DSPconfig

v26.9.1 - 30/09/2026

New features:

• Refuse to upgrade firmware, or to read or write profiles, over a USB connection slower than high speed. Suggest using a different cable or port and not going through a hub.
• On firmware 1.9, follow each stage of a firmware upgrade as the DSP reports it, rather than estimating from a timer, and show which stage has been reached.
• Pick up an interrupted upgrade when the DSP next connects, wait for anything still in progress to finish, and offer to retry. The DSP keeps running its previous firmware in the meantime. A failed upgrade now has a Retry button, and no message asks you to power cycle the DSP: keep it powered and retry from DSPconfig.
• Update the built-in recovery image of DSP-8C units that left the factory with firmware 1.5 during an upgrade.
• Improved logging.

Fixes:

• Offer Retry when an upgrade left unfinished on firmware 1.6 to 1.8 is picked up, instead of asking you to turn the DSP off and on again.
• Keep asking you to keep the DSP powered while it restarts at the end of a firmware update, instead of briefly showing the "plug in your DSP" screen.
• Show the DSP even when its profiles cannot be read, instead of staying on the "plug in your DSP" screen, and recover by itself when an earlier copy of DSPconfig was closed part way through reading profiles.

Firmware updates - version 1.9, for the DSP-8C:

• Fix a DSP that the computer recognised but DSPconfig could not connect to until it was power cycled. This happened when a USB request was abandoned part way, for example by closing DSPconfig or unplugging the cable at the wrong moment.
• No longer hold up the USB connection whilst the DSP writes firmware to its memory, so DSPconfig can follow every stage of an upgrade.
• Report the progress of an upgrade to DSPconfig, and refuse an upgrade over a full-speed USB connection before anything is erased.
• Show "Upgrade interrupted" on the display after an interrupted upgrade, and an "Upgrade needed" marker on the overview screen until an upgrade completes.
• Support the one-off recovery image update for DSP-8C units that left the factory with firmware 1.5.
• Fix a profile being read back damaged after DSPconfig was closed part way through reading profiles.

v26.9.0 - 23/09/2026

New features:

• Add a 'Signal chain' option to the filter editor chart, showing the channel's full response from input to output, including the input channel(s) feeding it. The trace is labelled in the chart's corner with its source (Left input, Right input or Left + Right) and whether the channel is muted, and its phase has the output delay and any FIR filter's latency removed so that the shape of the response is readable.
• Zoom the filter editor chart with the mouse wheel and pan it by dragging, from 10Hz up to Nyquist and down to a 24th of an octave. The home button that appears on the chart's toolbar, or a double-click on the chart, resets the view.
• Extend the chart's full frequency range to Nyquist (48kHz or 96kHz, depending on the profile's sampling rate), rather than stopping at 20kHz.
• Add three magnitude ranges to the chart, -12 to +6dB, -24 to +12dB and -50 to +20dB, so that small EQ adjustments are no longer vertically compressed. A trace running off the top of the chart is marked with an arrow.
• Move the chart's settings (Show phase, Show all filter traces, Signal chain, frequency range and magnitude range) onto the chart's toolbar and a new Options menu. Each chart type remembers its own settings between sessions; Signal chain is one setting shared by every chart.
• Allow EQ filters to be placed up to 40kHz, up from 22kHz. The old limit was inherited from REW, and left no way to correct the breakup resonance of a hard dome tweeter, which sits around 25 to 30kHz for aluminium or titanium and nearer 40kHz for beryllium.
• Windows: DSPconfig now comes as an installer rather than a standalone executable. It adds a Start Menu entry and an uninstaller, installs for the current user without asking for administrator rights, and installs over a previous version in place. An old DSPconfig.exe in your Downloads folder can be deleted; your settings are kept.
• macOS and Windows: 'Help > Check for Updates' can now download and install an update itself and restart DSPconfig, rather than only linking to the website.
• Linux: the .deb now adds CoLinear Acoustics' APT repository, so later versions arrive through apt upgrade or your desktop's update notifier. A new .rpm for Fedora and the Red Hat family does the same through dnf upgrade.

Fixes:

• Fix the phase of a minimum phase FIR filter being drawn incorrectly. The chart assumed the filter's delay sat in the middle of its taps, which is only true of a linear phase filter, so a minimum phase correction (from rePhase, for example) was drawn with its phase wrapping hundreds of times across the audio band. The delay is now measured from the filter's response. Only the chart was affected; the filter itself was always applied correctly.
• Fix a Custom biquad with a pole exactly on the unit circle drawing as a deep null instead of a peak.
• General performance optimisations.

Firmware updates - version 1.8, for the DSP-8C:

• Improve robustness of S/PDIF channel status handling, muting the output when non-audio data is being transmitted. Additionally, fix a sequencing bug which could mute all audio output when only the S/PDIF receiver should have been muted.
• Send correct channel status information on the S/PDIF output. It previously sent all zeros, which amongst other things told the receiving device the audio was at 44.1kHz whatever the actual sample rate.
• Windows: fix a DSP that Windows recognised but DSPconfig could not open, where the USB driver install had only half completed. The DSP now identifies itself to Windows using MS OS 2.0 descriptors, with which the driver installs completely.
• Fix the DSP repeatedly disconnecting and reconnecting on some computers whilst a profile was loading.
• Improve reliability and robustness of handling USB driver errors.
• Minor USB audio descriptor fixes.

v1.6.0 - 04/09/2026

New features:

• Add a setting under 'Device > Settings...' to configure what the overview screen shows: 'Combined', which is the master volume, audio source and selected profile as before, or 'Volume Only', which shows the volume alone in a larger font. Requires firmware 1.7.

Fixes:

• Align the output channel tap limits shown in the GUI with those the new firmware provides.
• Fix the peak meters freezing at whatever they last showed when the signal stopped changing, rather than falling away and settling.
• Fix the notification that a newer firmware version is available not appearing while a DSP is connected.
• Report a failed connection to a DSP once rather than repeatedly, and no longer retry it. A connection that fails is almost always something needing manual intervention, such as a second instance of DSPconfig already holding the device.
• Windows: fix DSP hotplug detection requiring the unit to be unplugged and reconnected by hand.

Firmware updates - version 1.7, for the DSP-8C:

• Restore the maximum output channel FIR filter length, which firmware 1.6 reduced by a few thousand taps. The pool shared across the eight output channels is 36,864 taps at 96kHz and 18,432 at 192kHz.
• Add the 'Volume Only' overview screen layout described above, with an associated Settings menu item.
• Show a profile's customised name on the display, rather than 'Profile 1', 'Profile 2' and so on regardless of what the profile had been renamed to in DSPconfig.
• Hold the S/PDIF output muted for 100ms after the receiver loses lock, rather than unmuting as soon as it relocks. A source that repeatedly drops lock no longer clicks between recoveries.
• Telemetry updates.

v1.5.0 - 18/08/2026

Version 1.5.0 is the largest release since 1.0. Major changes include controlling device settings, including master volume, audio source and selected profile directly from the GUI, live metering (for PCB revisions produced since ~Feb 2026), and, in combination with firmware 1.6, removing the per-channel limit on FIR filter length.

The internal architecture of the GUI was fully rewritten, which should make configuration of profiles a little simpler, for example, having a filter editor window open no longer blocks use of the main window. This work also unlocks upcoming work on the charts, which will include having an adjustable y-axis range and being able to show a channel's full signal chain (not just the frequency response of the filters currently being configured).

New features:

• Add a 'Device > Settings' menu item, which exposes the display brightness, display timeout, full-scale output voltage and volume mode. Requires firmware 1.6.
• Move firmware upgrades into a 'Device > Firmware...' menu item of their own.
• Show live peak and clipping meters on the input and output channels, for hardware revisions that support it running firmware 1.6.
• Flag EQ and crossover filters whose coefficients would be unstable at the precision the DSP stores them in, both on the filter card and in the chart.
• Profile configurations that would exceed the processing capacity of the DSP are now refused at the point of saving, naming what needs to be adjusted in order to fit.
• Remove the per-channel FIR tap limit, in conjunction with firmware 1.6. The eight output channels now draw from a shared pool of 30,336 taps at 96kHz (15,104 at 192kHz), and the two input channels from a shared 16,384 (9,216 at 192kHz). Previously each output channel was capped at 4,096 taps however much of the pool was going spare.
• Offer 'Save Profile' from the filter editor window, rather than only from the main window.
• Logs are now persisted to a file, rotated daily and automatically cleaned up when >7 days old. The About window shows the file's location and provides a button that opens the containing folder when clicked, and there is a new setting controlling how much detail is logged.

Fixes:

• Fix bug where removing an EQ filter was not mirrored onto the linked channel.
• Correct Chebyshev filter order and coefficient signs.
• Fix odd-order high/low shelf filters (viz. 6dB, 18dB, 30dB, 42dB per octave slopes) coefficient calculation, which was correct in 64-bit precision maths, but produced incorrectly unstable filters when converted to 32-bit for the DSP.
• Show a notification confirming that a FIR filter has been imported and applied.
• Fix swapped zero and pole labels in the Linkwitz Transform filter's tooltip.
• Fix crash in the menu bar when a device was disconnected.
• Numerous internal optimisations.

Firmware updates - version 1.6, for the DSP-8C:

• Output FIR filters are no longer limited to a maximum length of 4,096 taps. They now all share the total available pool.
• Fix bug where changing the input source would result in the profile configuration only being partially applied.
• Fix timing bug that could rarely corrupt the settings stored in flash.
• S/PDIF receiver is now fully reset on cable removal; previously it was sometimes possible for the receiver to get stuck in a state outputting constant noise.
• Numerous mathematical optimisations to further reduce the noise floor, by processing input channel biquad/FIR filter state to 40-bit precision rather than standard 32-bit.
• Output full 32-bit PCM audio samples to the DAC.
• Add a quick-select option that cycles through profiles (press up/down on the remote whilst on the overview screen).
• Add a quick-select option that cycles through the audio sources (press left/right on the remote whilst on the overview screen).
• Use a more forgiving algorithm for detecting and parsing IR remote control commands, which should widen compatibility with universal remotes.
• Add a set of extended IR remote control commands that universal remotes can use for more precise control of the unit with fewer button presses.

v1.4.2 - 04/03/2026

Version 1.4.2 contains a handful of bug fixes and minor improvements pending an upcoming larger release that will expose more functionality of the DSP over DSPconfig.

• Fix bug where copying a profile from one slot to another wasn't subsequently saving to the device correctly.
• Fix bug where All Pass EQ filters were causing the application to crash when saving/exporting a profile.
• Add confirmation dialog when trying to close DSPconfig after editing a demo device. This behaviour already exists if you try to close DSPconfig whilst you have unsaved changes for a real DSP.
• Automatically save window settings (size and position) for the filter editor window. This behaviour already exists for the primary window.

v1.4.1 - 16/12/2025

• Fix off-by-one error when determining if a new firmware version is available.
• Fix text overflow on one of the drop-down menus.
• Add a warning notification when second and subsequent instances of DSPconfig are opened and a DSP is already connected to the first instance; a DSP can only be connected to one instance of DSPconfig at a time.

v1.4.0 - 13/12/2025

• Add ability to use a 'Demo device', enabling users to try out DSPconfig without needing to plug in a physical DSP.
• Update Bessel crossover filter implementation to align with REW. Previously, we were using the phase-normalised Bessel variant, whereas now we default to magnitude normalisation. Both options are exposed in the crossover filter editor window.
• The filter editor window has been revamped. Now, rather than showing every individual filter overlaid on top of each other, the combined response of the set of filters is shown.
• Add Esc hotkey for quickly closing the filter editor window.
• Add distance measurement to 'Delay' tooltip on Output channels configuration.
• Numerous other minor tweaks and internal optimisations to support upcoming new features.

Firmware updates:

• Version 1.5: fix bug where the incorrect biquads were being selected when there was a mixture of enabled/disabled biquads.

v1.3.0 - 21/11/2025

• Calculation of Peak EQ filter coefficients now aligns with REW; previous versions of DSPconfig used a different method for calculating filter bandwidth.
• Add ability to toggle filters on and off.
• Ctrl + scroll (Cmd + scroll on macOS) when hovering over or focused on number inputs scrolls with larger increments than scrolling without holding down Ctrl.
• Default profile settings are now fully blank. Previously, output channels 1 and 2 were configured to output left and right inputs respectively.
• Upon device connection, default to showing the currently active profile. Previously, the tab for profile 1 was shown unconditionally when a device was connected.
• Add confirmation dialogs to the FIR and EQ filter editor windows when the user attempts to close the editor with unapplied changes.
• Scale the GUI smaller or larger either using Ctrl + =/- (Cmd + =/- on macOS) or options in the View menu.
• Numerous internal optimisations.

Firmware updates:

• Version 1.4: add support for quickly changing profiles with the remote. When a profile is selected, you are now returned to the overview screen, rather than just back to the menu screen. Add 'Digital Out' placeholder for the volume display when audio output is set to digital out, rather than being frozen at the previously set volume level. When saving an updated profile to the DSP, the DSP will only automatically reload the active profile if it was the active profile that was updated. Numerous internal performance and efficiency optimisations.

v1.2.0 - 07/10/2025

• Update dependencies, adding support for macOS 26 Tahoe.
• Change colour of 'Save Changes' button on the profile tabs to make it stand out more when changes have yet to be applied to the DSP.
• Add Help menu button 'Check for Updates...', which will check to see if a newer version of DSPconfig is available to download.

Firmware updates:

• Version 1.3: fix auto-muting issues with digital outputs.

v1.1.0 - 13/09/2025

• Add a 'Clear Filter' button in the FIR filter editor. Users can now delete the contents of the FIR filter editor by clicking this button.
• Remove an unused 'DAC IIR bandwidth' option from Profile Settings.
• Expose a 'Device Settings' tab, which appears alongside the 4 profile tabs, which, in turn, exposes functionality to upgrade firmware on your device.

Firmware updates: the following firmware updates are enabled by upgrading to this version of DSPconfig. If your device is currently running firmware version v1.0, the GUI will alert you that there are upgrades available upon device connection. These two updates need to be applied sequentially - after restarting your device following the first upgrade, you will be alerted to another upgrade being available.

• Version 1.1: update the backend implementation for firmware updates to allow simpler firmware updates in the future.
• Version 1.2: fix a bug where certain lengths and combinations of FIR filters on the output channels were not loading properly, causing the device to hang during initial boot or switching between affected profiles.

v1.0.0 - 06/08/2025

Initial release supporting the DSP-8C.