Some cables can run twenty metres. Some top out at five. In this article, we examine the limitations on a variety of common formats, and what the pitfalls are to breaking through the length limit barrier.
The concept of a home theatre or dedicated entertainment room was unheard of thirty years ago. Back then, living rooms didn't need to cater for 85" televisions and 5.1 surround sound, so short cables set the standard which continues to this day.

 

 

 

 

 

But now, we spend the bulk of our waking lives looking at electronic displays, and the need to get AV signals from source to display over longer distances has become more important than ever; both in our homes and out. But not all cables have kept up the pace.

Below, we detail the current limitations of the most common digital and analogue formats – you can read about the only format that affects you, or read the whole article to wield the power of a home theatre titan!

HDMI

HDMI is so popular that its old length limits have been blasted out of the water with a variety of innovations which all come in at different price points. We'll look at each of the options we stock here at Cable Chick:

• Basic HDMI: This covers cables that meet the HDMI certification standard and don't have anything extra built in. These cables range from our cheapest to our most high-end Amped Onyx series. They contain the required 19 cores of high-grade copper, plus varying degrees of shielding in line with their price point. More expensive cables can accomodate higher resolutions over longer lengths and also work better with splitters and switches. Basic and budget level HDMIs are best for short lengths and direct connections between powered sources and displays. Alone, these cables can take HDMI 20 metres.
  See our longest regular HDMI cable here!

• Boosted HDMI: HDMI cables which have a booster integrated into their structure use the 5v power rail of the HDMI signal to carry the data further without loss of fidelity. This boost is commonly used to make longer cable runs, but it can also be used to make a short cable thinner and much more flexible. HDMI cables with integrated booster chipsets are more expensive than their basic counterparts, and so far only cater to 1080p content due to the loss of bandwidth over the extended length, but they can reach 40 metres.
  See our longest Boosted HDMI cable here!

• HDMI over CAT: Using Cat5 or Cat6 cables to extend an AV source is not a new concept, and HDMI can make use of this technology for stable extended runs – sometimes even using existing network cabling. Due to bandwidth limitations, most CAT extenders only support 1080p, but some can handle 3D, too. Configuration is more complex than regular cables, and interference can be a big problem in some environments, but with a good HDMI over Cat5/6 Extender, you can run 50 metres.
  See our Premium HDMI Extender Kit here!
       Special Note: Some devices can also leverage Ethernet-based LANs for video and audio extension from a PC. See our PC to HDMI & VGA over LAN converter here!

• HDMI over Fibre Optics: Fibre Optic kits for HDMI carry the highest price premium of all, but they have the capacity to outstrip copper based cables for distance by a large margin. The added benefit to this cable type is flexibility. The Optical core is much smaller than Boosted HDMI, but can go the same distances. As of this writing, Cable Chick's longest HDMI over Optical Fibre Cable is 45 metres, but some companies have kits which run much longer (and cost far more!)
  See our HDMI over Fibre Kit here!

• HDMI over Wireless: Wireless technologies vary between models, but one thing they have in common is they don't generally go as far as cables do. Line of sight is 10 to 15 metres, and through walls can be as low as 5 to 8 metres. Unless you can't run a cable at all, a lead will beat Wireless every time. Wireless is also limited by bandwith to 1080p, and only the best units can handle 3D.
  See our Wireless HDMI Kit here!

Want to know more about separately available HDMI booster accessories? We cover them in our article on Couplers and Adapters (*coming soon!).

 

DVI-D Dual Link

DVI has three main flavours, but the two we deal with most of all are DVI-D Single Link and DVI-D Dual Link. The Single-Link variation is basically the same as the video portion of a HDMI signal, and for resolutions up to 1080p, it can easily run 15 metres. By using HDMI adapters, you can use boosters to go even further.
See our longest DVI-D cable here!

However, when you push past Full HD and into the world of 27" and 30" computer monitors, Dual-Link bandwidth is required to get the signal across. At resolutions up to 2560x1600, your cable run length is limited to 5 metres.

At present, there are no reliable booster technologies which can be leveraged for DVI-D Dual Link at higher-than-HD resolutions. If you try to use a cable longer than 5 metres, your display will automatically drop down to 1080p simply because it has run out of bandwidth over the longer cable.
See our 5 metre DVI-D Dual Link cable here!

 

Display Port

Because DisplayPort was so ahead of its time in terms of bandwidth and resolution capability when it was launched, strict limits were set on what cable lengths could be certified. This decision limited confusion in the market place, but set the maximum limit for a certified DisplayPort cable at 5 metres.
See our longest DisplayPort cable here!

Using couplers to join two certified DisplayPort cables together for a run longer than 5 metres will result in loss of signal. There is currently no workaround for this length limit.

 

VGA

Like Dual-Link DVI, VGA accommodates many resolutions, each of which requires a different amount of bandwidth. As cables get longer, the available bandwidth decreases and with it the highest potential display resolution is lowered. A short VGA cable can manage 1920x1080 without trouble. A long VGA cable may top out at 1024x768, and our longest offering may struggle to reach 800x600.

• Basic VGA: For a single cable, it's always important to consider your requirements and the installation environment before opting to use a VGA cable over 5 or 10 metres. But if resolution isn't an issue, we stock all the way up to 40 metres.
  See our longest VGA cable here!

• VGA over CAT: To overcome these limitations, we carry a VGA over CAT5/6 Extender kit. With this sender/receiver pair, bandwidth is boosted considerably – allowing for 1024x768 to reach 75 metres, and 640x480 to reach 300 metres.
  See our VGA Extender kit here!

 

USB 2.0 & 3.0

The new SuperSpeed USB standard has its own set of rules for maximum length, so we'll look at each standard separately. Because of its age, USB 2.0 has more workarounds on the market than USB 3.0, but come with some important caveats.

• USB 3.0: Extra pins. Higher speeds. More bandwidth. The ability of USB3.0 to achieve these accolades relies on the cable most of all, yet the USB 3.0 standards don't specify a maximum cable length. However, our testing has shown that there is a definite failure point for USB 3.0 (especially when using portable hard drives). For devices requiring power over USB, 2 metres is foolproof. For self-powered devices using an internal battery or direct wall socket connection, we carry a 3 metre cable.
  See our longest USB 3.0 A/B cable here!

• Basic USB 2.0: It's everywhere. From flash drives to digital cameras and from portable hard drives to printers, you can't escape USB 2.0! Because of its ubiquitous nature, USB has to be a Jack of All Trades in terms of power delivery and bandwidth. As such, regular USB 2.0 cables have a limit of 5 metres to meet the certification standard. You can go longer with USB extensions, and data may still get through, provided that the device (hard-drive, printer, etc) is independently powered.
  See our longest USB 2.0 A/A cable here!

• Boosted USB 2.0: We stock two lengths of USB 2.0 cable which feature integrated repeater/booster chipsets, both of which can be daisy-chained repeatedly. The downside to this method is that the 5v power rail is used for boosting, and is therefore not available for powering a connected device – great for printers plugged into mains power, but not so good for portable hard drives. Our boosted USB 2.0 cables come in 5 metres and 12 metres, and can be chained together for runs up to 36 metres!
  See our longest Boosted USB 2.0 cable here!

• USB 2.0 over CAT: Based on a similar principle to HDMI over CAT, USB 2.0 can also be greatly extended using a Cat5 or Cat6 cable. You'll experience the same limitation on USB-powered devices as the booster chips above, but a good link can get your USB 2.0 signal to go 80 metres.
  See our USB 2.0 Extender kit here!

• USB Hub Daisy-Chaining: It may be possible to string together multiple powered hubs to extend the range of USB 2.0 and/or USB 3.0. So long as each hub gets it power from an external (non USB) source, it is theoretically possible to exceed the above length limits. We haven't tested this ourselves, so we don't know what the limit is...
  See our Powered USB Hub here!

 

TOSLINK Optical Audio (SPDIF Optical)

Toslink (optical SPDIF) relies on a pulse of light to operate, and as such doesn't suffer from signal loss due to electromagnetic or RF interference. It is also unaffected by electrical resistance, but there are two important aspects which play a role in length limitations: The clarity of the optical core inside the cable, and the strength of the light source inside the hardware.

Toslink cables intended for consumer-level use contain plastic optical fibres. This makes them robust, flexible and great for lengths up to 15 metres - provided that the source device has a strong enough output.
See our longest TOSLINK cable here!

It is possible to track down Toslink cables that have glass fibre cores. These cables can potentially go much, much farther than plastic, but their fragility and extreme cost make them unworkable (and unnecessary) for most homes. If you are finding that a 15m TOSLINK cable is failing, it's more likley the source device is too weak rather than the cable being faulty.

 

Analogue (RCA) AV

Analogue formats bear a unique burden in that there is no parity check to ensure that the display device is receiving uncorrupted data. Coupled with the simpler technology which powers these standards, they suffer greatly from signal loss over long lengths.

Put simply, the farther you go with analogue, the worse it looks or sounds. Sure, you can run a 50 metre component video cable (if you could find one) but the quality of the image at the far end would be horrible. It's here, with analogue, that cable quality matters most.

• CVBS & YPbPr Video: Our longest length in these formats is 20 metres, but your mileage will vary greatly between our cheapest and most expensive options. If you want a crystal-clear signal over the longest length, only Amped Onyx can provide the best signal, and after that it comes down to your environment and source quality.
  See our best and longest RCA Video cable here!

• 2RCA Audio: Analogue audio can be more forgiving than its video counterpart, but cable quality still has a profound affect over longer lengths. With 2RCA, you can easily go 30 metres.
  See our longest 2RCA cable here!

• Audio Mini Jack: With 3.5mm audio, Cable Chick stocks a maximum length of 10 metres. Why? Because 3.5mm cables are most commonly used for personal headphones where any dips in audio quality become very apparent. Yuck! While we don't stock pre-wired 6.5mm audio cables (at the moment) using an adaptor works just as well over the same 10 metres.
  See our best and longest 3.5mm Mini Jack cable here!

 

Speaker Wire

Bare Speaker Wire (the kind which is just twisted copper strands in a PVC sheath) is a special case among all of the cable standards we'll discuss here. Because amplifiers and home theatre receivers can have different power ratings (watts and ohms) the cable itself has to be capable of carrying a range of power levels without overheating and catching fire. A beefy thousand-watt amp driving big speakers through thin wire will get you a visit from the fire department quicker than it'll give you good sound.

Cable Chick currently only stocks 16 AWG and 12 AWG speaker wire. 16AWG is a great baseline because it's the thickest gauge that can easily fit into the spring-clips found on most entry-level home theatre and audio gear. 12AWG is just over double the size, and it caters to pretty much everything else you'd be willing to put in your home. If you're looking at a sound system which needs heftier cable, the police will be responding to noise complaints before you get to stretch its legs!
See our 16 and 12 AWG Speaker wire here!

In terms of length limitations, we've adapted this handy chart to give you an idea of what's possible. Remember that most home theatre speakers are 8 Ohm, so always be sure to match your amp to your speakers when purchasing components separately. It's vitally important if you don't want to blow your speakers that both the Wattage and the Impedance are identical.

In Summary

So there you have it! Our crash-course in cable lengths. We realise this isn't a definitive guide, but for the sake of simplicity we didn't discuss solutions we can't source, or that fall under industrial or commercial applications. If in doubt, always use the shortest length of cable you can live with, and for cables like HDMI and DisplayPort, ensure they're certified by the industry bodies which control them before purchase (ours are!).

And of course, what kind of article would this be if we didn't have a huge chart with all of this info in one hit?

Still stuck?

There are some standards we haven't covered here – like microphone leads – mainly because we anticipate customers will have some prior experience when working with them. But if you still have a burning question, simply fill in the enquiry form on our Contact Us page and we'll do our best to help you out!

---