688 Firmware v4.50

688 with Wingman app on iPhone

Sennheiser EK-6042n

The 688/SL-6 now has SuperSlot support for the Sennheiser EK-6042.

Sound Devices 688 firmware - (v4.50) provides a firmware update for the 688 field production mixer, which includes support for Sennheiser EK-6042 wireless receiver in the SL-6 accessory, a shortcut for toggling On/Off tone, and other performance enhancements.

It is highly recommended that users update to the latest version of firmware available as soon as possible.

Download the available 688 User Guide. It is up-to-date with all relevant features and functionality changes provided in the latest released versions of firmware.

NOTE: Updating the 688 to v4.50 requires the Wingman app to be v1.01. It is important that, before launching Wingman, the 6-Series mixer is running v4.50 and the Wingman app on the iOS device is updated to v1.01. Click HERE to get v1.01 from the Apple App Store.

Last update February 2, 2017

Changes introduced in 4.50 include:

New in 688 v4.50

  • SL-6 SuperSlot Support of Sennheiser EK-6042
  • Ctrl+T keyboard shortcut to toggle Tone On/Off

Changed in 688 v4.01

  • High-Pass Filter now returns to last used value when toggled on and off rather than always reset to 150Hz.
  • Recording of 192 kHz monophonic wav files is no longer allowed. In previous firmware, recording was not prevented even though it was classed as an unsupported mode. Set to polyphonic when recording 192 kHz.

Fixed in 688 v4.50

  • Long file names on exFAT formatted media are truncated.
  • Improved how MixAssist and Dugan AutoMix respond to LR Attenuation and Pan values.
  • Factory Option for Scene Name can be overwritten by user if Scene Name is edited during record. This can cause Scene Increment Mode to stop working.

Known Issues

The list below are the published known issues for the latest 688 Firmware.

  • The CL-12 does not always initialize when connecting to the 688 if the CL-12's DC Boost Input is connected.
    When disconnecting the CL-12 from the 688: Remove the DC Boost Input micro USB cable before disconnecting the CL-12/688 USB A to USB B cable. When connecting the CL-12 to the 688: Connect the CL-12/688 USB A to USB B cable before connecting the DC Boost Input micro USB cable.
  • Rare issue where the system clock gets set to an invalid date. This can cause the daily folder to be incorrectly named and therefore the files get stored in the wrong folder. As of V2.00+, if the 688 detects an invalid date, it will display the following message: “System date error detected. Please reset time and date.”

4.01 - Oct 18, 2016




  • Wingman meter response is sluggish when WM-Connect is connected to the CL-12 Keyboard port.

NOTE: Requires updating the Wingman app to v1.01. It is important that, before launching Wingman, the 6-Series mixer is running v4.01 and the Wingman app on the iOS device is updated to v1.01.

Fixed in Wingman v1.01

  • Wingman meter response is sluggish when WM-Connect is connected to the CL-12 Keyboard port.
  • Wingman display and metadata errors with 6-Series after the app has been brought in and out of Standby Mode.
  • iPad Pro 12.9” minor display issue in the Devices Found page.
  • Intermittent issue where Track Arm status shows incorrect state at sample rates 88.2kHz and above.
  • Track arming display inconsistencies.

4.00 - Sept 9, 2016


  • Support for Wingman, an iOS application by Sound Devices, LLC and the hardware accessory, WM-Connect, a Bluetooth® Smart USB dongle.
    • Wingman is a free iOS application available as a free download from the Apple® App Store.
    • WM-Connect is an optional hardware accessory that connects to the 688 USB Port via USB B to USB A adapter or directly to CL-12 Keyboard port. The Bluetooth Smart device automatically pairs with mobile devices running iOS v8.0 or later.
  • From the Wingman app, you can:
    • Remotely control Record, Stop, False Take, and Circle commands
    • View Audio Metering, Timecode, Absolute time, Record Status, and more
    • Arm/Disarm Tracks for recording and manage track naming
    • Edit metadata of upcoming, current, and up to 50 previous recorded takes, including: scene, take, notes, track names, etc.
    • Manage, Create, and Email Sound Reports


  • Channel 7-12 Trim Gain factory default is now 0 dB; it was 6 dB.


  • Intermittent Lock Up when restoring a saved Setup file.
  • Unable to select lowest available frequency of the Lectrosonics SRc.
  • Pressing Meters button from Take List>Take Edit screen returns UI to the wrong Meter View.
  • Reduced the likelihood of unit locking up when powering down.
  • Reduced the likelihood of date/time corruption.

3.11 - July 25, 2016


  • Rare issue where Channels 7-12 and RTNs did not properly initialize at boot up.
  • Issue where SuperSlot-compatible Lectrosonics SRb and SRc Tuning Groups U and V scrolling did not work properly.

3.10 - July 5, 2016


  • Support for 3rd party wireless control, timecode and metadata management including:
    • Timecode Systems :WAVE and PureBlend's MovieSlate® iOS app
    • Ambient® Master Lockit.

Note:Additional 3rd-party hardware and software is required for this integration. Click here for more information.

  • New menu option to disable the CL-12 Output level controls (L, R, X1 and X2). Options for MENU > CL-12 > L-X2 Gain Pots include: Enable or Disable.
  • 20 dB of gain added to the Slate Mic — now adjustable from 0 to 56dB in 1dB increments.
  • New SL-6 Receiver Slot Power menu options for Slots 1-3 provides ability to power off unused receiver slots via the 688 interface to save power. This is the best method for powering receivers on or off when used in the SL-6.
  • Take Designator can now be set to any alpha character or '-' (T is default) in MENU > FILE STORAGE > Take Designator.
  • New SL-6 Lectrosonics SRc screen provides the ability to put the SRc into IR Sync mode directly from the 688 UI.


  • Behavior to PFL action when in Input Settings > Edit Channel # Name screen. Now when selecting the same PFL, the track name reverts to the previous entry and returns to the Input Settings screen. Selecting another PFL cancels name changes and provides immediate entry to the new channel's Input Settings screen.
  • CL-12 User Button option "MixAssist" has been renamed to "Auto Mixer".
  • While recording, the Take List's Circle option for the Current Take is no longer available.


  • Arming paired LR or X1/X2 tracks using the CL-12 LR, X1/X2 pots did not correctly operate on the pairs.
  • Track Name entries from Input Settings Window would not hold if that track name already existed.
  • Channels turned off from the CL-12 were reverting back to On after a power cycle.
  • Some channel fader values, if attenuated to -infinity after power down, are not correctly applied after powering unit on.
  • CL-12 Mix Bus Track LEDs could get out of sync when linked.
  • When scrolling frequency upwards in the Rx Screen with the Lectrosonics SRc in Normal Tuning mode the frequency jumps incorrectly to the last frequency in the band.

3.01 - April 27, 2016


  • Scrolling the SL-6 RF Scan plot using the HP encoder now skips over gaps of unused RF frequencies allowing for quicker scrolling through the RF plot.


  • Lectrosonics SRb and SRc are temporarily set to an output level of -50 dB during the SL-6 RF Scan process. This is to avoid unwanted loud signals sent to the 688 during the scan.


  • SL-6 RF Scan does not complete correctly when three Wisycom MCR-42s are in use.
  • General clean up of SL-6 RF Scan with Wisycom MCR42, including faster scan time.
  • Lectrosonics SRb and SRc do not revert to previously selected frequencies after the SL-6 RF Scan when a frequency wasn’t assigned to the Receiver.
  • SRc Block 606 Tx Switches are not displayed correctly in the 688 Rx Screen.

3.00 - April 18,2016


  • 12-channel automatic mixing with Dan Dugan automixing.
  • MixAssist now allows control of the Off-Attenuation setting. Range is 6 dB to 40 dB in 1 dB increments.
  • SL-6 supports Lectrosonics SRc.
  • The SL-6 supports RF Scan with Wisycom and Lectrosonics SRb & SRc SuperSlot-compatible receivers, which includes:
    • Ability to scan the entire receiver frequency spectrum and display detailed results on the 688's larger, colorful LCD.
    • Use the Select encoder to zoom in and out; Use the Headphone encoder to horizontally scroll through the scan and assign a selected frequency to available receiver channels.
    • Wisycom RF Group Scan from the Wisycom Rx screen: Initiates scan and lists channels for the selected group by returned dBuV values.
    • Lectrosonics RF Scan from the Lectosonics Rx screen: Scans the frequency range of the receiver, displays results, and enables frequency assignment to the receiver's available channels.


  • CL-12 Fader Calibration now also includes a fader down calibration.
  • Relocated Compatibility on (SL-6) Lectrosonics SRb Rx screen to the SRb menu.


  • CL-12 MixAssist LEDs on channels 10-12 do not show correct MixAssist activity.
  • Unable to use SL-6 Rx Screens to scroll through Lectrosonics SRb user-defined tuning groups U and V.
  • Missing support of Lectrosonics Block 606.
  • Sluggish navigation in the SRb Rx Screen Menus.

2.11 - November 17,2015


  • The Circle Take (@) button on the CL-12 is locked out while in record and now always applies to Current Take.
  • Entering track names with no characters are not allowed. This is to prevent track name shifting issues.


  • The REC button on the CL-12 now flashes during the record pending state.
  • The 688 Power LED no longer disappears whenever CL-12 & CL-6 are both connected to mixer.
  • Previously, when the SEL follows PFL feature was disabled, selecting an input channel's PFL and SEL together, then pressing another SEL button would result in illumination of two SEL buttons on the CL-12. This has been fixed, so that when SEL follows PFL is disabled, the press of a single SEL button will replace selection of an earlier one.
  • Eliminated zipper noise when attenuating X1 and X2 track levels.
  • Eliminated stepping noise when attenuating L, R, X1, X2 output levels.
  • Reduced headphone monitor noise when adjusting headphone gain.
  • Fixed a rare issue where user settings could be lost over power cycles.
  • Fixed a rare issue where CL-12 power warning messages could appear at boot up.
  • Fixed an issue where changes to the CL-12's L, R, X1, and X2 pot positions were not being read after a cold boot.
  • Fixed an issue where the CL-12 was showing internal tone 2 dB higher on its meters.
  • NP1 to DC switchover with an SL-6 connected is now fixed.

2.10 - November 2, 2015


  • Support for the new CL-12 Linear Fader Controller, including:
    • 12 100 mm linear input faders (Penny & Giles option with CL-12 Alaia)
    • 3-band EQ individually set for each input
    • L, R, X1, X2 level control, routing, arming, and 22-segment metering inc. limiter activity
    • 2 Com private line circuits
    • Numerous quick-access buttons to key functions inc. metadata, transport, SuperSlot, TC, coms/returns, arming, routing, etc.
    • USB ports for keyboard and lamp
    • Three user-programmable buttons
    • Plus more...


  • Previously, tone did not get sent to headphone monitor after monitoring a RTN, requiring a temporary workaround. This issue has been fixed.
  • Previously, there was a date corruption issue with ExFAT formatted media containing more than 200 files. This issue has been fixed.

2.01 - August 21, 2015


  • Analog Output levels of SuperSlot compatible receivers have been reduced to eliminate the possibility of SL-6 input overload. Lectrosonics SRb receivers are now set to -6. Wisycom MCR42 receivers, when in analog output mode, are set to 0 dBu.

2.00 - June 26, 2015


  • Support for the SL-6 Powering and Wireless System.
  • Headphone level range extended from -30dB to -42dB.
  • Extra 6dB of trim gain available to line inputs 7-12.
  • Phase inversion now available for all 12 inputs (1-6 in Input Settings Window and 7-12 via Main Menu>Inputs>Input 7-12 Phase).
  • Added QR Codes for smart phone access to online documentation including Approved Media List and User Guide. A QR code reader app is required.
  • New User Bit mode allows jamming of External Timecode User Bits.


  • Word Clock In Termination menu name changed to Word Clock Sensitivity. Menu options are High (no termination) and Low (75 ohm termination).
  • Added notification to change the internal real time clock battery when it is low.


  • User assigned headphone presets using prefade Iso signals would switch to post-fade when Mono was selected.
  • Tape Out wouldn't return to the correct Tape Out Source menu setting after RTN Loopback Mode was activated.
  • Limiter activity for inputs 1-4 incorrectly showing on X3-X6 output meter page.
  • Reduced pop in headphones going from headphone source to return for the first time.
  • Intermittent problem where LCD could boot up solid black or with missing colors.
  • Sound report track names for X1 and X2 being written on track 9 and 10 respectively.
  • Intermittent issue where digital readout of trim values at power up would be incorrect.
  • Scene name shortcut (HP + RTN) editing factory the "None" option option causing "None" to disappear and breaking Scene Increment Mode.
  • When UBits are set to one of the date modes the UU field metadata stamps were following the take number.
  • UBits UU fields are now restored after loading user setup files.
  • Headphone monitor levels were too low when the tone generator was active.
  • Internal tone generator was overriding RTN signal in headphone monitor.
  • Lock up when adding notes exceeding the 200 character limit.
  • Keyboard sequence involving Shift key would sometimes repeat the same character as if the key was being held down.
  • In the file list, FAT32 media files would incorrectly display modified time instead of creation time.
  • Output delay frame calculation error.
  • Intermittent issue where AES trim gain range was not the same across all channels.

1.00 - initial release

Please read and follow the steps below carefully. You may want to print them before upgrading firmware.

Sound Devices recommends backing up any existing audio data that may reside on the recorder. While no data on the storage is changed during the update process, it is best practice to backup the unit. In addition, it is highly recommended to save the current device settings since a firmware update can result in settings changing to factory default.

Prepare to Update

  1. Download the 688 firmware file 688_4.50.zip using the link below.
    From the zip archive, extract the file within named 688_4.50.prg file. Copy this .prg file to the root level of an approved SD or CF memory card. Do not place the file in any folder. Do not place the 688_4.50.zip file on the SD or CF card. The card must be formatted in the 688.
  2. Apply Update to 688.
  3. Power the 688 from external DC. Do not perform the update with low batteries or unstable power sources.
  4. Power down the 688 if it is already powered up.
  5. Insert the SD or CF card with the .prg file.
  6. Power on the 688.
  7. Navigate to Setup Menu option SYSTEM > Update Firmware and follow the on-screen instructions.
  8. When the update is complete the 688 will power cycle itself. The version number 688_4.50 will be displayed briefly on the splash screen while booting up. A message box appears "Firmware updated successfully Version:688_4.50". Press "OK". Please note any changes or additions to the Setup Menu (if applicable). Consult the 688 User Guide and Technical Information for details.