Decade Bridge Releases “Speculum Free” Comb Filter VST/AU Plugin

Decade Bridge has introduced Speculum Free, a freeware comb filter and delay effect in VST, VST3, and AU plugin formats for compatible digital audio workstations on PC and Mac.

Speculum Free is a modulation tool capable of operating as a comb filter or as a standard delay effect. The only difference between the two operating modes is in the scaling of the Delay Time parameter. Its range is between 0s and 0.02s while in Comb Filter mode, whereas the maximum value is increased to two seconds while in Delay mode. Obviously, the developer’s idea was to allow for more precise adjustments when using the plugin as a comb filter, as even the smallest of delay time shifts will result in a different sounding timbre.

The plugin also features a built-in low-pass filter with cutoff and resonance controls. The filter is placed outside of the feedback path, so it only affects the signal before it reaches the delay stage. In other words, the feedback signal is not affected by the filter. As a result, the effect is easier to control when working with longer feedback times (to prevent resonance buildups and excess volume) but also somewhat limited as a creative sound design tool. That said, Speculum Free can cover a range of effects, from basic delay and comb filtering to flanging, phasing, and more.

Sadly, Speculum Free doesn’t feature any modulation sources so the user will have to modulate the parameters via automation or using external MIDI sources. The developer acknowledges this by naming one of the presets as “Automate Me”. Indeed, Speculum Free would become a far more versatile tool with the addition of even a simple LFO module, which is why we’re hoping to see it (or some other modulation source) included in a future iteration of the plugin. Either way, even without internal modulation sources, Speculum Free is worth downloading if you’re looking for a plugin to cover basic comb filtering, flanging, phasing, stereo delay, and similar FX tasks.

This freeware product is Decade Bridge’s first foray into the VST and AU plugin world, but it’s far from being their first piece of audio software. The developer has released a very capable tone generator app for Android called ToneBars and several ZX Spectrum 16k/48k programs (yes, music apps for the old ZX Spectrum home computer!).

Speculum Free is available for free download via Decade Bridge (15.9 MB download size, ZIP archive, 32-bit &64-bit VST/VST3/AU plugin format for Windows & MacOS).