This app note is a short example of recording multichannel audio on Linux using miniDSP devices.

Please note: miniDSP can't provide support for non-miniDSP hardware and software. In particular, we cannot trouble-shoot Linux-related issues. If you get stuck with Linux and miniDSP hardware, try a simple configuration such as the one we describe here and then proceed from there.

What you will need [Top]

For multichannel recording, you will need one of the following USB interfaces:

  • The USBStreamer (or kit version) supports 8-channel ADAT and 8-channel PCM over I2S (with an additional two channels via TOSLINK).

  • The MCHStreamer supports many different formats, including 8-channel ADAT and 8-channel PCM over I2S (optionally with an additional two channels via TOSLINK or SPDIF), PDM and TDM.

  • The USB microphone array series (UMA-8/UMA-8SP/UMA-16) support multichannel audio for custom beamforming algorithm development

  • The U-DIO8 supports 8 channels of input and output via AES/EBU or SPDIF (BNC).
miniDSP USBStreamer   miniDSP U-DIO8

These devices are all USB Audio class-compliant, so will work on Linux without any driver installation required.

In the case of the MCHStreamer and USBStreamer, the correct firmware must be loaded to configure it for the desired I/O format. For example, for ADAT I/O, load the ADAT firmware. See the relevant user manual for the procedure.

Linux setup and DAW installation [Top]

As a concrete example for this app note, we installed Linux Mint, a user-friendly distribution of Linux, on an Intel NUC. Because of the wide variety of Linux systems, you may need to do things a bit differently depending on the Linux distribution you have installed on your own computer.

For multichannel recording, you will also need a DAW (Digital Audio Workstation) application. For this app note, we installed Ardour. Once the installer is downloaded, open and install it. In Mint, for example, double-click on the downloaded file and then click on the Install Package button.

During the installation process, there were a number of options:

  1. We elected to install Jack (although we didn't use it for this app note).
  2. We chose to enable realtime scheduling:
    Enable realtime scheduling for jackd

Create a project [Top]

First make sure that your miniDSP device is connected to your Linux computer via USB. In the case of the U-DIO8, power it on.

To start Ardour, locate it in the main menu in the Sound & Video section. (Your version of Linux may be different.) When Ardour starts, set the parameters as shown here:

Project setup in Ardour

Note that the miniDSP MCHStreamer is automatically detected and can be selected from the dropdown menus for the Input and Output devices.

On the next screen, enter 8 for "Create Tracks," then click OK:

Create 8 tracks in Ardour

Record audio [Top]

Enable all tracks for recording. This screenshot shows the record enable button for one track:

Enable track recording in Ardour

Then press the main record and play buttons, in that order:

Record buttons in Ardour

Ardour will record all 8 input channels from the MCHStreamer, USBStreamer, or U-DIO8. Here's our screen after recording an 8-channel file over ADAT with an MCHStreamer:

8-channel recording with miniDSP MCHStreamer

You can now proceed to mixdown or export to a file. Have fun, and please let us know how you go in our forum!


 

This app note is a short example of playing back stereo audio from a Linux desktop to a miniDSP device.

Please note: miniDSP can't provide support for non-miniDSP hardware and software. In particular, we cannot trouble-shoot Linux-related issues. If you get stuck with Linux and miniDSP hardware, try a simple configuration such as the one we describe here and then proceed from there.

Basic Linux setup [Top]

We'll assume that you already have a computer running Linux. Since there are so many different Linux distributions ("distros"), it's impossible to give instructions that will work for all of them. We chose a user-friendly distro to use as an example and installed Linux Mint on an Intel NUC.

Photo of miniDSP IL-DSP with Intel NUC

The photo above shows our IL-DSP headphone amplifier, which we've used for the screenshots below. However, all miniDSP devices that support audio playback over USB are class-compliant and so will also work with Linux without any need to install drivers:

Note: this app note describes stereo audio playback to a miniDSP device over USB. However, it's not possible to configure a miniDSP audio device using Linux, as our configuration plugins run on Windows and Mac only.

Install a music player[Top]

For high quality music playback, you'll probably want a dedicated music player. For this app note we installed Strawberry. Download the package that matches your version of Linux from the linked page. The current (as of 2019) version of Linux Mint is based on Ubuntu Bionic, so we downloaded the Ubuntu Bionic installer.

Once the installer is downloaded, open and install it. In Mint, for example, just double-click on the downloaded file. You will probably need to install a few additional packages:

Install the Strawberry music player

Configure playback [Top]

Connect your IL-DSP or other miniDSP device to the Linux computer with a USB cable. Start Strawberry (in Linux Mint, go to the main menu at lower left and then the Sound & Video section.) Drop down the Tools menu and select Settings.

  1. Click on Collection and add your folder containing music files:

    Add folders to the Strawberry library
  2. Click on Backend and select the option "Output to a sound card via ALSA." Then select the miniDSP audio device:

    Add folders to the Strawberry library

    Note that we disabled volume control in the player. This is because we use the volume control in the IL-DSP.

Play music [Top]

Navigate the library and double-click on an album to add it to your playlist, then press the Play button.

Strawberry player control buttons

And that's it!

Playing audio from Strawberry to the miniDSP IL-DSP

Have fun, and please let us know how you go in our forum!

Postscript: system-wide audio [Top]

While Strawberry allows you to select an audio device specifically for music playback, you may also want to select your miniDSP device as the default system-wide output for all audio playback. This will vary with the specific version of Linux that you use. On Linux Mint, open the main menu and go to the Preferences section, then select Sound. There you can choose the audio output device, like this:

miniDSP IL-DSP as system-wide audio device on Linux Mint

The miniDSP SHD includes not only Dirac Live® but also a full set of crossover functions on its four output channels. One use of this is as a flexible tool for integrating subwoofers into your system along with Dirac Live. This app note shows you how.

We will assume that you have already installed the SHD plugin and Dirac Live Calibration tool as per the User Manual. If this is your first time using a miniDSP for Dirac Live calibration, we recommend that you perform a calibration first using just the two speakers before attempting to integrate a subwoofer. This will familiarize you with the operation of the software. It will also give you a baseline that you can compare to the system with integrated subwoofer.

Getting connected[Top]

Connect the system as shown in this diagram:

SHD subwoofer integration - system connections

The diagram assumes that you are using one subwoofer. If you are using two subwoofers, connect the second to output 4.

Configuring the plugin[Top]

Start the SHD plugin and click the Connect button. (See the User Manual for more information.)

For clarity, use the Outputs tab to change the displayed labels on the output channels. In the example below, we have used "Left Sp", "Right Sp" and "Sub". Then set up the Routing matrix like this:

SHD subwoofer integration - routing matrix

If you are using two subs, turn on the routing from Dirac 1 and Dirac 2 to to output channel 4.

On the Outputs tab, click on the Xover button for channel 1. Here you will set a high pass filter, to remove low frequencies from the left speaker. Here is a typical example:

SHD subwoofer integration - high pass filter

Do the same for the right speaker (channel 2).

For the subwoofer (channel 3), set a low pass filter to remove high frequencies. Here is a typical example:

SHD subwoofer integration - low pass filter

If you are using two subs, do the same for the second sub connected to channel 4.

You can also set the time delay between the speakers and the sub using the output channels. As a starting point, use the difference in distance of the speakers and the sub to calculate the delay. For example, if the sub is 1 meter further away from the listening position than the speakers, set the delay on the speakers to 2.9 ms:

SHD subwoofer integration - delay on speakers

If the sub is 1 meter closer to the listening position than the speakers, set the delay on the sub to 2.9 ms:

SHD subwoofer integration - delay on sub

Note: subs in rooms are unpredictable. The above is just a starting point. You may need to make further adjustments after measuring (see next section).

Initial Measurement[Top]

We recommend that you perform a measurement to check for initial integration between the subwoofer and the main speakers around the crossover frequency. While Dirac Live will correct for frequency response anomalies, it can't fully correct if you have a large "hole" in the frequency response at the crossover.

You can use Room EQ Wizard (REW) or a similar program to do this measurement. To use REW with the UMIK-1, please refer to our application section on acoustic measurements.

If you don't wish to learn how to use REW, you can use the Dirac Live Calibration Tool to perform this measurement. Save your configuration to a file and quit the SHD plugin first. Then follow the normal calibration procedure described in the SHD User Manual, but only perform a single measurement (instead of the full set of nine) before proceeding to the Filter Design tab. The "before" measurement shows the combined response of the subwoofer and speakers:

SHD subwoofer integration - measurement with DLCT

If there is a large "hole" in the response around the crossover, you will need to make some adjustments and remeasure. Quit DLCT before starting the SHD plugin again. Adding a delay to either the speakers or the subwoofer will change the response, as will inverting the subwoofer. You can also adjust the low pass and high pass crossover frequencies and change the slope. If the subwoofer is much higher or lower in level than the speakers, adjust the gain on the subwoofer.

See the User Manual for information on how to make these adjustments. After making adjustments, quit the plugin, start DLCT, and repeat the measurement.

Run Your Dirac Live Calibration[Top]

You can now proceed to run the full set of nine measurements for the Dirac Live calibration. Adjust the target curve to suit your preference. For example, this screenshot shows a target curve with an elevated bass level, which many people prefer, and the "after" response:

SHD subwoofer integration - after optimization

Advanced multisub integration[Top]

For even better subwoofer integration, two or more subs can be used to reduce the variation in subwoofer frequency response across the listening area. While EQ can correct the response to be flat in one location in the room, it cannot correct for spatial variation. For example, if the level of 40 Hz in one seat is 10 dB different to the level in the next seat, the difference between the two seats will always be 10 dB.

We have an extensive app note on optimizing multiple subwoofer on our site here: Tuning multiple subwoofers with miniDSP.

  • If using two subwoofers, they can be connected directly to the miniDSP SHD (outputs 3 and 4).
  • If using more than two subwoofers, either:
    1. Use Y-connectors to connect two subwoofers to each output of the SHD. This will not give individual control over each sub but can be used to good effect with Methods A and B in the app note linked above.
    2. Use an external DSP such as a 2x4 HD or 2x4 Balanced. Up to four subwoofers can be independently controlled from each external DSP.

When optimizing your multisub setup, be sure to use a preset that does not have a Dirac Live calibration loaded, so that Dirac Live gains and delays are zeroed. When done with optimizing your multisub setup, then a complete Dirac Live calibration.

Wrapping up[Top]

That's it for this app note! Have fun, and please let us know how you go in our forum.

 


This app note shows you how to stream audio over the network to a miniDSP 2x4 HD or DDRC-24 by using a Raspberry Pi Model 3A+.

If you're looking for an all-in-one streamer/DSP/digital preamp solution, check out our SHD Series streamers. In addition to the convenience of an all-in-one solution, these models have higher specifications, more digital inputs, digital outputs, and balanced analog I/O (for the SHD model).

Please note: miniDSP doesn't provide support for hardware and software that aren't miniDSP products. This application note demonstrates the use of miniDSP products together with other products.

What you'll need [Top]

For this app note we will be using the Raspberry Pi Model 3A+. This board is even smaller and cheaper than the popular Model 3B+, but has the same processing power. It has only one USB port and supports Wi-Fi only, no Ethernet. We thought it a good fit for this app note. You can use the Model 3B+ instead if you wish, as all the instructions are the same.*see footnote 1.

Raspberry Pi Model 3A+ on top of miniDSP 2x4 HD or DDRC-24

In addition to the Raspberry Pi 3A+, you will need a 5V power supply with micro-USB connector, a micro SD card, and a case. We used the official case as shown in the photos, but there are lots of choices. If you haven't used a Raspberry Pi before, you may prefer to buy a kit containing these extras together with the board.

You will of course need a miniDSP processor that accepts audio over USB. The miniDSP 2x4 HD and DDRC-24 are perfect candidates for a low-cost DSP-powered streamer, as they are compact and very affordable. These two units are the same hardware but the DDRC-24 has Dirac Live room correction built into it.

Before you proceed, we suggest that you start the 2x4 HD or DDRC-24 plugin (our word for their user interface/control program running on your computer) and make sure that you have selected USB audio input. You can also do this with an infrared remote later on.

Select USB input in the plugin

1. Burn the SD card[Top]

You'll need to download the software that will run on the Raspberry Pi. We'll use the Linux distribution called Volumio for this app note. This is the same base software that we use in our SHD Series streamers. Download it at https://volumio.org/get-started/.

Once you have it, burn it to the micro SD card. A good program for this is Etcher, which runs on Mac, Windows, and Linux. Insert the micro SD card into your computer's card slot or a USB card reader. Select the downloaded image and the card, and click "Flash!"

Warning: make absolutely sure that you have selected the SD card and that the size displayed in Etcher matches the size of your card.

Flash Volumio with Etcher

Take the card out of the slot or card reader and insert it into the Raspberry Pi. It goes in like this (looking at the bottom of the Raspberry Pi):

Insert SD card into the Raspberry Pi Model 3A+

2. Get connected [Top]

To connect the Raspberry Pi to your 2x4 HD or DDRC-24, just connect the USB cable from the Type A port on the Raspberry Pi to the mini Type B port on the miniDSP.

Connect miniDSP 2x4 HD or DDRC-24 to Raspberry Pi Model 3A+ by
USB cable

Now plug in the power to the Raspberry Pi and your miniDSP. You should see the red light on the Raspberry Pi come on and the green light start blinking. Wait a couple of minutes before proceeding to set up Wi-Fi.

3. Set up Wi-Fi [Top]

Use your computer's network manager to search for a wireless hotspot named Volumio. This is started automatically by Volumio when it can't connect to a network. Connect to this hotspot with the password volumio2:

Join the Volumio hotspot

Then open your web browser at http://volumio.local or http://volumio. Run through the startup procedure and select the miniDSP 2x4 HD or DDRC-24 on the third screen:

Select the miniDSP 2x4 HD or DDRC-24 in Volumio setup wizard

Navigate to the Network settings page and locate the Wireless Network Connection section. Select your home network and enter its password, then click Connect. We recommend that you connect Volumio to your home's 5 GHz network if you have one.

Join the home network

After Volumio connects to your home network, the interface will disconnect. Change your computer's network settings back to your home network and reload the Volumio interface. At this point, we recommend that you go back to Volumio's Network page and turn Off the Enable Hotspot setting, as leaving it enabled is a potential security risk.

4. Play music [Top]

For a quick start, go to Browse in the Volumio interface and select Web Radio, then Top 500. Take your pick and play!

Play Web radio to your miniDSP

Web Radio is not high resolution, but there are a lot of music playback capabilities in Volumio that are. Here are some ideas for you to explore:*see footnote 2

  • Go to the My Music page and enter your login details for TIDAL or Qobuz.
  • Look at the Plugins page to enable other services like Spotify and Pandora.
  • If you have a DLNA music server running on your network, locate it from Browse and then Music Servers.
  • If you have music files stored on a network share, add it on the My Music page. *see footnote 3
  • If you are an Apple user, select Volumio as the output device in System Preferences on your Mac or Control Center on an iOS device.

Wrapping up[Top]

That's it for this app note! Have fun, and please let us know how you go in our forum.

Footnotes

  1. If you use a Model 3B+ with Ethernet, you may experience some clicks or pops when streaming high-res audio. This is a consequence of the internal design of the Raspberry Pi and is unrelated to the fact that a miniDSP is connected to it. So even for the 3B+, our recommendation is that you use Wi-Fi. Note: no such Ethernet problems with our SHD Series streamers!

  2. Since the Model 3A+ has only one USB port, you won't be able to plug in a USB stick for music. As shown in the list, however, there are lots of other methods.

  3. If you have a large library on a network share, the Pi might slow down a lot when scanning it. For the sake of a number, consider a library of more than 10,000 tracks "large."


The miniDSP SHD can be used with a Logitech® Harmony® remote. For this app note, we tried two of the most affordable Harmony remotes, the Harmony 650 and the Harmony 350. The Harmony 650 has a small screen and is easier to set up, while the Harmony 350 is a bit cheaper. This short app note shows you how easy it is to set up!

miniDSP SHD with Harmony remote

Note that miniDSP cannot provide support for non-miniDSP products. Please contact Logitech Support if you have an issue with your Harmony remote that is not directly related to a miniDSP product.

To set up the remote, you will need to install the MyHarmony desktop app. (Click on the link for the download page.) When you start this app, you will need to log into your Logitech account, or create one if you don't already have one.

Connect your remote to your computer with the supplied USB cable and start MyHarmony. If you haven't added your Harmony to your account previously, click on the "Add a remote" button:

Add Harmony remote button

Cick on the remote icon and then Devices. Click on the "Add device" button:

Add device to Harmony remote button

Enter "minidsp" and "shd" as shown here and click the Add button:

Search for miniDSP device

And that's it! Your miniDSP SHD has been added:

miniDSP device added to Harmony

If your Harmony remote has a screen, you're all set to go. Volume and mute are mapped to the expected buttons, and you can use the soft buttons around the screen to navigate and control other functions of the SHD. If you wish, you can set up more hard buttons to directly control the SHD. In this example below, we've added preset selection to buttons 1 ‑ 4:

Set up hard buttons to control miniDSP device

With the Harmony 350, you will definitely need to add hard buttons, as there is no screen. The procedure is different to the above, so please refer to the Logitech documentation if you have this remote.

Once you've set up the remote, click on Sync in MyHarmony, then Finish. Disconnect the USB cable and test your remote with the SHD!

Harmony remote screens for miniDSP SHD