MOTU 828

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Revision as of 21:17, 17 October 2017 by SteeleNivenson (talk | contribs) (Generating Control Voltage)
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There is a Mark Of The Unicorn (MOTU) 828 mkII digital audio interface. It powers on but takes about 20/30 seconds to warm up. It only has a firewire connection, which rules out connecting to many contemporary computers. It is connected to the computer music workstation.

Specs

Manual

It has some impressive pro audio features circa 2004.

  • 8 mono 1/4" analog audio inputs
  • 8 mono 1/4" analog audio outputs
  • 2 mic preamps with +48v phantom power
  • 2 mono 1/4" analog main output
  • BNC coaxial word clock
  • 96khHz optical in/out
  • S/PDIF RCA in/out
  • SMPTE in/out
  • 5 pin MIDI in/out
  • ADAT DB-9 sync in

Condition

The unit is in good condition. Digital level meters work. I couldn't figure out how to get the S/PDIF or optical ports to do anything interesting, despite the Denon having both RCA and optical inputs. The LCD screen on the unit has a broken backlight. It's almost impossible to see. Unless you shine a light on it.

The Linux driver from ffado is partially broken, in that the patch in the package on Debian testing fails and renders the unit inoperable. It appears that on Debian stable it works okay. Need more testing.

As of Fri Mar 25 09:31:35 UTC 2016 this device went into "xmastree mode". This means the digital level meters began flashing in a regular pattern, all colors. The non-backlit LCD screen displayed some hexadecimal numbers. I think the firmware crashed though the analog components and the software driver continue to work. It also makes noise at periodic intervals without user input. This can be thought of as "fullness" or "unpredictability" or maybe "warmth". I think it's just annoying. Caveat emptor. I discourage recording important things not considered ephemeral with this device.

Driver Reference

MOTU is hostile towards Linux but that didn't stop us!. The preceding code is very interesting in that it exposes what appears to be all the features of the device.

Linux kernel drivers are provided through the ffado project, which exists for Firewire audio. The www says that a nice individual has reverse engineered a MOTU Traveler product, which contains similar chips as all other MOTU firewire products. The company, in this case Mark Of The Unicorn explicitly informed him they have zero interest in Linux drivers, so his work was 100% reverse engineered. Much of the online documentation around tests with this driver and various hardware is offline or a broken link. The wayback machine has some vague references that indicate partial success. Probably best to dual boot before committing to Linux.

A notable improvement with the Linux driver is it allows for arbitrary switching of sample rate through jackd. This means that setting the ADC to 96000 Hz is as simple as selecting the number from a pulldown box. This setting is reflected through the hardware LED so it def works. Now only if the whole unit would work for longer than 15 minutes.

Turns out MOTU has addressed a problem described as "I get high-pitched noise coming out of my 828mkII, how do I factory reset my interface?" This sounds exactly like the problem I was having, though it was exclusive to a reverse engineered driver. original reference via GearSlutz.

WTF Firmware update? Some dude has a .zip file in google docs with some "flash utility". Where did this come from? I assume it was leaked?

"just works" drivers for Windows.

The MOTU Universal Mac Installer works on macOS Sierra! Yea.

Generating Control Voltage

It appears this device is quite interesting in that it can generate CV range signals to drive other modular synths. This means the computer music workstation can also act as a module in a modular analog synth rig. People talk about using it for analog sequencers and off the shelf modular products.

The [sig~] object in Pure Data can output +/- 4.5 V from any of the analog outputs. This DC voltage can be used to control modular synthesizers.

PICS!!11

The following is the Thunderbolt version, which is slightly different than the mkII Motu828.jpg