How do active HDMI cables work?
Active HDMI cables are a good way to enjoy the full bandwidth of new, high-performance standards like HDMI 2.1, without being stuck to very short cables. Passive HDMI cables have limited maximum lengths
An Active HDMI cable:
- Has an internal processor that modifies the signal
- Draws power from either a separate power supply or the HDMI port of the connected device
- is directional - meaning only one end can be plugged into the display
Active HDMI cables are a good way to enjoy the full bandwidth of new, high-performance standards like HDMI 2.1, without being stuck to very short cables. Passive HDMI cables have limited maximum lengths, while active HDMI cables can go far longer – many times longer than passive alternatives if you use an active optical cable – without losing signal strength or image clarity.
The functional HDMI max length is directly dependent on whether you're using an active or passive HDMI cable.
What is an active HDMI cable?
Traditional passive HDMI cables are merely the HDMI port standard connected to shielded copper wiring. That simplicity makes them great because they can transmit audio and video in either direction – that is where the super handy ARC technology comes in. Unfortunately, thanks to signal attenuation, there is a maximum HDMI cable length, and on newer standards like the HDMI 2.1 cable, it can be quite limited.
Active HDMI cables solve that problem by incorporating signal boosters to amplify the signal from the source and send it further down the line without it degrading. This means that an active HDMI cable can only run in one direction, though, so you need to connect the source end to the source and the destination end to your display. Getting it wrong won't break anything, but you won't get any kind of signal either.
An active HDMI cable can boost a signal by up to three times, making it possible to send older HDMI standards over 100ft in some cases.