Common Confusion in Home Theater: Part 5

3d1This post is part of my series of blog posts and slideshows regarding topics of common confusion in home theater. In this post, I cover HDMI, including the issue of cable length and the controversial value of expensive cables.

  • Part 1: Volume and zero dB, updating firmware, Blu-ray disadvantage
  • Part 2: Speaker resistance, analog vs. digital amps in AV receivers
  • Part 3: PCM vs. bitstream, Blu-ray player upscaling/upconversion
  • Part 4: THX certification, DLNA network access, and distortion and THD
  • Part 6: Closed-back vs. open-back around-ear headphones
  • Part 7: Understanding your room and room dynamics
  • Part 8: Room correction, speaker position, and more room dynamics
  • Part 9: Ethernet, component separates, and broadband internet routers

Thanks for reading. Don’t forget to leave a comment if you have questions or feedback.

curtsig2 - trans
Curt Robbins


HDMI

HDMI, the acronym for High Definition Multimedia Interface, has finally replaced a variety of older connection standards in home theater (and computers). Even the most barebones entry-level TVs and receivers feature at least a couple of HDMI ports. It’s now a fully ubiquitous standard that’s going to be around for a long time. The greatest attributes of HDMI are that it is fully digital, carries both high-resolution audio and high-definition video on a single cable, and allows you to connect mobile devices like camcorders and smartphones to your home theater.

There are two types of HDMI cables: Standard and high-speed. Standard is capable of lower-quality (interlaced) 1080 video, while high-speed varieties provide you with the full quality of which Blu-ray discs are capable. Always purchase a high speed type, preferably one that supports 3D and something called Audio Return Channel.

Covers All Components

Old school analog connection standards, such as S-Video, composite audio/video, and component video are now dinosaurs, their bones scattered across the same wasteland as TV-top rabbit ear antennas and cassette tape decks. The fact that nearly all home theater components can be connected via HDMI makes things much easier. HDMI makes things so simple, in fact, that your biggest challenge becomes ensuring that you have cables of the proper length (so you don’t, for example, come up two feet short of what’s necessary to connect your receiver to your TV). Home theater is a lot nicer when the length of your cables, and not their type and expense, is your biggest concern.

Cable Length Limits

HDMI cables were originally developed to not exceed roughly 16 feet in length. The three foot (one meter) interconnects used to input Blu-ray players and set-top boxes to receivers aren’t a concern here. However, it’s not uncommon for a display panel TV to be on the other side of the room from the AV receiver feeding it. This is certainly an option that should be available to you when you’re planning or upgrading your home theater. However, this type of arrangement requires a long HDMI cable to be run through the walls or floor.

Lengths greater than 20 or 30 feet can, under the right conditions, produce undesirable results, such as no picture or an image that suddenly disappears. This is determined largely by the quality of the equipment connected to the HDMI cable, namely the receiver and display panel. Properly implemented HDMI ports that support the latest HDMI standard (obviously possible only on newer equipment) are more capable than those found on lower quality, older equipment.

There are two solutions for long HDMI cable lengths. First, you can purchase a hardware device that acts as an HDMI signal booster. An example is the Spectrum Electronics DSR-701 Digital Signal Restorer. This $280 device is well-reviewed and said to do an excellent job with cable lengths up to 100 feet. Second, you can convert HDMI cable to CAT6 cable using a special converter box or adapter, with the majority of your cable run in the form of CAT6. When the cable reaches your TV, it must be converted back to HDMI using a similar sister device. This allows lengths of up to 100 feet to be achieved with no video performance degradation. One reputable converter box set is the $140 Ethereal Home Theater CS-HDC5EXTD, which supports up to 90 foot (30 meter) cable runs.

If you’ve already installed a long HDMI cable in your floor, walls, or ceiling, you probably don’t want to endure the expense and hassle of installing an additional CAT6 cable. Thus, for many consumers with existing HDMI cable runs, something like the Spectrum Electronics Digital Signal Restorer will be the most straightforward solution—and possibly the least expensive when professional cable installation costs are taken into account. For new installations, I’d recommend running both high-speed HDMI and CAT6 cable, giving yourself the option of whichever solution most appeals to you (and further future-proofing your home theater). When possible and practical, a set of $60 to $150 HDMI-to-CAT6 and CAT6-to-HDMI conversion adapters is certainly more cost effective than a roughly $300 HDMI signal booster (saving you money for your speaker budget).

Are Expensive HDMI Cables Worth It?

All high-speed HDMI cables are the same. Let me say it again: All high-speed HDMI cables are the same! For the most part (at distances under 20 feet or so), an $8 cable performs just like a $200 cable. I know, it sounds like a conspiracy. But the fact remains that an expensive cable offers almost zero improvement over a cheap model (as long as it’s a high-speed type). You simply want to avoid crappy cables featuring poor build quality and little insulation (such as the two-for-$5 specials at your local discount store).

Don’t let a big box electronics store convince you that an expensive gold-plated HDMI cable is necessary for a quality home theater experience. Profit margins are highest on accessories like cables, cases, cleaning accessories, and spare batteries. Ironically, big box electronics retailers make the least profit on big ticket items like speakers, receivers, and Blu-ray players, so they try to make it up with accessories like cables. Salespeople argue, “If you spent all this money on your equipment, why shortchange your investment with cheap cables?” While this is great logic, and an argument frequently employed, it’s simply false in the case of HDMI.

In fact, the very nature of HDMI, which is a fully digital signal, means that it’s either nearly perfect or there’s no picture whatsoever. Unlike the old over-the-air analog broadcasts of the past, there’s no in-between where a fully digital video signal can degrade with snow or static, but still be viewable. Video and audio carried via HDMI is either there or it isn’t.

When I last upgraded my home theater, Best Buy tried to convince me to purchase several short HDMI interconnect cables costing about $85 each. An $8 cable from Amazon provided me with the same quality. Still not convinced? Check out the blog article Why All HDMI Cables Are The Same by Geoffrey Morrison of CNET.


Curt Robbins is author of the following books from Amazon Kindle:

You can follow him on Twitter at @CurtARobbins, read his AV-related blog posts at rAVe Publications, and view his photos on Flickr.

Common Confusion in Home Theater: Part 4

3d1As part of my series of blog posts and slideshows regarding topics of common confusion in home theater, below I cover THX certification, DLNA network access, and distortion and THD. This series features excerpts from my new Kindle book Home Theater for the Internet Age.

  • Part 1: Volume in a zero dB world, updating firmware, and the disadvantages of Blu-ray
  • Part 2: Speaker resistance and analog vs. digital amps in AV receivers
  • Part 3: PCM vs. bitstream and Blu-ray player upscaling/upconversion
  • Part 5: HDMI (including cable length and controversial expensive cables)
  • Part 6: Closed-back vs. open-back around-ear headphones
  • Part 7: Understanding your room and room dynamics
  • Part 8: Room correction, speaker position, and more room dynamics
  • Part 9: Ethernet, component separates, and broadband internet routers

curtsig2 - trans
Curt Robbins


THX Certification

THX is a collection of audio and video certifications for both commercial cinema (movie theaters) and home theater environments. THX was born at Lucasfilm Studios in the early 1980s, when George Lucas was producing Return of the Jedi, and gained its name from Lucas’ first feature film, THX 1138. Lucas was concerned that the fidelity and overall experience he was creating in his studio wasn’t being translated into commercial cinemas. The first THX certifications were granted to movie theaters, not home theater components.

THX offers several different types of certifications, including those for amplifiers and display panels. To obtain THX certification, a particular component model must pass 200 tests. While THX certification doesn’t guarantee you’ll like the image produced by a display or the sound flowing out of an amplifier, it does ensure a solid performance level. Buying THX-certified equipment helps you get reliable mid to top-tier components with respect to quality and performance. It has little to do with price, however. Products at several different costs may feature the THX logo. It is, however, more common on higher-end, more expensive components.

THX has also released an app for Apple and Android devices that helps calibrate your home theater’s video and audio. For more information regarding home theater calibration, see the Room Calibration section below and the Room Dynamics & Positioning section of the Speakers chapter.

DLNA Local Network Access

DLNA, or the Digital Living Network Alliance, is a communications protocol that works over both wi-fi and Ethernet that allows a variety of media files, such as family photos, music files (including high-resolution varieties), and videos to be streamed from one device to another on a local area network (or LAN). In home theater, DLNA is typically implemented in audio/video receivers and Blu-ray players and accesses a storage device or computer elsewhere on your local network.

Not only must your receiver or Blu-ray player support DLNA, but the device on your network—on which the media files are stored and from which you want to access them—must also include this protocol. This “sending” device on your network could be a personal computer (running Windows 7/8 or Mac OS X), a network storage device (officially called a NAS, or Network Access Storage), or even a top-shelf router with an attached flash drive or USB hard drive. As long as the two devices have a valid connection, enough bandwidth, and DLNA, you can begin routing photos, music, and video from your home network to your receiver or Blu-ray player, using your big display panel and listening to audio and music through your living room speakers.

However, simply because you can use DLNA to get a particular media file from a PC or storage device on your network to your audio/video receiver or Blu-ray player doesn’t mean the receiving device can necessarily decode it. For example, if you have a bunch of high-resolution music files in AIFF format stored on your network, but your receiver (or Blu-ray player) isn’t capable of decoding the AIFF format, DLNA won’t help. DLNA includes no decoding logic or special software for this purpose. It is merely a way for two devices on a home network to recognize each other and stream media files from one to the other.

Distortion & THD

All home theater components produce a certain amount of distortion, something that damages the quality of the sound but, at low and even moderate levels, typically can’t be perceived. This distortion is measured as THD, or Total Harmonic Distortion. In the case of an amplifier, THD is a measurement of the comparison of the receiver’s input and output signals (revealing how much the unit’s amp distorted the audio signal).

Instead of burying you in percentages and decimals, simply realize that lower THD is better. Any reputable brand of AV receiver, Blu-ray player, or speaker, however, will typically exhibit so little THD that it isn’t noticed (except at maybe the loudest volumes). This is true of models at all costs. According to Gary Altunian at Stereos.about.com, “In reality, total harmonic distortion is hardly perceptible to the human ear. Every component adds some level of distortion, but most distortion is insignificant and small differences in specifications between components mean nothing.”

Note that THD becomes worse as volume increases. Most THD ratings for receivers are based on the unit’s full output, or greatest volume (0 db, as you’ll learn below). As a rule of thumb, simply ensure that a receiver’s THD rating is below 1% (typical THD ratings on good receivers are far lower, falling between 0.03% and 0.08%, but measuring techniques vary and are sometimes heavily influenced by a component manufacturer’s marketing department). THD is just one measure of the quality of an amplifier or speaker. If you’re shopping for reputable receiver models, THD shouldn’t typically be an issue that influences your purchasing decision.


Curt Robbins is author of the following books from Amazon Kindle:

You can follow him on Twitter at @CurtARobbins, read his AV-related blog posts at rAVe Publications, and view his photos on Flickr.