Single Knob Filter [Project Page]
SKF-VST at Google Code [Source, VST Download]

It’s apparently a big improvement on an Ableton forum solution that used 127 different filter instances in a rack.

I’m aware of the goodness of Single Knob Filter thanks to the Aurora open source DJ mixer project (see yesterday’s write-up); they assign an instance of the plug-in on each of the Aurora’s two mixer channels. Aurora’s Matt originally had the SKF plug-in in their Ableton template, but I encouraged them to replace it with Ableton’s Auto Filter for cross-platform compatibility and ease. That said, for plain DJ filtering, this it the One True Knob.

Now, go forth and use it on some crazy experimental noise soundscape you’ve been working on, just to spite cliche.

Not happy with what you can get off the shelf? Build your own. That’s increasingly the philosophy of people working on music hardware. But a second economy is growing around these unique, boutique projects. By open-sourcing the designs, they offer the opportunity to build upon their work, buying something from a small group of designer-musicians and then modifying it to your purposes. The latest addition is the Aurora, which just became available for sale this week. CDM got an exclusive hands-on look at the new hardware and a chat with one of its designers. Here’s our first look at open source hardware’s newest musical gadget.

The Aurora is called a DJ “mixer,” but it’s really a control surface. It connects via a USB jack for power and to transmit serial-over-USB data, then uses free software to translate that data to MIDI messages for use with software like Ableton Live. The project is the work of a three person team, with Matt Aldrich designing electronics, Mike Garbus designing firmware, and Maro Sciacchitano working on the form factor and look and feel. They have an impressive background in making stuff. I got to hang out with Matt in Boston, where he’s joined MIT’s Media Lab Responsive Environments group, so I expect more good projects out of him soon. Matt and I talked frankly over coffee and pastries about the strong suits, weak spots, and future of the device and other projects.

Kit Availability and Pricing

Availability of the first aurora224 model was announced today:

• Complete unit: This kit requires only basic assembly. The PCB is pre-assembled, as are top and bottom panels, and all parts are included. Basically, you just put those panels, boards, knobs, and button caps together using a hex screwdriver — no soldering required. US$340.00. ($420 international)
• DIY kit: This is the one with all the soldering — not recommended if you’re new to soldering, as there’s some tricky stuff in there. US$270. ($350 international.)

Aurora Mixer Project Site
Order Page
Previously: Aurora: Gorgeous, Open Source DJ-Style USB Controller; Details from the Creators

You don’t get that much of a price break via the kit, so I expect you’ll only want to do that if you really enjoy the smell of solder as much as I do.

Onto the hardware itself:

Hardware

The Aurora is configured with DJs in mind, though it could also serve as a nice control surface for DJ-style mixing for laptop musicians, or as a controller for visuals. (I like the two-channel layout for visuals, so I’m quite eager to work on that.) Unlike something like Livid’s Ohm, it has mixing functions only, not triggers of any kind — but that could make it an ideal companion to a Korg kontrolPAD or (in the open-source spirit) Monome.

The controllers:

• A/B crossfader, with two channel faders (ideal for 2-channel mixing)
• 24 backlit knobs (ideal for EQ, effects)
• 8 backlit buttons (could be used to switch on and off effects or for other purposes)

The controller layout is likely to be the real draw for some. What’s especially nice is the spacing of knobs, which never feels too cramped. For people who like lots of effects control and simple two-channel mixing, it’s about perfect.

It’s important to note what’s missing: the unit doesn’t come with any caps for the faders and cross-faders. I think you’ll certainly want some, which may mean sourcing extra parts from a DJ maker or fashioning your own. Of course, part of what makes these projects interesting is customizing them, so if anyone has good ideas for unique fader caps, I’d love to hear them. Unless you enjoy the feeling of somewhat sharp bare metal, though, this is something you’re likely to want to address pretty quickly.

Form Factor and Lighting

The other aspect of the Aurora’s design that gives it less of a finished feel — though it looks fantastic — is the fact that the case isn’t fully enclosed. The top plate and bottom plate are both beautiful, and it’s lovely actually seeing a bit of the PCB. But that means the USB connector is a bit exposed, and the PCB and bottom plate are open to dust and the like. It’s very, very pretty, but you’ll need a way of enclosing this for transporting it around. I got to talk to Matt a bit about that; we didn’t come up with any perfect solution, but there are plenty of possibilities for those who want to come up with their own enclosure ideas. Ideally, you’d stick with the clear plexiglass-style solution as that’d keep the look right, but it is likely to be expensive to get that made to these specs.

Part of the reason for the clear baseplate and design is to allow the LEDs to show off nicely. In a darkened room, they look really fantastic. The LEDs on the base are pretty simple — just one red, green, and blue LED — but they’re adjustable, and bright enough that when bouncing on the base they do provide a nice effect. There are also dim color bands around the knobs. You can control the LED lighting in sync to music using the included software patches.

Note that these pictures (and Aurora’s video) are of the prototype, which featured engraved labels. I quite like those, but to keep costs down, the shipping units use silk screening. Haven’t seen those results yet, but I’m promised they look good, too. I’ll post a photo if we can get one.

Bundled Software

Like many DIY microcontroller projects, the Aurora communicates with a computer using serial over USB — that is, it doesn’t behave like a normal USB device. It plus in via USB and receives power over the USB bus. But you need special drivers to make it work on Mac, Windows, and Linux, which work by allowing your computer to see it as a serial device even though few computers today (and no Macs) have actual physical serial ports.

For a sense of the setup, have a look at the Windows and Mac setup guide. The most important ingredient is the virtual COM port drivers from the chip maker, FTDI:

Virtual COM Port Driver Page

For Windows Vista, I installed the “setup executable” option 2.04.06 at the top of the list; for Mac OS X Intel I downloaded the special Mac 2.2.10 driver. That works perfectly; on Windows, for instance, the Aurora installed like any other hardware and showed up as COM7. (This process should be familiar to anyone who uses the Arduino; the Aurora is not based on the Arduino but uses the same virtual serial setup.) I haven’t tried Linux, but there are Linux drivers available and the process is fairly similar. (Linux users could also use the available Pd patches.)

If you’re handy with patching or coding, you might be done at this point — you can fire up Processing (cdmo tag | cdmu tag) and talk to it using the serial library. (I’m going to try working on a serial library for the Aurora; stay tuned.)

But, of course, since that will only be a minority of you, the Aurora team have created some software that’s intended to be relatively friendly. The software receives incoming serial data and sends MIDI messages to your software of choice. That means you need a way of routing MIDI between applications — think MIDI-Yoke on Windows or the built-in IAC bus on Mac OS X. (I think I helped out the developers a bit on how to use the IAC bus, because those instructions are now included in the docs!) Once you can do that, though, you can use the Aurora just as you would any other MIDI controller.

There’s an added feature, as well. Using ReWire, the Aurora can add some tempo-synced lighting effects by receiving tempo information from your software. So, for instance, you could fire up Ableton Live and have custom, flashing lighting in time to your music. I would be even happier to do this with just MIDI clock rather than ReWire, as I don’t think the timing is quite critical enough to necessitate ReWire; I hope to have a patch that does MIDI clock soon.

The software is all built in Max 5, but it’s compiled for Windows and Mac so you don’t need to own Max 5 to use it. There are also Pd patches, which keeps your software open-source — it’s worth downloading the free Pd-extended for your OS of choice to play with them. And if you do own Max 5, the Max patches are editable, as well. That naturally means you could also directly interface the Aurora with your Max or Pd patches for controlling stuff you’ve built.

Using it with Ableton Live

I was curious to learn more about how the Aurora team actually make use of this device. After all, often the best creations are the ones designers build for themselves, not for anyone else. Matt showed me a basic 2-channel Live setup, pre-mapped to the Aurora. I convinced him to release that set as a template, so it’s now downloadable in the files section of the Aurora site. You can see how they’re making use of it: two channels, EQ, effects. If that’s your preferred mapping, you can even make use of this template directly. Of course, it’d be equally as possible to customize it or make assignments for software like Traktor, FL Studio, or whatever you want. (I’m going to give mappings for Kore a try for our Kore minisite, which will be an excuse to create a “DJ” rack for Kore.)

You may need to adjust the template to properly receive data.

Here’s a video from the Aurora crew of the results in action:

aurora Open Source DJ Mixer\MIDI Hardware w/ Ableton Live from mcubed on Vimeo.

Impressions

The Aurora really is something special; you can tell that it’s not the typical store-bought controller and people do respond very well to it. Also, while there are control surfaces with cross-faders like Novation’s adorable Nocturn, I can’t think of anything (amazingly) with this particular, balanced layout of effects controls and two-channel mixing. And it really is open source: the enclosure specs, schematics, firmware, and computer software are all available for editing.

It’s important to acknowledge that the Aurora was built as a DJ control surface, and built for MIDI. Messages transmitted over the USB port are all MIDI-formatted, so what this isn’t is a blank-slate control surface using OpenSoundControl like the Monome. It’s really MIDI first.

Those things said, I think it’s worth noting both the Aurora’s strong and weak suits, having played with it for a couple of weeks.

Strengths:

Put simply, this is a very nice controller layout. People who want it are likely to be attracted to the Aurora; people who don’t will obviously move on. The difference is, as an open, DIY project, instead of that decision being made by a large manufacturer, it was made by a group of tinkerers who have opened up the fruits of their laborers to the music community.

The open source nature should make it possible for those in the know to do unusual things, like add a tilt sensor or other things that wouldn’t be possible with a store-bought unit.

The Aurora looks gorgeous and unique, and I really love the exposed design aesthetically — if you can find a way to safely enclose the case.

The controls feel great, too — the knobs aren’t anything particularly special, but the buttons are wonderful and the tension on the faders in particular is nicely tuned. That is, if you can add caps.

Caveats

The biggest caveats have to do with MIDI and serial. By using MIDI, the Aurora doesn’t differentiate itself much from existing commercial MIDI controllers – and making matters worse, you will have to deal with an additional piece of software to route that MIDI into your computer. The arrangement works, but it’s slightly less convenient than having real MIDI drivers. It would be nice, given the need for software between the hardware and your software anyway, if the Aurora used something like OSC and translated that to MIDI. That’s something we might see on future projects.

The other issue is the fact that the form factor isn’t really quite finished. The case is exposed, and you don’t get caps for your faders. That might be a deal breaker, except that with this kind of hardware, you almost don’t want a finished product — the fun is in finding ways to customize the unit. But by the same token, I wish the design made this a bit easier. There’s almost no clearance on the edges of the faceplate or around the screws, and the lovely-looking curved edges would be hard to work into a design. My guess is that you’d sort of build a clear box around the thing. I’m interested in the problem, so I’ll be investigating and asking around some people I know who have worked on these kind of projects — and we certainly welcome your feedback.

Lastly, though it’s a niggling point, I’m not in love with the knobs, I think partly because I’ve been spoiled by the amazing encoders used on Native Instruments’ Kore controller. I don’t mind the lack of EQ center indents, because I can’t imagine using them that way, but that may also be a small drawback for DJs.

Open DJ

The image above sums up what makes the Aurora different from other controllers — and what outweighs some of its current weak spots. Courtesy the Aurora Mixer project.

Despite these weak points, it’s a really remarkable piece of hardware, and one you can get right now and immediately open up and reprogram / repair / rework if you wish. The real test will be to see how people respond to its open-source design, whether that translates into people using it creating some of their own solutions to housing, customization, and software operation in the way they have with some other open projects.

In other words, Aurora isn’t perfect — but that’s actually kind of terrific, because it’s something more important: open.

And I have to point out, the price is very appealing. I really do hope this is the beginning of more open source hardware to come. The key to me will be establishing strong platforms for development (Arduino is a start, as are microcontrollers like the PIC18LF4525 used here) and better models for fabrication, enclosures, and distribution that help keep costs down and (ideally, to support people doing development work) bigger margins.

Bottom line: it can’t be understated that this not only a unique controller, it’s a controller you’d have no problems taking apart physically or in terms of software to change something. And that’s a very exciting thing, indeed.

Would I buy one? As far as DJ-style controllers go, absolutely — this would be on the top of my list.

Stay tuned for more specific hands-on, and let us know if you decide to pick one up. A big thanks to Matt and the Aurora team for sharing the project with me prior to launch and for responding to feedback!

All photos by Peter Kirn/(CC) Create Digital Media unless otherwise noted.

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The Aurora 224 is a DJ-style controller geared for software like Ableton Live. The design is, as you can see, gorgeous: not only is it at the high end of aesthetics in open gear, but it celebrates its DIY nature by exposing the circuit board. It’s USB powered, and offers easy mixing control functions in a 2-channel, DJ-oriented layout. And it lights up and makes pretty colors.

Hack a Day broke the story –

Aurora open source hardware mixer

– but to be clear, it’s not actually a mixer; that is, it doesn’t mix audio signal. It’s just a controller in a mixer layout; any mixing and DJ functions are provided by your software. But it is freely-licensed from the ground up, under a Creative Commons license. (We’ve been seeing CC more and more in music projects, as opposed to the narrower and more programmer-oriented GPL and other licenses. There’s no word yet on which CC license applies to this project, whether it has non-commercial or ShareAlike restrictions, etc.; I’ll post an update soon. See discussion on the Virtual Turntable blog.)

A video with Ableton Live, plus CDM chats with the creators about more details:

aurora Open Source DJ Mixer\MIDI Hardware w/ Ableton Live from aurora mixer on Vimeo.

Project description:

aurora is an open source USB midi controller with user controlled ambient RGB illumination. It combines a standard DJ mixer with 18 effects knobs and 6 toggle switches in a form factor of only 7 x 10 inches. We envision the device as an alternative to bulkier, less affordable, less ergonomic commerical MIDI devices. Currently, many commerical controllers are designed with a wide range of applications in mind. For aurora, we wanted to return to the basics.

Many of us have asked for a controller with "two channels and and a cross fader." These familiar features are included, along with additional knobs and buttons for enhanced control. We believe this arrangement enhances the artist’s creativity and allows for greater control of the software. Using aurora with Ableton Live is a great example of this. Artists have already embraced digital audio and laptop performance. The mixer is designed to be portable. It easily fits in a backpack with your laptop and sound card.

We believe in open source. aurora is designed with this in mind, so essentially anyone can participate in writing firmware or software, or even create their own hardware. In fact, we encourage it, and hope to create a community of users that support this device.

For a technical discussion of the project, we have included a white paper on the website.

Aurora is Matt Aldrich, Mike Garbus and Maro Sciacchitano. They all currently reside in the DC metro area.

The Aurora Team tells CDM a bit more about the thinking behind the license and pricing (which is currently waiting on gauging interest):

We intended for this to be publicly available and 100% open source, so that anyone can build their own device at any time, exactly how they want. All content falls under the Creative Commons License The amount of interest in this project has been incredible. Regarding sourcing, we are waiting on quotes from a contract manufacturer and we will determine the cost of sourcing a fully assembled and tested controller. We expect to have the numbers Thursday and will hopefully announce the price that day. We are also exploring a simple kit that consists of a PCB and two programmed PICs for the guys who love soldering.

So got that? If you’re interested, drop them a line by Thursday! We’ll follow up with the response, pricing, and other details, and hopefully a full-on interview – if you have questions you want answered, ask them here and I’ll pass them along.

I love the idea of a simple kit; I hope they do that.

aurora mixer project site

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