Sound Devices MixPre-6 Notes

I have been testing the Sound Devices MixPre-6 recorder. This page page will collect my impressions, tips, tricks, etc. This is not an in-depth review. They have been done much more comprehensively by others (see my Recorder Recommendations for comprehensive review links).

This page pertains to the original MixPre, not the updated MixPre-6 II version. It adds 32-bit recording but most of the other characteristics are the same.

Things I Like


It’s the best recorder I’ve used. It’s thoughtfully designed, rugged, upgrade-able, and pretty tiny considering the inputs.


This thing sounds awesome. I do some weird recordings with hydrophones and contact mics so I’m often adding a LOT of gain. It’s clean!

Inputs & Routing

4 XLRs with 48v phantom power + a stereo 3.5mm “aux” jack that can be set to mic (with 3V “plug-in power”) or line. So you can use unbalanced binaural mics, all the way up to ambisonics (requires firmware 3.0 or higher). Some routing is available: Each of the 4 front-panel fader knobs can be assigned to the matching XLR input, or one of the “aux” input channels, or one of the USB inputs when tethered to a computer as an audio interface. (The headphone and USB outputs ar more flexible. Each has a matrix so you can arbitrarily select any tracks.)


The MixPre is smaller than the (cheaper) Zoom F4. This causes problems with batteries (see below) but it’s an overall advantage for me, since I usually record in somewhat casual or stealthy situations. A larger recorder might not get included in an outing due to space & weight.


The MixPre buttons and gain knobs are back-lit with adjustable brightness (a big deal when recording at night or in difficult light).


Sound Devices is a serious company with a longstanding reputation in the field-recording and film sound communities.  They update firmware regularly and they listen to user feedback.


Things I Don’t Like

Upgraded headphone knob, 3D printed by me using the file from LOM.

Headphone Knob

It’s tiny and hard to access, especially when the recorder is in a sound bag. It’s so close to the headphone jack that your fingers can’t wrap around the knob to turn it. The smooth surface doesn’t help. This is important because the knob is also a rotary encoder for menu navigation.

Lucky for us, Jonáš Gruska at LOM Records has designed a knob extender that makes the knob larger and easier to grab. You can order from them or download the .STL file to 3D print it yourself.

Powering Options

My DIY LiPo battery backpack.

Sound Devices has an extensive list of powering options for the MixPre series, but none of them fit my use-case exactly.

  • The included 4x AA battery sled is slim, but you’ll only get 2hrs of runtime.
  • The optional 8xAA sled doubles the runtime, at the expense of size, weight, and the chore of taking out and charging 8 batteries every time. No fun.
  • The optional Sony L-mount (camcorder battery) sled is almost there, but the MixPre is so thin that the batteries have to mount at an awkward 90 degree angle. It’s not too bad if you use two 2200mAh batteries. They last for about 4hrs and they don’t add much thickness to the recorder.
  • You can plug a power bank into the USB-C port, but then you lose the recorder’s battery meter. Sufficient power banks are big, require mounting somewhere, and you’re putting a lot of faith in a flimsy USB connector.

In April 2020 I made a DIY battery backpack using two flat lithium-ion batteries attached to the bottom of the recorder, so the footprint remains small and it only gains about 11mm in thickness.

Basic / Custom / Advanced Modes

The touch-screen menu system is surprisingly navigable, and it has improved with each firmware version. But, the recorder features are governed by a “basic” / “advanced” dichotomy that I find opaque. For example, if you want the 4 front knobs to act as gain controls (for the iso tracks) instead of faders (for the stereo mix) you need to set some menu options to “Custom”, some to “Advanced” and some to “Basic”. There is nothing in the UI that explains what any of this means, and there are bundles of settings that can’t be unbundled. (For example, in my current setup I can’t turn off the limiters because my “gain mode” is set to basic, which was required to get the front knobs to act like input gains.) Why are those two things linked? Why not have a “knob mode” menu entry where we choose between “input gain” and “mix fader”?

Meters Default to Stereo Mix Each Time

You can tap the meters to switch between simple stereo and ISO metering, but you’ll lose the setting each time you turn off the MixPre. Why not have it return to the previous state when powered up? I put in a feature request so hopefully SD will fix this in a future firmware update.

(June 2020) Firmware 7.0 fixed this routing problem:

In firmware version 6.0 (and maybe before?) if you route the 3.5mm Aux input to the virtual faders 5/6 and engage stereo linking, crazy things will happen (live bleedthrough during playback, massive level shifts). Everything is fine if you route the Aux ins to a front-panel fader knob. Sound Devices knows and they will address it in a future update.

(December 2018) Firmware 3.0 fixed my two biggest original complaints:

FIXED: Ultrasonic Noise

For or over a year after the launch of the MixPre series, users noted a serious problem when recording at high sample-rates on all MixPre recorders: Sometimes bursts of obnoxious ultrasonic noise were injected into the recording! Firmware update 3.0 fixed this issue completely, with no compromise in frequency response.

FIXED: No Pre-Record Feature

Firmware 3.0 added a selectable pre-roll buffer. Hooray!