The miniDSP Flex HTx supports HDMI eARC - enhanced Audio Return Channel - for multichannel audio. Up to eight channels of lossless PCM audio can be sent to the Flex HTx over eARC.
The Flex HTx is backwards compatible with the older ARC standard, although in that case there will be only two channels of audio over HDMI. (The rest of this page will assume eARC is available.)
The HDMI port on the Flex HTx is an output. It must be connected to the eARC-compatible HDMI input port of a modern TV or similar device. The audio goes in the return direction (hence the name). You can not connect an HDMI output from (for example) a computer or blu-ray player to the HDMI port of the Flex HTx.
For multichannel audio, the connected TV must support eARC and not just ARC. In addition, the source device connected to the TV must be able to output audio as multichannel linear PCM, as the Flex HTx can not decode bitstream audio (e.g. Dolby/DTS). Finally, the connected TV must support pass-through of audio from connected source devices to its eARC port.
For information on using HDMI CEC for remote control of the miniDSP Flex HTx, see HDMI CEC.
To use eARC, connect the HDMI port of the Flex HTx to the eARC-compatible HDMI port on the TV.
If your TV does not have an eARC-compatible HDMI input, then you may be able to use an external eARC convertor. See the next section.
Here is a typical connection:
Note that the eARC port on the Flex HTx is an output that connects to the eARC-enabled HDMI input on the TV. The audio goes in the return direction (hence the name). If using a directional HDMI cable (e.g. fibre optic), connect the "Source" end to the Flex HTx and the "Display" end to the TV.
Using an eARC adapter¶
To use a display that does not have eARC – such as a computer monitor, projector or older TV – an external adapter such as those made by HDFury can be used. We have partnered with HDFury to provide a selection of these devices as a bundled purchase with the Flex HTx.
HDFury Arcana 4k or 8k¶
The HDFury Arcana comes in two versions:
The figure below shows how to connect the Arcana with the Flex HTx:
Connect an HDMI source to the HDMI IN port. If there is more than one source, an external HDMI switch is needed.
Connect the display to the HDMI OUT port.
Connect the miniDSP Flex HTx to the eARC OUT port.
The HDFury VRROOM supports 8k video and many other features. It has four HDMI inputs, so an external HDMI switch is usually not needed.
The figure below shows how to connect the VRROOM with the Flex HTx:
Connect HDMI sources to ports HDMI 0 through HDMI 3.
Connect the display to the HDMI TX1 port.
Connect the miniDSP Flex HTx to the eARC AUDIO port.
The connected TV will need to have the correct settings for multichannel audio over eARC. The exact method of configuration and the naming will vary between brands, but the key items to check for are:
Enable HDMI-CEC. CEC stands for "Consumer Electronics Control." It allows HDMI devices to send each other control commands.
Enable eARC. This may not enabled by default, so be sure to locate the setting and enable eARC. You may also need to set the eARC port as the audio destination.
Set the audio mode for external devices to Passthrough. This is so that multichannel PCM from external devices will be forwarded to the Flex HTx over eARC. (The external devices will also need to be set to output multichannel PCM – see the next section.)
Audio sources and formats¶
The Flex HTx only supports linear PCM (LPCM) audio. It does not support encoded bitstream audio e.g. Dolby/DTS. This means that any source device must be capable of generating multichannel LPCM audio. Typically, a setting will need to be changed to tell it to do so.
Unfortunately, not all devices support multichannel LPCM and manufacturers generally do not provide this information in their specifications. We cannot test every piece of hardware but from the limited testing we have been able to do we have these observations:
- Streaming boxes
The Apple TV 4k generates multichannel linear PCM for streaming apps such as Netflix and Prime. With the youtube app, we got multichannel linear PCM with 5.1 audio but not with Atmos. The Amazon Fire devices that we tried were not able to generate multichannel LPCM.
- Blu-ray players
High end players such as Panasonic DP-UB820 and the (discontinued) Oppo players were able to generate multichannel LCPM.
- Gaming consoles
The Nintendo Switch and Sony Playstation 5 were able to generate multichannel LCPM.
If you have a Windows PC connected to your TV, the capability to generate multichannel LCPM depends on the application. We found that we had success with the native Netflix app but not with Prime Video. Browser-based playback does not play multichannel audio.
- TV internal apps
The internal apps on the TV (e.g. streaming apps) may or may not be able to output multichannel LCPM over eARC. Unfortunately, this capability does not seem to be documented in the TV manuals.
The HDMI status screen provides information about the eARC connection: