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CCRMA Studio D

CCRMA Studio D (Knoll 221, behind the Classroom - “Downstairs”) is a small (about 15x10.5 foot) general-purpose computer music studio suitable for a variety of activities, primarily designed for composition, mixing and mastering in an 8-channel sound field.

How to links:

Studio D Contents

The front of Studio D with a laptop plugged in

In this space you should see:

Photo of Studio D Audio Rack. See bullet list above for an explanation of the contents.
Studio D Connection Diagram

Don’t touch

Studio D users are expected to leave all of the following alone:

If you see any problems with any of the above please contact CCRMA staff.

To Reset Studio D

Studio D Patch Bay

There is an analog patch bay on the rack, just below the MOTU. As the connection diagram above shows, the patch bay connects the MOTU outputs 1-8 to the Volume8 inputs 1-8. When nothing is connected to the front of the patch bay then the MOTU goes into the Volume8.

Alternately, you can connect your own 1/4” analog audio source (for example, coming from your phone) to the bottom row of the patch bay, connecting that source to the corresponding speaker (via the Volume8 knob).

How to plug an analog source (from a headphone jack) into channels 1+2 of the Studio D sound system via the patch bay.

Selecting Your Laptop or the CCRMA Linux Workstation

Studio D’s KVM switch once looked like this

CCRMA maintains a CCRMA Linux Workstation for any CCRMA user to use. Alternatively, you can use your laptop.

There’s a KVM switch labeled “Linux” (1) or “laptop” (2). Each has a corresponding button (for selecting that source) and yellow LED showing which is selected.

This switch controls access to:

  1. The MOTU 1248 audio interface (that goes via the Volume8 knob and crossovers to the 8.1 speakers).
  2. The USB keyboard (Apple Keyboard with Numeric Keypad: “A1243”)
  3. The USB mouse (Logitech “Click! Optical Mouse”)
  4. The Dell UP2516D (dead Dell link) video monitor (2560x1440, 60 Hz)

Switching the KVM switch is equivalent to suddenly unplugging the MOTU’s USB from one computer and plugging it into the other computer. This is strongly not advised while you are making sound. The studio is designed to let you use either computer, not both at the same time.

Using Your Own Laptop

Connecting Your laptop

A sleeve carrying USB and HDMI cables sits unplugged on the left of the main desk. All the dongles you might need (accommodating Mini DisplayPort and USB-C) are in the drawer under the Volume8 (or check the Adapter Closet if you have special needs).

You can follow any subset of these steps in any order:

Playing Sound from Your Laptop

For stereo you could just use your headphone jack: connect a cable that splits 1/8” stereo to dual 1/4” unbalanced between your headphone jack and the patch bay.

For more channels you need to connect to the MOTU via USB as decribed above.

Using the CCRMA Linux Machine

Select linux on the KVM switch. (The CCRMA Linux Workstation is cmn33 and it should always be plugged into the switch.)

Logging in

You should be able to use your usual CCRMA username and password, and once you log in you should be able to see all your files, like with any CCRMA Linux Machine.

Configuring Linux Audio

Usually it “just works” but may require several attempts to start audio, because of weird behavior with MOTU and Linux. You might want to manually change the MOTU’s sampling rate from the front panel.

If you output stereo via ALSA then you might get a questionable automatic 7.1 mix - instead we recommend JACK.


Audacity should see the MOTU 1248 and offer it as an input and/or output audio device.


You will probably need JACK to use Ardour, Pd, JackTrip, or other software.

The main issue is that you have to make sure JACK is talking to the proper audio device, in this case either 1248 (hw:1) aka hw:D1248 or USB Audio (hw:1,0) aka hw:D1248.0

More info about running JACK on CCRMA Linux Workstations

Note that JACK sees the MOTU as having 24 inputs and 24 outputs, even though in fact we use only the 14 analog inputs and 12 analog outputs. Inputs 15-24 and outputs 13-24 “do nothing”. Almost always we use only outputs 1-8.

Sound system and bass management

Any computer using the MOTU can output (up to) 8 channels, one per speaker.

These 8 signals go through the Volume8 knob (unless something else is connected via the front of the patch bay). The Volume8 provides a master gain control on a single big knob that affects all 8 channels equally.

These 8 whatever-volume-you-like signals go into two Xilica XP-4080 DSP Processors (four into each). The Xilica performs bass management by implementing crossover filters so that 8 highpass signals go to the loudspeakers and a mix of all 8 lowpass signals feeds the subwoofer (actually each XP-4080 outputs a lowpass signal and the two are mixed inside the subwoofer).

MOTU I/O channels

The Studio D MOTU 1248 is configured to be a USB audio interface passing all its analog inputs and outputs to and from your computer. (All digital inputs and outputs are disabled except for the Audio streaming over USB that connects it to your laptop as an audio interface.)

Input channels your computer sees:

Output channels your computer sees:

Note that if you choose the MOTU as your operating system’s selected audio interface, then all the “normal” computer sounds like audio from web browsers will come out channels 1+2 (so you can hear them in speakers 1+2 and/or headphone 1).

Seek staff assistance if you want to use the MOTU’s digital audio I/O (ADAT, S/PDIF, or AVB).

This is how this I/O routing appears in the MOTU’s web-based GUI:

Studio D MOTU 1248 routing configuration per the web-based GUI


Troubleshooting Sound

Are all 8 loudspeakers powered on?

Note that the Genelecs automatically power themselves off after a while; you have to send them a signal to “wake them up” (which also turns on the green front-panel power indicator LED).

Is everything still plugged into the KVM? Should be 2 computers (linux and your laptop), MOTU, shared keyboard, mouse, video monitor

Are all of the Xilica input and output channels unmuted?

Troubleshooting Video


make sure the Linux machine works on the KVM or reboot it.

Try power cycling the KVM

Reseat the video connection(s) to your laptop

Try a different dongle

This page of CCRMA documentation last committed on Thu Apr 27 10:57:34 2023 -0700 by Matthew James Wright. Stanford has a page for Digital Accessibility.