The FIReverb Suite™

Comprehensive audio demonstration/tutorial

Audio examples for download:

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The FIReverb Suite
  6th Edition
The FIReverb Suite™ is the umbrella name for PureVerb™ and MultiVolver™
PureVerb MultiVolver
Is a virtual room Finite Impulse Response (FIR) generator designed to create high quality natural-sounding reverberberation to be processed  with:
  • MultiVolver™ (Classic, VST or WCP)
  • Lake Huron™ or CP4™ (more of a historical interest)
  • other convolvers, such as VST-based, that can read WAV-format FIRs
Is a fast and general off-line multi-channel reverb/mix (classic) convolver
  • general design
  • convolves and mixes up to 8 x 8 channels in x out in any combination
  • allowing for up to an 8 channel reverb/mix e.g. to 7.1
  • Oct 2010 two new convolvers were added to the 5th edition of The Suite:
    • MultiVolver VST™ an 8x8 VST plugin convolver (plus separate 1x1, 1x2 and 2x1 versions)
    • MultiVolver WCP™ an NxM offline convolver
    Both using a common simple but flexible text file for the FIR setup (for MATLAB, WAV or Lake SIM FIRs), an example:

    InChannels = 1
    OutChannels = 2
    BlockSize = 4096
    Gain = 0
    Format = WAV
    01->01 = MVTST_L.WAV
    01->02 = MVTST_R.WAV


    MultiVolver™ Classic

    MultiVolver WCP™

    MultiVolver VST™
    (in AudioMulch VST host)

    • creates natural-sounding, high-density, full frequency range 32-bit FIR  reverberation using virtual microphones:
      • mono (omni or cardioid)
      • coincident stereo (cardioids)
      • AB-stereo (variable spacing, also "wide AB")
      • B-format (WXYZ)
      • 5-channel (L, C, R, Ls, Rs e.g. for natural-sounding stereo to 5-channel upmix, interactive mic setup)
      • the 5-channel implementation allows for individual microphone selection of:
        • location
        • aim
        • type (cardioid, super-cardioid, hyper-cardioid, figure-of-8, special figure-of-8+ or omni-directional)
        • setups can be saved and reused
    • uses virtual mono or stereo sources. By creating several sets of mono or stereo source responses up to 8 sources can be used together with the MultiVolver™ since it will handle the relative calibration/scaling between responses automatically even for filters created at different times
    • uses an FIR late reverberation algorithm similar to the one used in CATT-Acoustic™:
      • is rather a virtual room impulse response creator than just a tool giving reverberation
      • is based on physical principles and creates responses with a theoretically correct, with time increasing, reflection density avoiding the granularity in the tail created by many Infinite Impulse Response (IIR) algorithms
      • is based on the experience from ten years of computer modeling and auralization of real rooms
      • is used by Deutsche Grammophon together with a Lake Huron™ to enhance too dry recordings
      • was used together with a Lake CP4™ to add reverberation to the music score at the World Cup in Football (Soccer...) final at Le Stade de France, 1998 (actually CATT-VRoom, the PureVerb™ predecessor)
    • creates reverb for VR audio applications (together with Lake hardware, PureVerb™ can e.g. create all files required to run Lake AniScape™)
    • supports several samplerates:
      • 44100 Hz
      • 48000 Hz
      • 88200 Hz
      • 96000 Hz
      • 16 000 Hz (for Lake AniScape™ reverb)
    • has a straight-forward interface with settings (*in octave-bands 125 to 16k Hz) for:
      • room size
      • virtual source location
      • source directivity index*
      • virtual microphone location
      • reverberation time*
      • diffusion*
      • absorption distribution (uniform, audience or detailed*)
      • reflection incidence distribution
      • reflection density
    • optional use of the Image Source Model  for 1st order reflections
    • optionally creates responses with the direct sound excluded and the original signal can be bypassed when mixing in the reverb
    • has a large set of presets to promote realistic reverb settings and give good starting points for further fine-tuning:
      • user expandable "Generic Halls" presets where average size and RT values can be taken from actual well know halls

      • suggests reverberation time based on the volume and type of music (chamber music, opera, choir etc.) using curves of optimal ratios from literature (see fig below)

      • suggests a volume based on the reverberation time and type of music (chamber music, opera, choir etc.) using curves of optimal ratios from literature (see fig above) 
      • suggests listener (or virtual microphone) location based on the reverberation radius of the selected hall (Close, Medium, Far)

    • creates CATT PLT-files (2D plans, shaded 3D models and RT/Volume graphs) that can be viewed, printed and exported either via the included stand-alone CATT PLT-viewer or with CATT-Acoustic™ (from v7.2, also the demo version)
    • creates a new PureVerb eXtended (PVX) single-file, multi-input, multi-output, multi-microphone impulse response format that also stores a PureVerb settings-file.

      A PVX-file can be loaded by File|Open for examining the parameters used when creating the impulse responses, or to re-calculate the same basic responses after some changes in parameters. The PVX-format simplifies use of PureVerb responses in MultiVolver since only one file needs to selected for a complete set of filters. The PvxViewer shows the contents of a PVX-file, impulse responses, octave-band filtered
      impulse responses and decays.
    • optionally directly creates WAV-file format and includes a file-format conversion tool that converts Lake SIM-files to 16-, 24- or 32-bit PCM integer WAVs for use with other convolvers. Optionally creates  WAVs in WAVE-EX format
      sample PureVerb™ screen-shots
      sample 5-channel responses
    • examples of uses (all of these can be done in one step with auto-scaling):
      • mono mono reverb (1 x 1)
      • mono stereo reverb/up-mix  (1 x 2)
      • mono B-format reverb/upmix (1 x 4)
      • mono 5-channel reverb/up-mix (1 x 5)
      • stereo stereo reverb/re-mix (2 x 2)
      • stereo B-format reverb/up-mix (2 x 4)
      • 8-channel 5-channel reverb/mix (8 x 5)
      • cross-talk cancellation of a binaurally recorded stereo file (2x2, CATT-Acoustic™ >= v7 can create cross-talk cancellation filters)
      • 5-channel binaural down-mix (5x2 or 6x2 for 5.1)*)
      • n-channel Ambisonic  binaural down-mix (e.g. 4x2, 6x2 or 8x2)*)
      • B-format Ambisonic decode for up to 8 loudspeakers
        *) CATT-Acoustic™ >= v7 can create binaural room filters for various listening room configurations
    • each of the 8 inputs can have a gain to balance the mix
    • Classic: each of the 8 inputs can be any of:
      • a mono WAV
      • the left of a stereo WAV
      • the right of a stereo WAV
      • stereo WAV (left/right mix)
    • WCP: each of the inputs can be any of:
      • a mono WAV
      • a selected channel of a multi-channel WAV
    • Classic: the output channels are either one mono WAV per channel or stereo WAVs assigned to successive pairs of outputs. WCPoutput channels are either one mono WAV per channel or WAV
    • automatically handles calibration/scaling/overflow:
      • separate mono 5-channel filters for each source location can be created in PureVerb™ and they will be relative calibrated when the processing is made, no wild trial runs required to check for overflow
      • estimates filter gains and adjusts so that the output WAVs will not overflow. If it still happens in some odd cases (e.g. if the input WAVs have very low margins), it will be discovered and a safe second pass will be used
      • gives a min "margin" value on the output WAV-files (similar to that of pro DATs and similar). If the resulting margin is too high, an automatic remake can be performed
    • automatically handles delays from sources to microphones (if PureVerb™ or CATT-Acoustic™ responses are used, for imported responses initial delays should be included as initial zeros)
    • utilizes Lake's 32-bit integer SIM-file format or PureVerb PVX for for the FIR filters:
      • allows off-line tests to be made and subsequent processing using the same filters in a Lake Huron™ processor (or the other way around)
      • each set of FIR-filters can have a base-name so that fast and safe filter changes can be made (requires only one name selection)
      • can as well use measured FIRs via file conversion to SIM-format
      • PVX load dialog:

    • uses/creates 16-,24- or 32-bit PCM WAVs, optionally in WAVE-EX format.
    • uses no temporary hard disk space at all, can thus convolve any length WAVs (as long as the resulting WAVs can be fit on the output disk)
    • performs floating point convolution of long filters typically at 8x speed on an old 500 MHz PIII PC. Sample processing times with 88,000 tap FIRs (i.e. 2 sec reverb at 44.1 kHz) and 8 minutes of music
    Type of processing
    Number of
    time ; speed
    mono  mono reverb
    1 (1x1)
    1 min ; 8x
    mono  stereo reverb
    2 (1x2)
    2 min ; 4x
    stereo stereo reverb/re-mix
    4 (2x2)
    4 min ; 2x
    mono 5-ch reverb/up-mix
    5 (1x5)
    5 min ; 1.6x
    stereo 5-ch reverb/up-mix
    10 (2x5)
    10 min ; 0.8x
    maximum 8 x 8 matrix
    64 (8x8)
    64 min ; 0.125x
    • real-time 2x5 zero- or low-latency processing in hardware at 44.1 or 48 kHz , as outlined above, requires:
      • a Lake Huron™ with a minimum of  3 DSP-boards (12 Motorola DSPs) giving a latency of 160 ms (2 ms latency requires 5 DSP-boards, 20 DSPs)
      • or (for 2x4 only actually):
      • two Sony DRE-S777: 2x(11+11)=44 Sony custom DSPs total (assuming the required second DSP boards also contains 11 DSPs)
      • two Yamaha SREV1: 2x32=64 Yamaha custom DSPs total
    • has an integrated Ambisonic decode filter creator:
      • optional user-supplied shelf- and inverse speaker filters
      • energy and velocity vector graphs
      • save/load rigs or complete filter setups
    • includes a WAV-file player with single, A/B and play-list options
    sample MultiVolver VST/WCP™ screen-shots

    sample MultiVolver™ classic screen-shots
    signal flow graphs, principles
    Ambisonic decoder details
    Comes with a Tutorial and comprehensive help-files
    Many digital audio workstations today have a convolution option but which have the multi channel matrix ability, the general design, the flexibility and the small footprint of the MultiVolver™ ?  Which have a companion utility like PureVerb™ that can create natural sounding 5-channel FIR reverberation not requiring you to measure or purchase filters? In addition, the MultiVolver™ can, due to its general design, be used for many other tasks such as an Ambisonic decode, crosstalk cancellation or a  5.1 to binaural downmix.

    The FIReverb Suite™ will run under either of the following two licenses:

    1) A stand-alone FIReverb™ license (including 12 months free updates):
    Price including
    12 month updates
    Price 12 months
    further updates
    336 Euro *) 105 Euro *) *) For registered EU companies and purchases outside the EU the license can be purchased
    VAT-free, in all other cases 25% VAT is added.

    To download and test during a 30-day trial period and to download a PDF info-folder, go to the download area

    To purchase via wire-transfer or PayPal e-mail CATT     for instructions

    2) A full CATT-Acoustic™ license:

    To upgrade your CATT-Acoustic™ contact CATT or your CATT distributor

    If none of these conditions are met, The FIReverb Suite™ will run in limited demo mode only

    Note: CATT-VRoom has been discontinued and is replaced by PureVerb in The FIReverb Suite™ (old CATT-VRoom VRM-files can be read)

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