A while back I wrote a Sound Devices Mixpre 6 review for The Audio Spotlight. Check it out if you haven’t read it, most of it is still applicable. I have since sold my 6 and replaced it with a 10T, but neither got as much use as my main recorder which is the Sound Devices 633. I primarily got the Mixpres as backups or in case I needed more channels, but after a while I realized that their drawbacks outweighed the advantages so I slowly gave up on them.

For example, on my trips to Gabon and Ethiopia I often required a second rig, but instead of using the Mixpre I plugged the original Mixpre-D into a Sony PCM D100 or M10. This was a bit clunkier than the new Mixpres but far more reliable. At any rate, here’s an update to my original review:

Ultrasonic noise

The biggest issue that I had with the Mixpres is the much dreaded ultrasonic noise problem that has recently been fixed by a firmware update. Sound Devices had acknowledged it on a closed Facebook group but did not otherwise address it for more than a year. Put simply, bursts of ultrasonic noise were injected into recordings by all devices that use Kashmir preamps. Needless to say this makes pitch shifting and proper sound design impossible or very difficult.

Because of this issue I didn’t use my Mixpre for anything important for many months. Besides this, I didn’t really like that SD chose to sweep this under the rug and kept advertising 192kHz recording capabilities. I was expecting them to own up and to offer to buy back the devices. 

Limiters

One other aspect that kept me from using the device is the incredibly poor quality of the limiters. They have a weird release time that results in an obvious pumping effect which renders recordings useless. I couldn’t use the Mixpre for any vehicle or aircraft recording since that’s where I need good limiters like the ones on the 633. Here’s an example of the Mixpre limiters in action:

https://soundcloud.com/georgevlad/mixpre-6-limiter-test

I will mention here that I sent my Mixpre 6 to SD in Berlin because I thought it had faulty limiters. They returned it without fixing and mentioned that it behaved “within parameters”. What’s even weirder is that I heard recordings in which the limiters on other Mixpre 6 devices work as expected. I’m not sure if I was unlucky enough to receive two faulty units (both 6 and 10T) or if quality varies so much between units that both good and rubbish limiters can be encountered.

Poor software

On my trip to Transylvania last year I was joined by a friend who owned a Mixpre 3. Our usual workflow is to leave rigs out overnight for long-form unattended recording. He ended up missing 2 dawn choruses because he had been foolish enough to upgrade firmware just before leaving for the trip. What went wrong? His Mixpre 3 would record up until midnight and then it would simply stop recording because it wasn’t able to create a new file anymore.

Apparently this is a known issue in software development, but obviously SD did not catch it when testing their firmware. As a result, users became involuntary testers and missed important recording opportunities. This is something I’d expect from the likes of Zoom (not because they’re bad, but because they make cheaper units), but not from SD.

Good things?

I’m happy to see more and more people interested in something other than a Zoom h4n for their first field recording kit. The new Mixpre line (along with the Zoom F series) have certainly facilitated that, and that’s a good thing in my opinion. They’ve also helped drive down the prices for used 7-series recorders and old Mixpre D mixers which is great.

Do I recommend getting a Mixpre? Sadly, no. In most cases, you’ll be better off getting a Zoom F4 or F8n, or better even a 6 or 7 series if you can afford it. The Kashmir preamps on the Mixpre might sound marginally better, but the Zoom makes up for it with proper outputs, better ergonomics and most importantly, reliability.

Of course, the positive aspects that I mentioned in my original review still stand. The best advice I can give you is to hire or borrow a piece of kit before you decide to purchase it. This way you’ll know if it’s something you want to invest a good chunk of money in. Hope this helps. If you still have questions feel free to email me using the contact form on the website: https://mindful-audio.com/contact.