Home Theater: Cables, Keystone, Lossless

Cash Grab
I have long heard and read that "high-end" HDMI cables are a cash grab and offer minimal if any benefit when compared with bargain brands. Are there real gains in "high-end" HDMI cables? If so, which companies would you suggest looking into?

Vir Sodhi

In my opinion, expensive HDMI cables do not offer any significant benefit over bargain brands when it comes to short cable lengths. However, I do recommend name brands for cables longer than 10 feet or so. I don't think there's any need to spend hundreds or thousands of dollars on any HDMI cable unless it needs to run many tens or hundreds of feet, in which case you need an HDMI extender that sends the signal via CAT5 or fiber-optic cable, and such a system can cost big bucks.

Keystone Kops
I am building a dedicated home theater, and I have completed most of the design work. One of the last details is the projector position. I have a 100-inch 16:9 screen and the Panasonic PT-AE3000.

I have read that it is better to shift the image optically rather than using keystone correction, so I am considering having the projector mounted lower from the ceiling. How important is it to reduce/eliminate keystone versus image shifting? Should I position the projector so keystone is zero? Also, how important is the distance between the screen and projector? Currently, the plan is within the recommended range of 10 to 19 feet for a 100-inch screen.

Charles Ballaro

First, let me clear up any confusion about the function of keystone and image shifting. Keystone is a setting found in most projectors that compensates for non-perpendicular placement. If the axis of the projector's light path is not perpendicular to the screen, the image will not be rectangular—one side will be taller than the other and/or the top or bottom will be wider than the other. Keystone correction compensates for this by digitally processing the image to form a rectangle.

By contrast, optical image shifting (sometimes called lens shifting) simply moves the entire image up, down, right, or left to align it with the screen. This lets you place the projector off-center with respect to the screen and still align the image with the screen. In this case, if the light path is perpendicular to the screen, no keystone correction is required.

You should absolutely avoid keystone correction at all costs. The digital processing it employs reduces resolution and can introduce ugly artifacts. You should mount the projector so its light path is perpendicular to the screen. Then you can use lens shift to align the image with the screen.

As for the distance between the projector and screen, which is called the throw distance, it's better to place the projector as far as possible from the screen. This allows the light to pass through a smaller area in the center of the lens, resulting in less potential for chromatic aberration.

Lossless = Better
How much difference is there between Blu-ray lossless audio and regular Dolby Digital and DTS? Is it worth buying a new receiver only for this reason? I have a Yamaha RX-V1500 with optical inputs for my HD DVR, PS3, and HD DVD player. Do you think it is worth upgrading my receiver?

Randy Nelson

There is a big difference between regular Dolby Digital/DTS and the lossless audio formats found on Blu-ray (and, for that matter, HD DVD), though you probably won't hear all that much difference if you have poor-sounding speakers. If your speakers are reasonably good, I do think it's worth upgrading your receiver for this reason.

If you have a home-theater question, please send it to scott.wilkinson@sorc.com.

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Reader Comments

Posted Fri Apr24, 2009, 5:58 PM — By Todd Jiang

Home Entertainment magazine had an article about lossless audio a few months back. Geoffrey Morrison and one of the writers visited Dolby and DTS screening/critical-listening rooms (that adhered to ITU standards) and the respective companies did blind, random testing between the lossy and lossless soundtracks that were sourced from the same master soundtrack. H.E.M. concluded that even with great equipment, in an acoustically controlled envirement there was a subtle difference between the full bitrate core (1.5 Mbps for DTS and 0.64 Mbps for DD) and the lossless track. In fact, the writer couldn't tell the difference between DD+/DTS-HD and TrueHD/DTS-MA, although Morrison could, and while they both heard a difference between the core and the DD+/DTS-HD tracks, it wasa also subtle, not night nd day. It's nearly impossible for ANYONE to do this at home because the lossy tracks are usually sourced from different masters as the lossless tracks (at the consumer level). Do most homes have an itu-spec thea

Posted Fri Apr24, 2009, 9:29 PM — By Scott Wilkinson

That's very interesting. I've never participated in a formal test, but in my informal comparisons, I've always heard a pretty big improvement with Dolby TrueHD and DTS-HD. But now you've got me wondering...I'm going to try to arrange a formal test such as the one Geoff and his writer engaged in. When I do, I'll report my findings on this website.

Posted Fri Apr24, 2009, 11:05 PM — By Bill

Yes Scott, I'd love for you guys to do one. If you can even get as elaborate as the flat panel face off, that'd be great. It may not be as interesting as the tv face off, but it just may settle the debate between lossless and lossy codecs once and for all.

Posted Sat Apr25, 2009, 9:15 PM — By Ron W

As ironic as it might sound, it is true that superior equipment DOES minimize the difference between lossy and lossless soundtracks. One of the issues that wasn't mentioned though, was that you are dealing with differences in SPL level much like the early differences between DD and DTS on Standard DVD's. At a given volume, to my ears anyway, the lossless soundtracks are louder than the lossy ones. I am assuming they negated that difference in their tests. One advantage of the new surround codecs, at least in DTS Master Audio, is the final emergence, however few at this point, of 7.1 soundtracks.

Posted Tue Apr28, 2009, 12:46 PM — By Jerry

Scott, Is it possible that on HD discs that offer both Dolby TrueHD and the lossy version on one disc, the plain DD soundtrack is an inferior, poorly mastered one--even more so than what is usually found on 480i discs? I have watched a high def disc with the lossless and lossy tracks (I think it was V for Vendetta) and compared them side by side on a superb, calibrated system, and found the difference so STRIKING, it was beyond belief. I thought it was due to the lack of effort placed on the old DD soundtrack, because it was almost unlistenable in comparison. Make sense?

Posted Tue Apr28, 2009, 3:19 PM — By EWL5

I gave a double blind test to 2 people using the movies 300 (for TrueHD vs DD) and Master and Commander (for DTS-HD MA vs DTS). My results showed that the % correct by my subjects was worse than flipping a coin (it was about 40%). I'm sure if more people did a double blind test, they would realize they can't reliably tell the difference either!

Posted Thu Jun11, 2009, 10:58 AM — By Garlando

I want to hide my components in a closet! My Tv is about 30ft away, so I was going to purchase about a 50ft HDMI cable? Will this affect my picture and soung alignement? Or do I need something to boost the signal, or will it be ok with a good set of HDMI wires? What kind do you recogmend also? Another question, do I need to vent the closet to allow the components to breathe?

Posted Mon Jul27, 2009, 11:10 PM — By Paul McDonald

Scott, Can you provide an update on Whole House Digital Interface, and who will be offering this system. I need info on upcoming systems where I can mount plasma tvs or LED flat screens snugly on the wall without all the audio & video wires running all through the walls. Many Thanks

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