HDMI switch boxes

Lack of sockets on TVs is a common problem. For several years the best picture quality was via component video or RGB Scart but you'd often find only one compatible TV input for each, if at all. Manufacturers gradually increased the number of RGB-ready Scarts to two, three or even four, which was fine for those with one or two digital TV boxes and DVD player and perhaps a DVD recorder too.

Now the industry is adopting HDMI (high definition multimedia interface), an all-digital AV connection that generally gives a much improved picture. It's smaller, neater and suffers less conspicuously from interference that can blight analogue pictures. HDMI sockets are increasingly common in flat panel LCD and plasma screens as well as front and rear projection systems. However, consumers are coming up against the same lack of sockets as many products, especially those snapped up by early adopters, only have one HDMI input.

For a while this was not a problem but already you can find yourself with at least two or three HDMI-equipped products, from Sky HD boxes to Telewest's TVDrive PVR, an upscaling DVD player or recorder and, soon, next-generation disc players and games consoles such as HD-DVD decks and the Blu-ray disc-based Sony PlayStation3. This is something that AVReview readers are certainly concerned about, as our recent poll of HDMI inputs showed. Rather than buy a new TV at vast expense, there is a simpler and less expensive answer. Just as you are able to buy multi-Scart adaptors, you can get HDMI switch boxes in various permutations, so you can plug several HDMI products into one box and switch between them, connecting a single output to your TV or projector. If any of your kit has an older style DVI-D socket, you can use adapter leads to connect to HDMI too.

Cost considerations
Due to the licence fees involved and the fact that any HDMI accessory is still something of a niche item compared to mass market gadgets, HDMI switchers are still pricey. The cheapest at the time of writing appears to be the Octava HDS3-UK 3-into-1 switching box at £120 from TMF Solutions, closely followed by the Keene 3:1 Switcher at £125 from Keene and Lindy's three-port HDMI Switch Remote at £149. As their names suggest they allow up to three HDMI inputs, though four, five and even six-way switch boxes exist. Some boxes also split digital audio into a separate output so you don't get into a tangle with your surround sound amp as well.

At the higher end of the scale is Germany's Oehlbach with its HDMI Switch 4100, a four-to-one box costing £595. There's also a smaller, two-to-one model at £395. We ran a 4100 model and compared it to Octava's three-to-one box and could find no particular difference in performance except that on a practical level the Oelhbach's automatic switching – to detect a player or HDTV box being turned on – was more reliable. The Octava has a credit-card sized remote, which is of course crucial if you need to switch sources manually without leaving the sofa.

Cost and features are another factor to consider though. Oehlbach's models are certified to comply with the HDMI (v1.2) specification, so progressive scan resolution images at up to 1080p are supported. HDMI switches should also be compatible with HDCP (high-bandwidth digital content protection) as most broadcasters and disc players using high definition outputs may use this anti-piracy system. If there are problems with HDCP, then you may get a reduced image quality on your TV, or no picture at all.

Picture improvements
HDMI switchers can help keep your picture and sound in check, too. Most offer built-in amplification to boost signals travelling through long cable runs. This is particularly important if you have a ceiling-mounted projector or any situation where your source equipment is some distance from the TV. The picture can degrade over cables that are not of the highest quality or are more than nine metres long, especially if you are using 1080p.

Another benefit of switchers is jitter correction that can ensure that there are no timing errors in the signal. Connecting some HDMI products directly to a plasma or LCD screen can result in incompatibilities such as audio dropout or small glitches in the image. A switchbox often eliminates these. If you want these advantages but have no need for a switcher, then there are various inexpensive HDMI extenders on the market offering similar benefits.

A drawback with current HDMI switchers is that they may not be fully compatible with the newly announced HDMI v1.3 specification. However, if you have been using a slightly older surround sound receiver with HDMI switching, you may find that it's only compatible with v1.1 of the spec rather than v1.2 (which added Super Audio CD support). However, any HDMI switch box can get you out of a tight spot if you want to add more high-definition items to your home entertainment set-up.

Recommended HDMI switchers
AVR has tried all of these boxes. This is what we found…

Octava HDS3-UK £120
Octava website Octava products
An affordable but good quality 3:1 HDMI switcher with proprietary technology to improve digital video signals; one of several switchers and extenders from Octava.

Zektor HDVI5 £365
Zektor website Zektor products
This versatile 5:1 box uses DVI but can carry HDMI audio through all ports using standard HDMI-DVI cables; it also has five optical and coaxial audio inputs including cross conversion and three digital outputs.

Gefen 4×2 HDMI Switcher £446
Gefen website Gefen products
Accessory specialist Gefen has a bewildering array of digital switch boxes for almost any AV combination; this one has four HDMI inputs and two (mirrored) outputs along with digital audio extracted to a coaxial output.

Oehlbach HDMI Switch 4100 £595
Oehlbach website Oehlbach products
An easy to use 4:1 HDMI box that boasts super-efficient auto switching and high quality German engineering, though for this price that's the least you'd expect.

Writer Ian Calcutt

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