The Sound Devices 633 6-Input Field Production Mixer and Digital Recorder is designed for production audio mixing and recording on set and in the field. The unit is housed in a compact lightweight molded metalized carbon-fiber chassis and features six analog inputs: three XLR microphone preamplifier inputs with selectable phantom power, high-pass filters, input limiters, faders and variable pans, as well as three line-level TA3 (mini-XLR) inputs. The first XLR input can also function as an AES digital input and accept AES3 or AES42 inputs with +10 V phantom power for digital microphones. The two XLR outputs can also be used as four channels of AES output.

All of the unit’s inputs can be assigned to the mixer’s six output buses: left, right, Aux 1, Aux 2, Aux 3, and Aux 4. Selectable input delay on all six inputs and output bus delay on all six buses makes it easy to correct lip-syncing issues between audio and video. The unit’s 1/4″ headphone output can be configured with different user-presets and a favorite mode allows for quick source selection when monitoring.

The device can record to an SD card, CompactFlash card, or both memory card formats simultaneously in mono or poly WAV or MP3 file formats. The cards can be set to record redundant backups or combinations of WAV and time-coded MP3s for dailies and transcription purposes. The six inputs, output bus left, output bus right, aux 1, and aux 2 can all be recorded to individual tracks at 24-bit 48 kHz resolution for a total of ten tracks. This is useful for having both individual tracks from the six inputs, as well as the recordist’s field mix. Up to six tracks can be recorded at 24-bit 96 kHz and 192 kHz sample rates.

The device can be powered by any of four different simultaneously coexistent power sources, including 12 to 18 VDC from an external power supply (sold separately), two removable 7.2 V L-type lithium-ion batteries (sold separately), and six internal AA batteries (NiMH recommended, sold separately). The unit’s LCD display indicates battery levels for the various sources. When one power supply is depleted, the mixer will automatically switch to the next power supply without interruption. When all power supplies are depleted, the device’s built-in PowerSafe trickle-charge battery will keep the device running for an additional 10 seconds so that all files can be saved and closed properly and ensure that no data is lost. The built-in battery also allows the device to power up and start recording in two seconds for near immediate operation.

The unit is built with dedicated ergonomic controls for all major mixing and recording functions and features an LCD display that can be viewed in all types of lighting. The background of the display can be changed in the menu settings between day and night modes to make the meters easier to read. An integrated high-accuracy Timecode generator supports all common rates and modes. A USB port allows for the connection of a computer keyboard for easy entering of metadata to better organize files. The unit is built to be durable in the field, and includes gasket seals to protect the internal circuitry from the elements.

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Additional information

3 x XLR 3-pin Female Inputs
3 x TA3 (mini-XLR) inputs
2 x XLR 3-pin male outputs (left and right)
1 x 1/4" headphone jack
2 x TA3 outputs (Aux 1 and Aux 2)
1 x 1/8" stereo output (Aux 3 and Aux 4)
1 x RTN output
1 x Timecode output
1 x 4-pin Hirose power connector

Frequency Response

10 to 40,000 Hz ±0.5 dB
-3 dB at 65,000 Hz (192,000 Hz sampling rate reference at 1,000 Hz)

THD + Noise

0.09% max (1,000 Hz, 22 to 22,000 Hz BW, fader at 0, 0 dBu output)

Equivalent Input Noise

-126 dBu (-128 dBV) maximum (22 to 22,000 Hz bandwidth, flat filter, trim control fully up)

Input Type

XLR Mic: active balanced for use with ≤600 Ω microphones, 4,000 Ω actual, 12 V or 48 V phantom power, 10 mA max

XLR AES: AES3 or AES42 (10 V power), SRC

XLR Line: active-balanced for use with ≤2,000 Ω outputs, 10,000 Ω

TA3 Line: active-balanced for use with ≤ 2,000 Ω outputs, 10,000 Ω actual

RTN (3.5 mm): unbalanced stereo for use with ≤ 2,000 Ω outputs, 30,000 Ω actual

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)

High-Pass Filter

Sweepable 80 to 240 Hz
12 dB/octave at 80 Hz
6 dB/octave at 240 Hz

Microphone Power

Each analog input is selectable
12 V phantom through 680 Ω resistors, 10 mA per mic available
48 V phantom through 6,800 Ω, 10 mA per mic available


AES42 Mode 1: provides +10 V digital phantom power

Output Type

XLR Line: active balanced for use with ≥ 600 Ω inputs

XLR -10: active balanced for use with ≥ 10,000 Ω inputs

XLR Mic: active balanced for use with ≥ 600 Ω inputs

TA3 Active balanced Mic/Line: pin-2 and 3 driven, for use with ≥ 3,000 Ω inputs

Aux X3 and X4 (3.5 mm): unbalanced, stereo, for use with ≥ 6,000 Ω inputs

Headphones (1/4"): unbalanced, stereo, for use with 8 to 2,000 Ω headphones

Output Impedance

XLR and TA3 balanced outputs: 100 Ω at line setting
3,200 Ω at -10 setting
150 Ω at mic setting

TA3 balanced outs: 1,000 Ω at Mic and line settings
Aux X3, X4 (3.5 mm): 100 Ω
Headphones (1/4"): 100 Ω

Line Output Level

Clipping: 20 dBu minimum with 10,000 Ω 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)


Affects the outputs of the mixer
Threshold selectable from +4 dBu to +18 dBu, 1 dB steps
Ratio: 20:1
Attack time: 1 ms
Release time: 500 ms

Maximum Gain

Typical: Trim, Fader, Master, Phones, RTN fully up
Mic-level input
Master outs (XLR) at line: 91 dB
Master outs (XLR) at -10: 77 dB
Master outs (XLR) at mic: 51 dB
X3, X4 Outs (3.5 mm): 77 dB
Headphones (1/4"): 107 dB

Line-level input
Master outs (XLR) at line: 51 dB
Master outs (XLR) at -10: 37 dB
Master outs (XLR) at mic: 11 dB
X3, X4 Outs (3.5 mm): 37 dB
Headphones (1/4"): 67 dB

Headphones (1/4"): 5 dB

AES3 Output

Transformer-balanced AES Out A, B, on XLR
110 Ω, 2 V p-p
AES and S/PDIF compatible with RCA adaptor

Sampling Frequency

44,100 Hz
47,952 Hz
48,000 Hz
48,048 Hz
88,200 Hz
96,000 Hz
192,000 Hz

Bit Depth


Dynamic Range

114 dB, A-weighted, typical

Recording Storage

Please see manufacturer's site for a list of approved cards

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

Formats cards in-unit

File Type

Record: WAV (Broadcast Wave File format), polyphonic or MP3
Playback: WAV (Broadcast Wave File format), polyphonic or MP3


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)

Timecode input: 20,000 Ω impedance, 0.3 V to 3.0 V p-p (-17 dBu to +3 dBu)

Timecode output: 1,000 Ω impedance, 3.0 V p-p (+12 dBu)


Sample/Timecode: ± 0.2 ppm (0.5 frames per 24 hours)


External: 10 to 18 V on locking 4-pin Hirose connector, pin 4 = +, pin 1 = –
2 x Removable 7.2 V (nominal) Sony L-type Li-ion, operational from 6.5 to 8.5 V

Internal 6 x AA (LR6) batteries, 1.2 to 1.6 V nominal (NiMH rechargeable compatible)


Operating: -4 to 140° F (-20 to 60° C)
Storage: -40 to 185° F (-40 to 85°C)

Humidity (Non-condensing)

0 to 90% relative humidity

Dimensions (H x W x D)

2.2 x 9.4 x 5.6" (6.0 x 24 x 14 cm)


2.56 lb (1.10 kg)


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