An HDMI splitter is a fairly simple piece of technology that allows you to transmit audio-visual data from one HDMI source – regardless of the size of cable like mini and micro (our tutorial on the differences) – to two HDMI receivers. This can be useful in situations where you have a television and a sound system you want to feed an external source to, but your devices don’t have HDMI ARC or eARC. It can also be useful if you want to display the content from one source on multiple TVs.
An HDMI splitter takes the HDMI signal from one source and splits it into two identical sources. HDMI splitters can either be passive, simply splitting the signal, or active, adding some additional power to the split signals to compensate for the loss of cutting a signal in half.
Passive HDMI splitters are usually sufficient for most applications. If, however, you have a setup involving long cable runs, then you should use an active HDMI splitter.
There can be some confusion around HDMI splitters. Sometimes, a similar technology, the HDMI switch, is confused for an HDMI splitter. An HDMI splitter splits a channel from a common source to multiple outputs.
On the other hand, an HDMI switch manages multiple source inputs to transmit to a single output (most receivers act like HDMI switches). Thus an HDMI splitter will transmit to all available channels while an HDMI switch will only transmit to one.
How Does an HDMI Splitter Work?
An HDMI splitter is pretty intuitive in its design. Almost universally, it will take a single incoming HDMI signal and output it to multiple HDMI outputs all at the same time.
This means you will need additional cables for each device you intend to output the source to. Although passive and active HDMI splitters work slightly differently, this basic principle is the same.
An HDMI cable has 19 wire pairs that terminate in the same number of pins on the HDMI plug. Each of these wires transmits different information electronically via digital signals. This includes not only audio and visual data but also information about the specific devices and commands you might find on a remote control.
An HDMI splitter duplicates, or splits, each of these wire pairs. As a result, you end up with two or more sets of 19-wire-pairs that feed into as many HDMI jacks.
For passive HDMI splitters, that is the long and short of it. For active HDMI splitters, there is another step.
One of the drawbacks of splitting an HDMI signal (or any electrical signal for that matter) is that you technically cut the power of each output signal (more on this later). For this reason, you will almost never find a passive HDMI splitter with more than two outputs.
To compensate for this power loss, active HDMI splitters add power to the HDMI signal. This is done by using an external power source (usually a
power outlet) to power the signal. The original signal is passed through an electronic component called a transistor. This signal acts as a gate, allowing and restricting the wall power source (significantly reduced from the 120 or 240 volts that come out of the wall) as the signal passes through it. You can think of it as a megaphone but for electricity.
When Would You Use an HDMI Splitter?
There are numerous scenarios in which an HDMI splitter might come in handy. The most common uses for an HDMI splitter are when you have separate audio and video devices or when you want to display the output to multiple devices. The particular application will determine whether you need an active or passive HDMI splitter.
Passive HDMI Splitters
For most basic uses where all HDMI connections will be contained to a TV console or similarly small space, a passive HDMI splitter (link to Amazon.com) should be sufficient. As long as the signal has not been altered by interference, it should be able to come through with no noticeable difference.
In the case of a single source outputting to an audio and a visual output, an HDMI splitter should be your last resort. A far more preferable way to connect the devices is to take advantage of HDMI ARC or eARC. This will require your display device and your audio device to both have an HDMI ARC or eARC port. This will usually be labeled as such next to the port itself.
To set it up, hook up the external source to either the display device or the audio device on a different channel. It’s generally a good idea to use the device with the most HDMI ports as the central device. Then, connect the display device and the audio device on the HDMI ARC or eARC ports.
If you have HDMI ARC instead of HDMI eARC, you will need to check your device manuals to enable it on each device. If you have HDMI eARC on all of your devices, setup will be automatic.
The advantage of using HDMI ARC or eARC over an HDMI splitter is that it allows you to take advantage of Consumer Electronic Control or CEC. This allows you to use one of your device’s remotes to control all of your devices. It also synchronizes your devices so that they all have one master volume.
Active HDMI Splitters
You will want an active HDMI splitter (link to Amazon.com) if you are outputting to more than two destinations or if you are doing long cable runs.
As previously mentioned, when you split any electronic signal, the resulting signals will be weaker than the original. Splitting it more than twice will make the signal too weak. Further, a weakened signal, even one that is good for short lengths, may be more susceptible to interference over longer runs of cable.
An active HDMI splitter will allow you to split your source HDMI signal without any notable loss in signal integrity. This allows for an HDMI signal to be split multiple times with some splitters having as many as eight outputs. It also means that you will be less likely to pick up radio frequency interference.
Will an HDMI Splitter Degrade the Picture or Audio Quality?
As previously discussed, a passive splitter will technically mean a reduction in signal strength. However, for most uses where you are likely using shorter cables, this shouldn’t matter much. The reason lies in how digital audio and video signals work compared to their analog counterparts.
An analog signal, like those you would get out of RCA cables, takes a media source and converts into an electronic signal that directly represents that source.
With audio, for instance, the voltage of the signal directly translates to how far the speaker cone is pushed from its resting position and the changes in voltage create the motion of the speaker cone. This means more voltage equals louder sound.
Video is a little bit more complicated, but the same basic principles apply. In theory, you can look at the voltage pattern and be able to have a rough idea of what will be displayed.
With digital signals, this is not the case. What this means overall is that if you weaken the strength of an analog signal, there will be a weakening of the resulting output. The sound will be quieter, and you might get some issues regarding the color of the picture.
How HDMI Reduces Signal Loss
With a digital signal, this is not the case. Unlike an analog signal, which communicates not only through the frequency of electrical pulses but also their voltage, a digital signal communicates only through the frequency of electrical pulses. With a digital signal, there are only two states: high and low.
Unlike an analog signal, the information is encoded before being sent through the wire and decoded at the other end. The shape of this signal depends not only on the information being sent but also the encryption protocol between the two devices.
This means you would not be able to immediately tell what is happening with the audio or visual information by looking at the electrical pulse pattern.
Because the digital signal depends only on frequency and not voltage, reduced power does not translate to muffled sound or color-shifted picture. This is why you shouldn’t have to worry about using a passive HDMI splitter for short cable runs.
Longer runs, however, may result in radio interference since they will degrade the sound further, making radio frequency noise take over the signal. If you have this problem you will notice choppy or crackly audio and red and green dots on the screen.
Using an active HDMI splitter for longer cable runs should help eliminate this problem. However, if the problem persists, you may want to upgrade your HDMI cable to one that is better shielded, or another type like directional cables which we’ve talked about before. A shielded cable has an extra layer of material (usually a metal alloy or carbon allotrope) that deflects radio waves.
When you have older equipment, you may be working with fewer HDMI ports than you need. Now that you know about HDMI splitters, that shouldn’t be a problem anymore!