Sound Devices 633 Portable Mixer and Recorder

$3,575.00 USD

The Sound Devices 633 is a compact, six-input mixer with integrated 10-track recorder featuring PowerSafe technology.



Special considerations may apply if this item is received outside of North America. Please read for details.

Sound Devices 633 Portable Mixer

The Sound Devices 633 is a compact, six-input mixer with integrated 10-track recorder featuring PowerSafe technology. It offers six analog inputs and records to SD and CompactFlash memory cards. The 633 is designed for audio professionals requiring go-anywhere portability, without compromising recording or mixing capability.

The 633 offers three high-bandwidth mic/line inputs on XLR connectors, complete with phantom power, highpass filter, input limiter and variable pan. Three additional line-level inputs on TA3 (mini-XLR) connectors offer flexibility for more complex productions. All inputs are assignable to its six output buses, Left/Right plus Aux 1/2/3/4.

All six inputs plus output buses Left/Right and Aux 1/2 can be recorded to individual tracks. The Sound Devices 633 offers 10-track 24-bit, 48 kHz uncompressed WAV recording (96 kHz and 192 kHz sampling up to six tracks) to SD and CompactFlash memory cards. The two cards can be set independently, recording either identical material for a real-time backup, or combinations of WAV and MP3 files.

Powered by a unique Quad Power supply with PowerSafe technology, the unit is operational from any of four power sources. Sources can include external DC (12-18 V), two removable 7.2 V L-type lithium ion cells, and six internal AA batteries. The 633 automatically switches from one power supply to the next when power is exhausted or removed. With its combination of power sources, the Sound Devices 633 can operate for a full production day on batteries alone.

When all power sources are removed or depleted, the unit’s PowerSafe circuitry is activated. PowerSafe keeps the 633 operating for up to 10 seconds and ensures that all file operations are fully closed and


  • Six analog inputs (3+3); three full-featured mic/line preamps plus three line-level inputs, each with dedicated front-panel faders and PFLs
  • 10-track recording, polyphonic or monophonic broadcast WAV files @ 24-bit 48 kHz (96 kHz and 192 kHz sampling for 6 tracks), time code stamped MP3. Simultaneous or independent recording to SD and CompactFlash card
  • 6 mix buses, left/right main plus Aux 1/2/3/4
  • PowerSafe Circuitry offers complete file protection from power loss. Ten second internal power reserve closes files and shuts down unit.
  • Quad Powering offers class-leading powering flexibility from four available power types, easily power the 633 for a full production day.
  • Two second power on-to-recording. Never wait on sound!
  • AES input, two-channel AES3 or AES42, four channels of AES output
  • Accurate Time Code Master Clock generator and reader, 0.5 frame per day accuracy
  • Clear, fast, easy to navigate controls and interface; visible in all light conditions, configurable metering and display
  • USB Keyboard connection for quick and easy metadata entry.
  • Input delay selectable on all six inputs plus output bus delay on all six buses.
  • User-configurable headphone presets plus a headphone favorite mode for quick source selection
  • Small, lightweight, compact chassis made from molded, metalized carbon fiber


Analog Inputs

Frequency Response10 Hz to 40 kHz ± 0.5 dB, -3 dB @ 65 kHz (192 kHz sampling rate reference 1 kHz)
THD + Noise0 .09% max (1 kHz, 22 Hz–22 kHz BW, fader at 0, 0 dBu output)
Equivalent Input Noise-126 dBu (-128 dBV) maximum. (22 Hz – 22 kHz bandwidth, flat filter, trim control fully up)
Input Types
  • XLR Mic: active-balanced for use with ≤600 ohm mics, 4k ohm actual; 12V or 48V phantom power, 10 mA max
  • XLR AES: AES3 or AES42 (10 V power), SRC
  • XLR Line: active-balanced for use with ≤2k ohm outputs, 10k ohm actual
  • TA3 Line: active-balanced for use with ≤2k ohm outputs, 10k ohm actual
  • RTN (3.5 mm): unbalanced stereo for use with ≤2k ohm outputs, 30k ohm actua
Maximum Input Level
  • XLR Mic: 0 dBu (0 .78 Vrms)
  • XLR Line: +40 dBu (80 Vrms)
  • RTN (3 .5 mm): +24 dBu (12 .4 Vrms)
Maximum Gain
  • Mic-In-to-Line-Out: 91 dB
  • Mic-In-to-Aux-Out, -10 Out: 77 dB
  • Line-In-to-Line-Out: 39 dB
High-Pass FiltersSweepable 80 Hz to 240 Hz, 12 dB/oct at 80 Hz, 6 dB/octave at 240 Hz
Microphone Powering (each analog Input selectable)
  • 12 V Phantom: through 680 ohm resistors, 10 mA per mic available
  • 48 V Phantom: through 6 .8k resistors, 10 mA per mic available
Analog Input Limiters (Inputs 1-3)
  • Affects the output of the mic preamps only (‘Trim’ stage) · +16 dBu threshold (fixed)
  • 20:1 limiting ratio
  • 1 mS attack time
  • 500 mS release time
Digital Input Limiters (Inputs 1-6)
  • Post-fader
  • +6 dBu to +18 dBu threshold (adjustable) · 20:1 limiting ratio
  • 1 mS attack time
  • 500 mS release time

Digital Inputs

  • AES42 Mode 1, provides +10 V Digital Phantom Power

Analog Outputs

Output Type
  • XLR Line: Active Balanced for use with ≥600 ohm inputs
  • XLR -10: Active Balanced for use with ≥10k ohm inputs
  • XLR Mic: Active Balanced for use with ≥600 ohm inputs
  • TA3 Active Balanced Mic/Line: pin-2 and 3 driven, for use with ≥3k ohm inputs · X3,X4 (3 .5 mm): Unbalanced, stereo, for use with ≥6k ohm inputs
  • Headphones (1/4”): Unbalanced, stereo, for use with 8-2k ohm headphones
Output Impedance (ohms actual)
  • XLR and TA3 balanced outputs: 100 ohms at Line setting, 3 .2k ohms at -10 setting, 150 ohms at Mic setting
  • TA3 Balanced Outs: 1k ohms at Mic and Line settings · X3,X4 (3 .5 mm): 100 ohms
  • Headphones (1/4”): 100 ohms
Line Output Clipping Level (1% THD)20 dBu minimum with 10k load
Maximum Output Level
  • Line: +20 dBu (7.8 Vrms)
  • -10: +6 dBu (1.5 Vrms)
  • Mic: -20 dBu (0.078 Vrms)
  • Aux 3/4: +6 dBu (1.5 Vrms)
Output Limiters
  • Affects the outputs of the mixer
  • Threshold selectable from +4 dBu to +18 dBu, 1 dB steps · 20:1 limiting ratio
  • 1 mS attack time
  • 500 mS release tim

Digital Outputs/Recorder

AES3 Output
  • Transformer-balanced AES Out A,B on XLR
  • 110 ohm, 2 V p-p, AES and S/PDIF compatible with RCA adaptor
Sampling Frequency
  • 44.1 kHz
  • 47.952 kHz
  • 48 kHz
  • 48.048 kHz
  • 88.2 kHz
  • 96 kHz
  • 192 kHz
A/D24 bit
A/D Dynamic Range114 dB, A-weighted, typical
Recording Storage Type
  • SD, SDXC, SDHC Card
  • FAT32 or exFAT formatted, will format media on-board
  • CompactFlash (CF)
  • FAT32 formatted for CF and SD <32 GB, exFAT for SD cards >32 GB, will format memory cards in-unit
File Type
  • Record: WAV (Broadcast Wave File format), polyphonic or MP3
  • Playback: WAV (Broadcast Wave File format), polyphonic or MP3
Timecode and Sync
  • Modes Supported: off, Rec Run, Free Run, 24h Run, External
  • Frame Rates: 23.976, 24, 25, 29.97DF, 29.97ND, 30DF, 30ND
  • Accuracy: Ambient generator, 0.2 ppm (0.5 frame in 24 hr)
  • Time Code Input: 20k ohm impedance, 0.3 V – 3.0 V p-p (-17 dBu – +3 dBu)
  • Time Code Output: 1k ohm impedance, 3.0V p-p (+12 dBu)
Sample/Timecode Accuracy± 0.2 ppm (0.5 frames per 24 hours)
  • External: 10-18 V on locking 4-pin Hirose connector, pin-4 = (+), pin-1 = (-).
  • Removable x 2: 7.2 V (nominal) Sony L-type Li-ion, operational from 6.5–8.5 V,
  • Internal: accepts 6 AA-sized (LR6) batteries, 1.2-1.6 V nominal (NiMH rechargeable compatible)
  • Operating: -20°C to 60°C, 0 to 90% relative humidity; (non-condensing)
  • Storage: -40°C to 85°C
Dimensions and Weight
  • Dimensions: 6 cm x 24 cm x 14 cm (H x W x D); 2.2” x 9.4” x 5.6”
  • Weight: 1.1 kg; 2 lbs. 9 oz. (unpackaged, without batteries)


1) Where in the signal path are the A/D and D/A converters placed?

A/D conversion occurs immediately after the hardware limiters on channels 1-3 and right after the input on 4-6. The signal remains in the digital realm until it hits the D/A converter directly before the outputs.

2) What are the details of the unit’s high-pass filters and limiters?

The 633’s unique high-pass filter circuit occurs before any amplification of the signal, resulting in higher headroom for the remaining audio. Each channel’s HPF can be adjusted in 10 Hz increments from 80 to 240 Hz. The roll-off has a compound slope that varies depending on where it’s set.

The 633 has two types of onboard limiters, analog and digital. The analog input limiters affect only signal passing through the mic preamps on channels 1-3. These limiters are pre-fader with a fixed threshold of +16dBu, 20:1 ratio, 1 mS attack and 500 mS release. The analog input limiters are always on, protecting the A/D converter from overages.

There are post-fader digital limiters on each input, the L/R mix bus, and the Aux 1/2 output bus. These limiters can be globally switched on/off via the software menu. They have a 20:1 ratio with 1 mS attack and 500 mS release. You can select either a hard knee or soft knee reduction curve. The default threshold is +16dBu, but they can be adjusted from +4dBu to +18dBu.

3) Can inputs 4, 5, and 6 be panned within software menu?

Yes, but inputs 4, 5, and 6 can only be centered or hard panned. However, if you have the recorder set to capture ISO tracks, they can always be panned freely in post.

4) Does the 633 support Channel Linking? And which channels can be linked?

Channels 1-2 and 5-6 can be linked as stereo pairs or M/S pairs. This also links their respective limiters together to preserve imaging during gain reduction. The channels will retain separate trim and HPF controls, while their fader level and stereo balance will be linked to the dials of either channel 1 or 5.

5) Does the 633 have a 32-bit floating point DSP?


6) Can the 633 simultaneously record WAV and MP3 files?


The 633’s default setting is to record all 10 tracks (6 ISOs, L/R, Aux 1/2) to a polyphonic wav file that is mirrored on both media cards. You can easily set one of the cards to record either a stereo MP3 of the L/R bus or the Aux 1/2 bus.

Other options include recording polyphonic WAVs of just the 6 ISO tracks, just the L/R bus, or just the Aux 1/2 bus. You can also set it to record mono WAV files of all 10 tracks or just the 6 ISOs.

Simultaneous MP3 recording cannot be done when the 633 is recording at sample rates above 48 kHz.

7) Additional concessions at 88.2, 96, or 192 kHz sampling rates:

At these higher sample rates, the recorder only captures the 6 ISO tracks. The maximum pre-roll time reduces from 6 seconds to 3 seconds in 88.2 or 96 kHz, and further to 1 second in 192 kHz.

In 88.2 and 96 kHz, the limiters and high-pass filters function as normal. However, in 192 kHz, all digital limiters are disabled, leaving only the 3 analog input limiters in effect. The high-pass filters can either be set at 50 Hz or disengaged.

8) How does the timecode circuitry compare to that of the 664?

It is identical.

9) Does the 633 have Word Clock I/O?


10) Does the 633 support Multi-Unit Linking?


11) What is its total battery life?

With AA batteries and two Sony L-type cells installed, the 633 can be in use for 30+ hours.

12) When the 633 is plugged into an external DC power supply, will it charge the Sony L-type cells?


13) Does the 633 have Mix Assist?


14) Does the 633 offer T power?


15) Will Sound Devices be releasing a CL3 Attachment for the 633?

As of now, no.

16) How do you connect an external keyboard?

The 633 comes with a USB B-to-A adapter, allowing you to plug any standard USB keyboard into the USB connector on the unit’s right panel.

17) Do you need to unplug the external keyboard to change media cards?

Yes. The media door cannot be opened with a USB cable plugged in.

18) Will the 633’s LCD be visible in bright conditions?

The 633 has a daylight mode that changes the LCD’s color scheme to be more visible in direct sunlight.

19) Is the 633 moisture resistant?

Yes, the 633 has a splash-proof front panel and sealed connections allowing you to safely record in a drizzle.

20) What is the size and weight difference between the 633 and similar units?

The 633 measures 9.4″ wide, 5.6″ deep, 2.2″ tall, and weighs 2.56 pounds without batteries installed. Or in metric, that’s 24 cm wide, 14 cm deep, 6 cm tall, and 1.1 kg.

The 664 is 12.6″ wide, 7.8″ deep, and 2.1″ tall, weighing in at 4.75 pounds. Or 32 cm wide, 19.8 cm deep and 5.3 cm tall, with a weight of 2.15 kg. This weight measurement is also taken without batteries installed.

The Zaxcom Maxx is 7.5″ wide, 5.25″ deep, 2″ tall, and weighs 2.5 pounds. Or 19 cm wide, 13.3 cm deep, 5 cm tall, and 1.13 kg.

Manuals & Docs