in FIR Designer & FIR Designer M (version 4 +)


in FIR Designer & FIR Designer M

(version 4 +)

Create custom filters & presets, then hear how they sound before export.

Listen to your custom filters & presets in realtime

Compare three presets simultaneously

Audio inputs: choose a file or listen live

‘auditionDSP’ is a digital signal processor & audio player built into FIR Designer & FIR Designer M, allowing users to LISTEN to the custom processing, rather than relying solely on visual plots.

Within FIR Designer, auditionDSP runs one channel of processing as either mono or stereo. Within FIR Designer M, it runs six distinct processing channels. In both products, auditionDSP can run processing for up to three loudspeaker presets simultaneously in real-time, with live switching between presets enabling easy comparisons. Use it to audition, develop & perfect custom loudspeaker filters and presets, without the need to export data to an external hardware processor for playback.

Listening to custom filters and presets pre-export offers offers huge advantages over working solely with visual plots during during the design & development process. Comparing filters audibly allows them to be quickly & easily perfected, ensuring that they’ll sound right first time when loaded into an external amp or processor.

Users can choose their preferred audio input when using auditionDSP to listen to filters. Test signals or music both work and can either be used live (from an external source) or from a loaded WAV file.

auditionDSP is powered by a dynamic built-in DSP engine which utilizes floating point processing & includes low-noise state-space biquads for IIR filters. Each processing channel block – delay, IIR, FIR – runs at the intended sample rate (from the preset) & high-quality sample rate conversion is used between blocks that have different sample rates.

More than just an audio player, auditionDSP allows you to use any PC or Mac as a virtual single (stereo) or multi-channel audio processor.


Poorly designed processing could cause high sound levels through your loudspeaker, which (depending on amplifier size) could lead to loudspeaker damage. Take care in setting the gain structure through your audio device & amplification to minimize the potential for problems.


Comprehensive overview of the multi-channel version of auditionDSP.



These instructions use FIR Designer M screenshots;  using auditionDSP within FIR Designer is a near-identical process.

To run auditionDSP, you will need a professional audio interface capable of duplex audio – e.g. from RME, MOTU, Presonus and Focusrite – and the audio interface drivers installed. (auditionDSP uses Core Audio on macOS and ASIO on Windows.)

Running auditionDSP

  • Launch FIR Designer M version 4 and load, or create, a system (FIR Designer users load/create a project rather than a system).
  • From the “auditionDSP” menu, select “Launch.”

  • The auditionDSP window will appear. Select your audio device and sample rate; either 48 KHz or 96 kHz.

  • auditionDSP can run up to three presets in parallel. Select one of the preset buttons, then select FIR Designer M window from the drop down.

  • Select “Get Settings.” This pulls the preset from the select FIR Designer M window and into the auditionDSP “Input” and “Output” processing blocks. The blocks display the sample rate, gain, polarity, delay, IIR filter details and the FIR filter details.

  • Now
    • select the WAV File “Load” button to load WAV file for playback,
    • for each output channel, select “File” and the which WAV file channel to use,
    • for each output channel, select the audio device output channel,
    • un-mute the outputs and turn the “Out Gain” down low, then
    • press “Start.”

  • On macOS, when auditionDSP is run for the first time, the following window appears. Press “OK.”

  • Now playback and processing is running. The green meters show peak in the middle and RMS either side.

Input selection, input gains, mutes, output channels, presets and output gain can all be used/adjusted during playback.

Once you’ve got used to how it works, tell us what you think! (We’d love your feedback).