Interfacing Max and Your Eurorack: Expert Sleepers

As I mentioned at the conclusion of my LFO tutorial series, I’m starting work on a set of tutorial articles that focus on using Max alongside Eurorack modular systems. Along the way, I’ve been talking with friends and acquaintances in the Max user community, many of whom are using the ability of their interfaces to output DC-coupled voltages as a way of sending control information to their analog racks - I’ll be talking about this in the first of the analog synth tutorials, so stay tuned. I have been a little surprised to discover that a number of my friends aren’t well acquainted with what seems to me to be the simplest solution out there: The Expert Sleepers interface modules (and plug-ins). Since we customarily spend the first week of the month looking at hardware in the newsletter, I thought I’d give you a quick rundown on something that’s pretty straight-ahead and streamlined and works for me: a pair of Expert Sleepers Eurorack modules and a nifty little interface.

For output to my rack, I picked up an Expert Sleepers ES-3 module, which gives me 8 separate CV outputs via ADAT Lightpipe.

One of the reasons for going with the Expert Sleeper modules is that I want something that my DC-coupled output on my interface won’t give me – bidirectional connections. For that, I added an ES-6 module – it’s the counterpart of the ES-3, providing 6 inputs to my computer via a second ADAT cable. Yes, you read that right – 6 inputs rather than 8. If you’ve gotta have those extra two channels, you’ll need to add an ES-7 module as an expansion. I don’t really need the extra channels. Yet.

In case you’re wondering about clock signals and synchronization, The ES-6 derives its clock signals by virtue of being cabled to the ES-3. The ES-3, in turn, derives its clock signals from its lightpipe input. You connect the cable that comes with the ES-6 up when you install it in the rack, and that’s it. You’re off to the races.

When it comes to a lightpipe (ADAT/Toslink) interface, you may already have what you need if your audio interface is equipped with lightpipe input/output. My older MOTU Ultralite interface doesn’t, so I decided to go with a smaller and lighter solution – a USBStreamer B MiniDSP interface. It’s a straight-ahead piece of kit: a USB input and an input/output pair – one for the ES-3 and one for the ES-6.

Your mileage may vary on this input choice - since I’m often monitoring the analog synth output straight into the board in the studio anyway, I didn’t really need audio from the interface. Another solution would be to go with the Expert Sleepers ES-4 SPDIF/CV interface for output combined with ES-7 expansion modules to provide CV input pairs.

If you’re using it on a Mac, the miniDSP interface is easy-peasy-lemon-squeezy in terms of setup: Plug it in, watch the white LED next to the USB connector light up, fire Max up, drop a [dac~ 1 2 3 4 5 6 7 8] and/or an [adc~ 1 2 3 4 5 6] object into your patch, double-click to bring up the Audio Status, select USBStreamer as the output/input source, and start patching.

If you’re using a Windows system, there’s an ASIO driver available from the manufacturer. When I ordered mine, they helpfully included the necessary download information as part of my order.

The tutorials I’m working on are all about rolling your own when it comes to things to do with input and output, but I’d be remiss if I didn’t mention that the Expert Sleepers also offer their own solution for software control: their collection of Silent Way plug-ins. They’re a de facto standard for Live users, but Max users can also benefit from hosting the plug-ins (AU or VST) via the vst~ object.

In total, there are 18 or so Silent Way plug-ins, some of which are intended to support specific Expert Sleepers modules (e.g. The AC Encoder works alongside the ES-1 module and removes the need for a DC coupled audio interface), and some of which produce control voltages you can use with your rig. You'll find a great in-depth description and look at the set of modules here. It's a great collection of tools, and an interesting thought experiement for the Max programmer - you could begin to imagine Eurorack control possibilities by taking a look around and asking yourself what's not there from your point of view!

I'll have more to say about all this later, so stay tuned - and happy patching!