Sound Devices MixPre vs 633: Which Recorder to Hire?

What's the difference between the Sound Devices MixPre and the 633?

The MixPre 6 II is a compact field recorder built around 32 bit float. The 633 is a field mixer recorder built for mixing on the move, with faders, limiters and dual card recording. Both use clean Sound Devices preamps, so the biggest difference is how they work on set.

Here's where they actually differ:

• Recording. The MixPre 6 II records 32 bit float, so a shout or a sudden jump in level can be recovered in post instead of clipping. The 633 records 24 bit, so it leans on its limiting: limiters on all six inputs and the outputs. The MixPre 6 II has adjustable limiters on its preamps too, but with float they're a backup rather than the main protection.
• Controls. The 633 has three full size faders on the front and a layout made for people who mix as they record.
• Backup. The 633 records to SD and CF cards at the same time, so you walk off set with a backup already in the bag. The MixPre 6 II records to SD and can back up to a USB thumb drive.
• Inputs. Both take six inputs. The MixPre 6 II has four Kashmir preamps and covers a boom, a couple of radios and a stereo return. The 633 runs a boom, radios, camera links and timecode from one bag.
• Timecode. The 633 has timecode built in. The MixPre 6 II has an internal timecode generator and also takes external timecode from a Tentacle Sync E.
• Size. The MixPre 6 II is small enough to sit on a camera. The 633 is compact for what it does, but it's heavier, which you'll feel over a long day.

One recordist who owns both found the MixPre II series on par with the 633 for sound quality, though the 633 is far heavier and it's still his main recorder. That matches how we use them.

[CONFIRM WITH MIKE: when he'd pick the 633 over the MixPre 6 II on a job, and why]

When should you hire the MixPre 6 II?

Hire the MixPre 6 II for run and gun, documentary, interviews and short films, especially when the talent is unpredictable and you can't ride the levels.

It's for anyone who's ever been burnt by clipped audio. The 32 bit float recording is the safety net for fast shoots, and the four very low noise Kashmir preamps bring through quiet voices, subtle atmos and detailed dialogue. It runs on portable power or mains and it's small enough to sit on a camera or hang off your shoulder all day.

No bag is included, so add an Orca OR270 when you book if you want it ready to wear.

When should you hire the Sound Devices 633?

Hire the 633 for drama, documentary, reality and branded jobs where you need a serious bag rig without stepping up to a cart.

For a proper production sound job, this is where the bag starts. It's compact and tough, with six inputs, three full size faders, limiters on every channel and preamps that stay clean when the talent goes from a whisper to a shout. The layout makes sense the first time you pick it up, which is what matters at 6am on day one. Boom on one channel, radios, camera links and timecode. Done.

It's the recorder in our Premium Location Sound Recording Kit A, with Lectrosonics wireless and an MKH 416 in one case. On our own crewed jobs, our standard kit is built around the Sound Devices 833.

What about the MixPre 3?

The MixPre 3 is the smallest option, for jobs where three inputs are enough. Our MixPre 3 records 24 bit, not 32 bit float.

Field recorder hire for a small crew shouldn't mean lugging a mixer you only use a tiny bit of. The MixPre 3 has three Kashmir preamps, the same low noise front end Sound Devices puts in its bigger recorders, in a box the size of a sandwich. Run a boom and two radio mics, send a stereo mix to camera and run timecode into the aux input. Your lower back will thank you.

It's the recorder in our Indie Location Sound Recording Kit B. We also hire the original MixPre 6 if you need more inputs on a budget.

Is 32 bit float better than limiters?

They solve the same problem in different ways. 32 bit float records with so much headroom that clipped or quiet takes can be fixed in post. Limiters stop the level going too hot while you record at 24 bit. The MixPre 6 II has both, and the 633 relies on limiters alone.

Float is a brilliant safety net when nobody can ride the levels. But it doesn't replace good mic placement or a sensible gain setting, and noise recorded at the source stays there. On a scripted job with a recordist mixing as they go, a 633 with its limiters does the job without leaning on the edit.

Whichever recorder you hire, the mics matter as much. Our lists of the best shotgun microphones for film and the best lavalier microphones for film cover the boom and the radios.

Questions we get asked