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A fully-extensible software-based dedicated mixing console emulation. This page is mainly a sketch book for putting such a system together. For the most up to date user interface documentation go here


What do we want to do when we get to the Studio that houses the OpenMixer system:

  • login to the studio workstation, press a button in the UI that says "Workstation" and have all 24 channels of the soundcard connected to all 24 speakers, control overall volume with a fader labeled "Master"
  • walk to the dvd player, insert a DVD disk, press a button in the UI that says "DVD" and have the DVD play in 5.1, control overall volume with a fader labeled "Master"
  • connect a laptop for stereo playback by connecting to a 1/8" plug, press a button in the UI that says "Laptop" and have stereo playback properly routed, control overall volume with a fader labeled "Master"
  • connect a laptop for 8 channel playback by connecting multiple outputs to 1/4" plugs, press a button in the UI that says "Laptop8" and have 8 channels routed to the mid 8 channel speaker ring, control overall volume with a fader labeled "Master"


The OpenMixer software runs in a dedicated fanless computer. Zalman has discontinued their TNN300 and TNN500AF products so we have to look for other options.

Host Computer

Options for fanless computers:

Question: should a second 1Gb/s ethernet be a requirement? It would enable a local audio only subnet for jacktrip without any other packets interfering with the audio streams.

TNN500 case


TNN300 case

Discontinued but still available so it is an option. Advantages: a product we know and works very well. Disadvantages: 70W max power for the CPU so no quad core options, form factor could be smaller (we need something "hidden").

mCubed case

Review of a computer using the same case:

Logisys computers

Other fanless small computers

Audio Interface


  • Outputs
    • 24 analog outputs (speakers - currently 16 used)
    • 24 digital channels (3 x ADAT) to send to computers, etc
  • Inputs
    • 6 analog inputs channels for dvd or blueray/dvd player
    • 8 analog inputs for external analog sources (laptop, etc)
    • 8 analog microphone inputs through an ADAT pipe
    • 24 digital inputs (3 x ADAT pipes) for main computer
    • 16 digital inputs (2 x ADAT pipes) for external computer (laptop, etc)


The audio input and output is controlled by an RME HDSP Madi PCI card ( which provides 64 inputs, 64 outputs, MIDI i/o, work clock i/o, etc. It uses up 2 back panel slots but is inserted into one PCI slot. Another option is the RME PCIe Madi PCI Express card ( PCI Express card (same capabilities, different bus).

Solid State Logic interfaces

Alpha-Link MADI AX ($3745 @ Sweetwater, Alpha-Link/index.asp)

  • 24 analog i/o
  • 3 x ADAT i/o

So, we are missing 2x ADAT i/o plus mic preamps

We could use a second RME HDSP card in the mixing computer (with a Digiface we get 3 x ADAT i/o). That would need a TNN300 case to have all the required expansion slots.


  • 8 x ADAT i/o

We need (extra):

  • 3 ADAT outs to 24 channel analog out
  • 2 ADAT ins from 16 channel analog in (line level)
  • 1 ADAT in from 8 channel analog in (mic level)


  • 2 ADAT ins

The MADI output is split into ADAT outputs using the RME ADI-648 ADAT/MADI converter ( (we get 8 ADAT pipes from it). The ADAT pipes can be connected directly to other computers or equipment, or go through ADAT D/A and/or A/D converters to connect to analog equipment.

Control Surface

The simplest alternative is to use a USB (MIDI through USB) fader box. The Behringer BCF-2000 ( is an inexpensive 8 fader box that could be used as the basic control interface. The Behringer BCR-2000 ( can be used as an auxilliary control interface to do channel assignments. All the interaction between the user and OpenMixer would happen through that interface.


The OpenMixer computer boots into the control program. At least in the first stage it does not even have a monitor, keyboard and mouse for user interaction (just the control surfaces outlined above).

The software would consist of several separate processes that can be started from runlevel 3 (or runlevel 5 is a GUI and X are used).

  • control program
  • jackmp server
  • jacktrip server