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miniDSP Flex HTx

 miniDSP Flex HTx front view

 miniDSP Flex HTx rear view

Product Overview

The miniDSP Flex HTx is an eight-channel input, eight-channel output high-resolution audio processor. It features eight channels of analog input and output with both RCA and TRS (balanced) connections, multichannel USB audio input, multichannel linear PCM audio via HDMI eARC, and two stereo digital inputs on SPDIF and optical connectors.


Signals applied to the RCA and TRS (balanced) input connectors are mixed in hardware. That is, RCA input 1 is mixed with balanced input 1, and so on. They are not separately-selectable inputs.

The HDMI eARC feature enables simple integration into modern home theater systems. A single connection to an eARC-enabled television allows up to 7.1 audio from sources connected to the TV.


For multichannel audio over HDMI, the TV must support eARC (and not just the older ARC). Source devices must also be able to output multichannel linear PCM audio. For more information, see the HDMI audio page.

A full suite of miniDSP’s powerful audio processing tools – including bass management – and flexible I/O routing support applications from 5.1 and 7.1 home theatre through to subwoofer integration and active speakers. The optional multichannel Dirac Live upgrade provides world-class room correction.



miniDSP cannot be held responsible for any damage that may result from the improper use or incorrect configuration of this product. Please read this manual carefully to ensure that you fully understand how to operate and use this product, as incorrect use or use beyond the parameters and ways recommended in this manual have the potential to cause damage to your audio system.

Please also note that many of the questions we receive at the technical support department are already answered in this User Manual and in the online application notes on the website. So please take the time to carefully read this user manual and the online technical documentation. And if an issue arises with your unit, please read through the Troubleshooting section first. Thank you for your understanding!


miniDSP Ltd warrants this product to be free from defects in materials and workmanship for a period of one year from the invoice date. Our warranty does not cover failure of the product due to incorrect connection or installation, improper or undocumented use, unauthorized servicing, modification or alteration of the unit in any way, or any usage outside of that recommended in this manual. If in doubt, contact miniDSP prior to use.

Typical applications

The miniDSP Flex HTx is ideal for home theater and multichannel audio systems. In addition to standard 5.1 and 7.1 home theater configurations, its powerful onboard processing and flexible routing support a wide range of applications including active speaker systems and independent control of multiple subwoofers. World-class analog I/O specifications ensure that all configurations perform at a very high level regardless of analog or digital input.


The configuration used must of course fit within the available eight output channels.

7.1 home theater application

Figure 1 shows the miniDSP Flex HTx in a typical 7.1 home theater application. HDMI sources are switched through the connected TV, which in turn sends audio to the Flex HTx via its HDMI eARC (enhanced audio return channel) port.

Typical system configuration of miniDSP Flex HTx with eARC. The optional Dirac Live upgrade adds multichannel (8-channel) room correction.

Figure 1. Typical system configuration of miniDSP Flex HTx with eARC. The optional Dirac Live upgrade adds multichannel (8-channel) room correction.

The analog inputs or USB Audio input can also be connected to a source. For example, the analog inputs may be connected to the (line-level) outputs of an A/V receiver or processor, and the USB input to an HTPC.

Multiple subwoofers

If outputs are unused, they can be used for additional subwoofers. Figure 2 illustrates a modified configuration with three subwoofers connected. There are a number of ways of managing multiple subwoofers; see the app note Tuning multiple subwoofers with miniDSP for an overview and starting point.

5.1 system configuration with miniDSP Flex HTx and multiple subwoofers

Figure 2. 5.1 system configuration with miniDSP Flex HTx and multiple subwoofers

Active speakers

Figure 3 shows the miniDSP Flex HTx used as an active crossover for three, two-way speakers, with two subwoofers integrated. Many other permutations are supported, within the available limit of eight output channels.

miniDSP Flex HTx used in an active system with three two-way speakers (e.g. left, front, center)
and two subwoofers

Figure 3. miniDSP Flex HTx used in an active system with three two-way speakers (e.g. left, front, center) and two subwoofers

Dirac Live room correction


Dirac Live is an optional upgrade. This section applies only if Dirac Live has been purchased and activated. For information on how to upgrade, see Upgrade to Dirac Live.

The miniDSP Flex HTx executes multichannel Dirac Live® digital room correction, from Dirac Research. Dirac Live's mixed-phase filtering technology will improve the imaging of your system, minimize the effects of room modes and resonances, and improve dynamics and clarity.

To accomplish this, the Dirac Live software steps you through the procedure for taking measurements around your listening area. It employs a sophisticated analysis algorithm to make the optimal correction across the whole listening area, not just at a single point. You have full control over the target frequency response. Measurements are taken with the miniDSP UMIK-1 or UMIK-2 calibrated acoustic measurement microphone.

Illustration of Dirac Live magnitude response correction

In addition to correcting magnitude response, Dirac Live® corrects the system's impulse response, which reflects how the system responds to a sharp transient such as a drumbeat. Reflections, diffraction, resonances, misaligned drivers, and so on, all combine to smear out the transient. Impulse response correction is a critical factor for accurate sound-staging, clarity and bass reproduction.

Illustration of Dirac Live impulse response correction


The full specifications are available in the datasheet at the following link: