FireSonic claim "this unique sonic exciter is a plug-in like no other."
Available in all the popular Mac/Windows plug-in formats, FireMaster has a similar layout to FireSonic's FireCobra enhancement plug-in but, using 64-bit audio processing working at sample rates of 192kHz and beyond, this one is designed to add a more subtle polish to either individual tracks or complete mixes. It uses licence files for activation, which allows you to run the plug-in on multiple computers. The CPU load is surprisingly light too, so you can use FireMaster on multiple tracks if you wish, without over-taxing an average computer.
FireMaster comes with a range of presets for different applications, and the designers suggest that picking a preset and then adjusting the amount added may be all you need to do — but with so few controls it's also very easy to fine-tune the processing yourself, in which case the presets provide practical starting points. The processing is 'parallel', which means that the dry signal is mixed with the processed signal to achieve the desired effect. The wet/dry balance is adjusted via a large knob at the top centre of the fully resizeable GUI, and I found that I could usually get away with adding quite a lot of 'wet'. Sliders set the levels for the input and output, and there's associated metering to warn of clipping.
The designers don't give away too much regarding the finer details of what's going on inside the algorithm, but the key processes appear to include some form of parallel compression (controlled via the Depth knob) and tube-like saturation (via the Color knob). However, the Color knob obviously adjusts more than just saturation; you hear a flanging sound as you turn it, which suggests there's some time-manipulation involved too. Two further controls adjust Bass and Air, though I suspect these stray beyond conventional EQ because the processes also seem to help emphasise the stereo nature of the material. Bypass does as you'd expect, and is designed to work without introducing clicks or timing glitches — so it can be automated.
On a full mix, the processor adds weight without muddiness and delivers a very polished sound that doesn't sound aggressive or overdone unless you max out every control. It also seems to strengthen the stereo image. On individual tracks, FireMaster is very effective for firming up and adding detail to bass or drum parts but it can also be used to add focus to vocals, acoustic guitar and percussion in a natural-sounding yet addictively appealing way. There's definitely more to this plug-in than the straightforward control set might suggest, and given there's a free 15-day demo I'd thoroughly recommend giving it a try.