If your home theater room doubles as a listening room, you may be in the market for an HDMI audio extractor. HDMI audio extractors are also useful to transmit audio from HDMI-only sources to analog-only audio receivers. A small piece of equipment, an HDMI audio extractor is perfect for integrating your home theater into your home audio system or bridging the divide between digital and analog components.
An HDMI audio extractor splits an HDMI input signal into an audio output and a normal HDMI output. While most models only output an analog line-level stereo signal with RCA or 3.5 mm connections, there are models available that output analog 7.1 sound and more.
Using an HDMI audio extractor is fairly straightforward and for the intermediate home audio or home theater user, the install is pretty intuitive. When all is said and done, you can expect to spend around $20-150 plus cables depending on the capabilities of the HDMI audio extractor.
How Does an HDMI Audio Extractor Work?
An HDMI audio extractor must isolate the audio signal from an HDMI signal, then decrypt and recode it into another type of audio signal (usually analog). In all but the rarest circumstances, an HDMI audio extractor is necessary if you intend to convert HDMI to analog audio or any other format.
Because HDMI transmits a digital signal, sending an HDMI output directly to an analog system wouldn’t produce a viable audio (or video) signal. In almost every case, you cannot simply get a cable that appears to convert HDMI to RCA. These cables are designed to work with devices that decrypt the HDMI signal before output.
An HDMI cable is designed with 19 pins that transmit a number of digital signals capable of carrying not only audio and video, but also things like remote control commands and device information. As we’ve said before, there exist directional HDMI cables as well, and they’re a bit better at sending information across long distances.
These signals are HDMI-specific and hence require digital conversion for other formats. For audio, an HDMI audio extractor would be necessary for conversion to other formats.
Why Would You Use an HDMI Audio Extractor?
An HDMI audio extractor makes sense for any instance where you would need to convert HDMI to an audio-only source. Although there are times when an HDMI audio extractor may be your only solution (like when using an analog sound system), in some cases there may be alternative solutions that don’t involve an HDMI audio extractor.
Example of Using an HDMI Audio Extractor
The simplest scenario that involves an HDMI audio extractor is when you have to route audio from an HDMI-only source to an audio-only receiver. If you are an audiophile in addition to being a cinephile, this might apply to you.
If your home theater room doubles as your listening room, you may opt for a secondary stereo system for higher-quality music listening. If you listen to some music from HDMI-only sources (Roku, AppleTV, and other media streamers), you can pipe it to your stereo through an HDMI audio extractor.
A somewhat more cumbersome setup involves connecting HDMI-only components to a system involving an older analog receiver. In such a case, you may want to get an HDMI splitter to route one HDMI signal to your display device and one through your HDMI audio extractor to your receiver.
Of course, you can sidestep some of this if you’d like to mastermind a setup that uses HDMI Audio extraction as well as a wireless HDMI transmitter (more on that here), but for now, we’ll keep focusing on a one-room wired setup.
Does an HDMI Audio Extractor Degrade Sound Quality?
An HDMI audio extractor shouldn’t degrade your audio quality. Because HDMI is a digital signal, it will remain roughly the same quality unless you degrade it via things like HDMI couplers (our explanation). Things that will impact audio quality include the sample rate capabilities of the HDMI audio extractor, the version of HDMI your devices support, the length of the cable used to connect them.
The key factor here is the sample rate. The sample rate is how often a device’s signal is received. The higher the sample rate, the more precisely the intermittent digital signal can emulate a smooth analog signal.
A lower sample rate can mean two things for your sound. First, it means you won’t be able to reproduce higher frequencies (whether your speaker system can broadcast them or your ears can hear them is another story). Second, it means the minor timbres in the sound will be slightly dulled. And if you don’t know what those things mean, then you don’t need to worry about this.
Maximum Sample Rate
Although HDMI has had the same sample rate capabilities since its invention, the HDMI protocol allows for a variety of sample rate specifications that devices can be designed to handle. As such, your sound quality will always be governed by the least capable device in your chain which may or may not be your HDMI audio extractor.
One factor determining this capability is the version of HDMI the devices use. While HDMI has always had a maximum sample rate for single channels of 192 kHz, the aggregate sample rate maximum has increased from 768 kHz with HDMI 1.4 to 1536 kHz with HDMI 2.0.
This means that a manufacturer can theoretically get 8 channels of audio (e.g., 7.1 sound) without a required decline in sample rate per channel (the next step down is 176.4 kHz) to stay within the maximum aggregate sample rate.
Signal Path Length
The other major factor affecting sound quality is cable length, or more precisely, the length of the signal path. This is because, upon connecting, HDMI-capable devices engage in a digital handshake that transmits information that establishes the parameters of the connection between the two devices. One of these things is the sample rate.
Although devices are rated to output a particular sample rate, the length of the cable between them will alter the amount of time it takes for the signal to travel from output to input.
When the devices engage in the handshake, the signal sent between them is timed by the internal clocks of the two devices which determines the sample rate that the two devices communicate at.
Choosing Your HDMI Audio Extractor
The HDMI audio extractor you use doesn’t have to degrade your sound quality. If you pay attention to the specs and don’t do things like needlessly use 25-foot cables when a 4-foot cable would do, you should be able to enjoy high definition sound without any noticeable loss in audio fidelity.
Generally speaking, new HDMI audio extractors should come equipped with HDMI 2.0 or later (the latest version is 2.1 which was released November 2017), so sample rates for 7.1 sound or less shouldn’t be a worry. There are plenty of budget models, like the J-Tech Digitial Premium (on Amazon), which sport 5.1 channel extraction.
Most basic models output only stereo sound, and you will likely have to pony up for a decent 5.1 or 7.1 system (and probably get a unique set of cables to connect all of your components). But Prices for a good 7.1 channel extractor like the Monoprice Blackbird (on Amazon) are still in the double digits, not triple.
There are models that support RCA, 3.5 mm, digital optical, and HDMI. Additionally, there are other pieces of equipment that provide HDMI audio extraction functions in addition to other features such as source and output switching.
When selecting your HDMI audio extraction solution, be sure you have an output format that is compatible with it. RCA and 3.5mm are convertible as analog audio signals. As digital signals, Digital optical and HDMI are not convertible without the hardware to decrypt them.
There are many reasons you might use an HDMI audio extractor. Whatever your application, you should now be better prepared to determine whether an HDMI audio extractor is the appropriate solution for you and how to choose an HDMI audio extractor to suit your needs.
Tuesday 19th of January 2021
Great write up. So I could consider it as a cheap DAC. I am currently running a Chromecast on a cheap led monitor and use the headphone out to send audio to a small stereo receiver. This would probably be better solution.