I recently picked up a Sound Devices MixPre-3 to use for all my audio mixing and recording needs. Whilst I love almost everything about the device, the power options are a bit complicated. You can use the included AA battery sled and 4xAA batteries, but if you want to power it using a mains power supply you have to use the USB-C port. On the face of it, this seems to open up many possibilities, but it turns out that unless you have a very specific USB-C supply, the mixer will operate in low power mode which disables the USB-A port, as well as phantom power on the 3rd channel (maybe a few other things too). In low power mode, the power plug symbol on the screen is orange instead of green.

From Sound Devices:

To fully power the MixPre-3 or MixPre-6 from a USB power source not listed above, you will need BOTH of the following:

  1. USB-C power source that is compliant with the USB powering specification and is able to output 7.5W
  2. USB-C cable that incorporates the correct pull-up resistors to identify itself as able to provide 7.5W

In other words, many USB supplies are powerful enough, but they don’t identify themselves correctly to the device in order for the MixPre-3 or MixPre-6 to know what’s going on.

Mains Power for MixPre-3 and MixPre-6

When I picked up my MixPre I did enquire about the official Sound Devices MX-Charge power supply but as with all SD accessories, it was overpriced and also a lot bulkier than other USB power supplies on the market. I knew I could find a better option. I tried a selection of USB sources from devices I already had, but they would only power it in low power mode, so I jumped on Amazon and ordered the Anker Quick Charge 3.0 and USB Type-C 24W USB Wall Charger.

I can confirm that this charger does correctly power the MixPre-3 and MixPre-6 via USB-C in full power mode! It is cheaper than the Sound Devices power supply, it feels like it is better constructed (I Love Anker products already and own many), it’s also much smaller and it has foldable pins on it.

Not only that, but should you need to use a longer USB-C cable, you can simply buy a longer one and plug it in, rather than being limited in length as you are with the official SD USB-C supply. There is simply no reason to buy the Sound Devices supply!

MixPre II Owners Note

This post was written when I bought the original version of the MixPre which did not come with a power supply in the box. When Sound Devices released the MixPre-3 II and MixPre-6 II, they also began to include the MX-Charge power supply in the box with the mixer.

Of course, this somewhat solves the original problem that I and many others faced with the original versions of these mixers, but I will still underline two things: The MX-Charge is a cheap-feeling power supply that gives me zero confidence in its ability to last. It also has a fixed cable. I personally think that even if you own an II-series MixPre, you should still consider using a higher quality charger that allows you to use different cable lengths.

USB-C Battery Power for MixPre-3 and MixPre-6

If you want to use a portable USB-C battery pack with the MixPre-3 or MixPre-6, you should order the Anker PowerCore Essential 20000 PD. This is also confirmed to run the MixPre devices in full power mode, and you’ll get much longer battery life than using the AA battery sled.

Hopefully, that’s useful information for a few people! I’m certainly glad I got it figured out. These Anker chargers with the MixPre-3 make a very compact audio package.

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