Flux Bitter Sweet II, available for Mac and PC, is a dynamics processor that enables you to emphasise or de-emphasise the transient content of a signal, rather in the mould of SPL’s Transient Designer. Like all Flux plug-ins it features 64-bit floating-point processing, for up to eight channels.

There is one main control, which defaults to a neutral centre position. Turning it to the side labelled ‘Sweet’ decreases the amplitude of detected transients, while on the Bitter side the transients’ amplitude is magnified. When used on a stereo channel Bitter Sweet II also features a control to determine which elements of the signal are to be processed. In the main position, the process affects the entire stereo signal. In the Centre position, only the Middle signal of the internal M/S matrix is processed. When Stereo is selected, only the Sides signal from the M/S matrix is processed.

I have to admit I was sceptical about what this plug-in claimed to be able to do, but I tried it on a solo vocal and found that reasonable amounts of Bitter brought some life back into the vocal, although you have to be careful not to overdo it, because the starts of words and phrases can jump out. Next I tried it on a piano track, where the Sweet side didn’t have a huge effect, but the Bitter side seemed to emphasise the attack of the notes, making that piano sound very clunky.

I followed this with a bass guitar, where medium amounts of Bitter increased the attack of the bass, giving it some more ‘cut’ on the track. Conversely, the Sweet side produced a smoother-sounding bass. Finally, I turned to an acoustic guitar track on an album I am finishing up at the moment. The classical guitar was miked with an M/S pair, but I had to mic quite closely, as there was a string section playing in the room as well. When it came to the mix, we wanted to achieve an impression of more distance. My normal route is to use Waves’ Trueverb as an insert and add that sense of space with the Distance control, but on this occasion it wasn’t working as well as I would like. Adding Bitter Sweet II to the track and turning it fully over to the Sweet side allowed me to back off the Trueverb quite a lot and improved the sense of space and distance.