I picked this up in a bundle with Unison and Adder for $70 from ConcreteFX. I wasn't expecting to get much use out of this but I've been very pleasantly surprised to find that this is my favorite of all the additives out there.
First, I love ConcreteFX's unconventional GUIs. They're one of the few developers bold enough to abandon the hardware-style guis most developers favor. Their guis are more simpler and clearer and appear much more at home on a computer screen.
Second, this is easily the best *sounding* additive out there right now. I've been pretty disappointed with the new additive synths that have come out recently because, while they offer tremendous flexibility, they just tend to sound thin and hollow. Adder has a thick, rich sound that holds it own against a good subtractive synth.
Third, the modulation possibilities are mind-boggling. Adder includes a step sequencer, a HUGE mod matrix, fm modulation among all of the partials, a full-featured fx section, and a good randomizer. The gui is so straightforward that it isn't immediately clear how deep Adder can be, but the possibilities are endless.
Fourth, at a price around 1/3rd of the competition, Adder is scandalously cheap. It would be well worth the $200 or so other companies charge for their additives but at the current price it's a must (even more so with the current bundle that throws in Unison/Micron and Digital for no extra charge).
Documentation is somewhat sparse but adequate and the gui is very intuitive for a synth of this complexity.
Adder comes with a somewhat smaller preset library than the other additives but there are a lot of very commanding presets in the library.
ConcreteFX synths are highly underrated and the unconventional guis and low prices probably make people take them lightly. Don't make that mistake.
Adder is another excellent VSTi from ConcreteFX. As many others have ConcreteFX have tested the waters of additive synthesis with their contribution, Adder. First, Adder follows in it's siblings footsteps with a clean, two dimensional interface. Sections of the synthesizer are clearly marked and easy to learn quickly. The sound engine for Adder consists of four possible places to load data or analyzed sample data. With adder it's bet to keep the samples mono and short. You want to look for what makes the sound and upload it for conversion to additive format. This section allows you to phase, several frequency modulation controls, additive and sample effects like reverse. You don't need to use samples, in fact, on the opening screen there are several traditional (for additve) settings such as vocal, analog, bells, and other pre-built waveforms to plug into a sound. In use they are excellent ways of working without converted samples to create rich sounding timbres.
An area that may be of debate and confusion regarding Adder is its designer's choice to us 32 waveforms rather than the typical 128 or more found in other additive synths. There is a reason however. Rather than set up higher numbers of waveforms ConcreteFX has chosen to let samples or internal preset waveforms have dramatic effect as you manipulate the frequency ranges within Adder. It's very powerful and can, as additive is so capable of doing, rip apart an semblance of the original timbre, creating EBM style sounds all the way to soothing ambient timbres. Leads and basses are strong as well although the overall sound of Adder is a bit more digital than some of it's competitors. As with this new breed of additive synths, Adder is it's own idea, using additive theory in several ways and because of this sounding and behaving differently than other additive synths to date.
There are enormous programming possibilities with eight LFOs, eight variable step sequencers, a mod matrix, FM matrix, the previously mentioned sample area where converted samples become additive building blocks for timbres. There's also delay and modulation effects, a slick randomizing section - you can go from subtile to wild and that's just one section. You also have a section of the interface that allows for two multi-filters with cutoff Q and and distortion on filter 1 and cutoff, Q, distortion and ring modulation on filter 2. Above these controls are tuning and additional controls for filters and other timbre shaping. Wave manipulation is in the upper left site and controls individual volume, harmonic, semitone, volume, pitch, wave response and filters, all that can be graphically set up. In effect you have 32 oscillators to work with, each harmoncially different to start with and capable of having substantial synthesis applied to each group.
ConcreteFX took a promising additive system in Ethereal and unleased a new way of thinking additive.