Hi
@Keith_W Just some updates about Hang Loose Convolver (HLC).
Max output channels is 16 on Windows as it is a VST3 limitation soon to be fixed by Steinberg. On the Mac I have folks using 32 output channels with a max of 36 currently. Note I say output channels as there may be many more convolution channels. For example, while a 7.1.4 Dolby Atmos is 12 channels, it does not account for that there may be bass offloading for each of the speakers to the sub(s), which doubles the number of convolution channels required. Note this can only be accomplished by using the industry standard "config" file specification discussed later below.
VB-Virtual Audio Cable, VB-HiFiCable ASIO Bridge, ASIO4ALL, ASIO Link Pro, etc., covers any WDM and/or ASIO lopback configuration on Windows, BlackHole on Mac and ALSA loopback on Linux. All are free virtual loopback drivers and takes a minute to install and work reliably. However, if one has a "Pro" interface, then h/w loopback is the best approach.
HLConvolver comes with HLConvolverHost which can host any VST3 or AU plugin on Windows, Mac and Linux and can be used as a standalone application.
While the number of Filterbanks is 6, one can save that as a preset. Each preset has 6 Filterbanks x as many presets as one wants. With a few mouse clicks one can have access to dozens of filters.
While it is sort of mentioned, HLC automatically calculates the gain of the loaded filter so that all filters, regardless of their individual gains, are all at the same level and the same level as the bypassed signal. So when switching filters they are all level matched. A key consideration when comparing filters.
As you mentioned, switching filters on the fly is instantaneous and glitch free. This also includes switching between minimum phase filters whose filter peak starts at sample 1 and linear phase filters whose filter peak starts anywhere but sample 1 (e.g. may start at sample position 32,768 in a 65,536 tap filter). So when switching between a minimum phase filter with no delay versus a linear phase filter with hundreds of milliseconds of delay, the switching is instantaneous with no audible delay gap.
You may want to break out which convolvers support what is recognised as the industry standard convolver "config" file:
https://convolver.sourceforge.net/config.html This specification allows one to do, amongst other features, input and output scaling and summing, which are important configuration parameters for sophisticated convolution projects in which without the power of the configuration file, there would be no solution. As a side note, DRC/DSP packages like Audiolense, Acourate, and Focus Fidelity Designer automatically generate this industry standard config file that one can simply load in HLC in 2 seconds and have working.
You may want to identify if the convolution engine is a 0 millisecond latency engine. Some convolvers have their own inherent delay to account for. With a 0ms latency convolver and minimum phase FIR filters (and minimum phase digital XO's) one can watch
Dolby Atmos movies with convolution and no lip sync issues.
Perhaps listing convolver capabilities of being able to automatically load the matching sample rate filter on the fly when the source (i.e. host) sample rate changes.
You may want to identify which convolvers are offered as a "plugin" like as VST3 or AU plugin. This is usually a requirement on the music production side with folks using DAW's.
PS. If may be useful testing convolution engines as some have issues like
Roon.
As an aside, I am surprised you have not listed Bernt's Audiolense Convolver...?
Keith, if you need more than 14 days to eval, please let me know
