Please Give Me the Power

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This is one of those crossover stories. It’s about audio engineering, but also about reliability engineering. As an IT professional, I have worked with all kinds of electronic equipment, usually stuff that is either in or destined for a data center. And those devices all had one thing in common. Something that can be hard to find in the audio world. Something that does not exist on any of the devices in the photo below.

What do these three devices have in common?

None of them have a power switch. You just plug them in. When they are plugged in, they are on. When they are unplugged, they are off. Obviously they cannot be on if they are not plugged in, but it boggles my mind that they cannot be off when they are plugged in. Here are three unfortunate ramifications to this problem.

  1. Two of the devices above are USB bus-powered interfaces. It feels less dangerous to unplug a USB device, because we are used to it. With the exception of drives that have to be “ejected” properly, you can typically plug and unplug USB and other kinds of devices from your computer at will without worrying about damaging anything. However, the USB interfaces above have audio inputs and outputs that will immediately be “hot” once the power is applied, so it can throw a damaging transient pulse down your signal chain even though it looks like a well-behaved USB device. If you happen to have it connected to some studio monitors, you will know when you apply power because it will produce a loud, damaging-sounding “click.” You can definitely break your speakers doing this. But are you going to unplug the preamp every time you need to switch a cable? No. So you have to find and turn down the appropriate volume or gain settings or even turn off your speakers before powering on or off or changing any cables. It’s an enormous waste of time with the potential to damage the equipment every time you do it. One irony of this is that the studio monitors that are usually connected to these interfaces all have power switches.
  2. The TubePre box is not a USB-powered device; it’s an actual vacuum tube preamp. When you plug it in, power is immediately applied to the analog circuits within, the tubes power up, and signals flow through the interface. I don’t know, maybe I’m old school, but I don’t want to turn on an analog circuit by plugging it in. Especially one with tubes. If the connection doesn’t establish cleanly because there is some momentary physical disruption, it could cause a jitter, or electrical arc, or some other damaging condition. And there are tubes inside. TUBES, people!
  3. If you are like me, you are immediately forced to buy a power distribution unit, or PDU. I’m not talking data center grade here, just a 1U rack unit with a set of power feeds and on/off rocker switches. (I should explain that audio workstations usually have accommodations for rack-mounted gear, which is common in this space.) This allows me to control the preamp, studio monitors, and other gear from one place. There is just one problem—it doesn’t work for the USB-powered devices. So I ended up buying a USB hub that I can connect them all to so that I have one USB connection that powers up all the USB devices. Sigh.

Can we please just start building power switches into audio equipment?

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