible gap between picture and sound (the lip-sync problem). HDMI 1.3 can correct for this issue by identifying lip-sync problems within the device chain and instructing components to compensate for them. For example, a TV requiring 50 ms of audio delay to sync up sound and picture can communicate that information to an A/V receiver, which delays the signal accordingly. Since you're looking to upgrade your A/V receiver anyway, you should consider a model with HDMI 1.3 switching. (Models with that capability should arrive sometime in mid-2007.) But to take advantage of the lip-sync correction feature, you'll need both a receiver and a TV with HDMI 1.3 connections.

Intermittent Tweeter

Q. I have a pair of tower speakers. When I first turn on my amp, I get no sound from the ribbon tweeter in one of the towers. I can get the drivers working by turning the volume up, and once it's working, I can turn the volume back to listening level and things work normally until I power down at the end of the day. Is my amp at fault or the speaker? Would switching amp/speaker connections fix it?
Sean Echevarria
San Mateo, CA

A. Ian G. Masters says: Since it's only in one channel, you can eliminate (or confirm) the amplifier as the culprit by swapping the left and right connections. If the problem shifts to the other channel, the amp is doing it; if not, it's a problem in the speaker or the wiring between it and the amp. Since the problem affects only the tweeter, it's not likely to be caused by the external wiring unless your speakers are biamped. If they are, tightening up the connections might solve the problem. If that doesn't help, it's mostly likely occurring inside the speaker box, and that will require professional service.

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