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.).

Things I Like

Overall

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

Sound

With the exception of a big flaw at high sample-rates (see below), 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 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. Physical inputs can be freely mapped to different faders and tracks.

Size

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.

Backlighting

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

Support

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

Ultrasonic Noise!

If you are planning on recording ultrasound at 192k sample-rate, do not buy a MixPre series recorder right now!
Users have noticed a serious problem when recording at high sample-rates on all MixPre recorders: Sometimes bursts of obnoxious ultrasonic noise are injected into the recording! Usually it happens in sync with transients but I also noticed it during an otherwise quiet moment. The spectrum of the noise starts above 20kHz so you shouldn’t hear it at 44.1k/48k sample-rates. (According to their Facebook group, Sound Devices is working on a fix but it’s not obvious whether the solution will require the recorders to be recalled for hardware modification.)

These metal strikes showed no clipping on the meters during recording (and the limiter was on). Those vertical columns are MixPre ultrasonic noise bursts. Ack!

A close-up of two hits.

A recording of metal strikes like the ones shown above, recorded at 192kHz and slowed down to 1/10th speed. The last one is a real mess!

No Pre-Record Feature

This is just dumb. It’s 2018 and most <$300 handheld recorders have been offering a pre-roll buffer for ages. This feature might not help dramatic film/TV shoots, but it’s great for general field-recording where you might want to capture unexpected sounds.

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

Official L-Series sled (top) and my first steps toward a DIY flat battery (bottom)

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.

I’m working on a solution using two flat lithium-ion batteries that will be attached to the top of the recorder, so the footprint remains small and it only gains about 10mm in thickness. I’ll add updates as it develops.

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.