written by
Bojan Šernek

How Mix:Analog Racks Analog Gear

1 min read

At mix:analog, we host online sessions with genuine analog gear for users all around the world. Our analog processing fleet has grown many times over the past three years. As a result, we are about to reach 30 pieces of hosted gear and supporting analog infrastructure in just a few weeks from now.

Our Beautiful Studer Tape Machine

When I see cool things on the internet full of exciting and exotic technology, I’m always super interested in any tidbits I can find on how it’s organized and running. For example, projects from artists like “Look Mum No Computer” are great to watch for inspiration and a source of learning about innovative engineering.

It comes as no surprise that we get a lot of questions about our racking setup. How do we automate gear? What converters do we hook them up to? Is there any additional conversion or signal loss when patching/going through chains? How do we handle cooling and powering the gear?

Let’s look into this today.

Gear Automation

When we first get analog gear, it usually comes without automation of any kind. This means that the only way to change the settings is by using our fingers on the front panels. As lovely as it is to get visits, this is impractical if we want to run an online studio! So the first order of business is to analyze the schematics, carefully disconnect the front knobs from the rest of the circuitry and add in our custom-designed automation boards.

These boards use only passive, mastering grade components in the signal path and are comparable in quality to mastering grade volume controllers. This is how we automate knobs and switches, making the controls available over the internet to our users.

Hooking up to Converters

To send audio to the analog gear, we need to hook them up to a digital/analog converter. We never scamp here and use BURL audio converters exclusively. We love the company, its design ethic, the sound of the converters, and its versatility. Hitting them harder makes their presence known (in a good way) but back off a little, and they are eager to hide out of the way, becoming the most transparent, 3D converters.

We use high-quality Klotz cabling, like our friends at Elysia Audio.

Building Chains and Patching

Going direct from converter to analog gear and back is an excellent setup in terms of sonics, but that changes quickly when more than one device is desired in a chain. The standard way to address this is to chain the effects digitally by going in and out of converters however many times it is necessary. However, this is not ideal in terms of sonics. A better solution is to use a patch bay that keeps the signal analog without additional conversion as it travels from analog gear to analog gear.

Solutions in this area are not without problems. Some of these problems are not talked about often. To start with, most patch bays are not automated. The only way to change a chain is to change the cabling physically. The upside, however, is that any active electronics or conversion does not degrade the signal.

While automated patch bays do exist, you have to be careful with the fine print. Is the patchbay blocking or non-blocking? A blocking automated patchbay has a significant possibility to produce a short but audible pop in an existing connection. When some other chain is being established or disconnected. With Mix:analog, many users are using the system simultaneously, so this is not acceptable. Using a blocking patchbay would mean that one user's audio would receive audible pops while another one is working on his chain.

Additionally, some patch bays, even if they are non-blocking, use active electronics in the signal path. How much effect this has on the sound depends on the implementation. Still, it will never achieve the performance and sonic transparency of passive patch bays (like classic non-automated ones with cables).

Most implementation, however, uses low voltage electronics to save cost because components for non-blocking switching exist. Still, they are much too low voltage to work with analog levels (usually they operate at 3 volts while analog gear can swing as much as 48 volts), so the patchbay has to pad the signal down a big deal and then amplify it back. As you can imagine, this implies noise and distortion. Furthermore, this means that the patchbay now has internal headroom, just like any amplifier, and if you exceed it, it will clip.

For these reasons, Mix:analog engineers developed their own automated non-blocking patchbay with a passive signal path. We call these units “Pathfinder,” and we have two deployed already.

Our Elysia Gear

Power delivery and Cooling

Up to until recently, we powered all equipment all the time and distributed power using ordinary home power distributors. But having as much gear as we do comes with certain new challenges and opportunities. For example, since our gear is used 24/7, it gets much more use than ordinarily in a studio that works a single shift. Additionally, audio gear, like all electronics, likes stable, predictable surrounding temperatures and clean, stable power delivery.

In Mid June 2021, we upgraded our power distribution network to improve both. We have deployed eight Netio PowerPDU 4c units across three racks and made sure to include 1U of space between all gear that generates heat.

The PowerPDU 4c are pretty nifty devices - each of them has four power outlets, and they measure voltage and power usage on each of them and can be told to turn any outlet on or off on demand from our code. This means that we can now turn off devices that are not in use, lower the heat footprint, and have less wear on devices.