I can't believe this synth has no reviews, it's been around for ages. OK, so, in a word - amazeballs! I only bought it a few days ago but it's already my favourite V/A synth. I bought the non-pro version of Vacuum a few months ago. It's only $20 most places and it's a great little synth. My bandmate has had VacPro for a while and often sings it praises but it wasn't until we were working on a remix and he sent me some stems that I found out how good it really is. So I've been kind of using it for a while, waiting for another silly sale price, but I finally gave up and just bought it this week. It has not disappointed.
It's a two oscillator V/A synth with the usual trimmings. It also offers two layers, so you can double up on your sounds, like a Jupiter 8. The developers have used some fancy tube modelling algorithms or something that makes it the fattest, baddest sounding synth you can imagine. It oozes filth, great big wads of it. It's lush, it's phat, it's better than anything else I own at being a big, ol' synthesizer. Demoing the presets instantly took me back to the good old days of the 80s and 90s, when you'd buy a new synth, my ESQ-M came to mind first, and every preset sounded amazing and was full of potential for your songs. Each osc can do 4-part unison and you can "Double" the whole part, for a total of 16 oscillators per part, 32 overall.
At first glance it seems quite conventional but it's sonic range is bigger than I had expected. It does nice metallic sounds and it's hard sync has a richness to it that I really like. There are several points where you can add saturation/distortion in the signal path, which means you can make it as dirty as you like. I like. It has on-board effects that work well enough.
Everything is right there in front of you, it really couldn't be easier to use. OK, you can only see one part at a time but all the controls are there on the front panel for each part. The only part of the UI you may need to open is if you decide to use separate envelopes for each of the two filters. If you do, you need to toggle between them but if you use the same settings for each, then everything is on a single page.
Taking any of the excellent presets and tweaking them to your liking is as straightforward a process as I have ever come across. Everything is laid out logically and well labelled, it's very easy to find your way around. The GUI itself looks really cool, like a synth from the 70s that hasn't been all that well looked after. You can even add dust to the pots if you want! Even with all those controls, it manages to be slightly smaller than DUNE 2, but it doesn't look or feel crowded, none of the elements are too small and labels are easy to read. The arpeggiator is refreshingly simple - up, down, up-down and random modes with plenty of intervals and an on/off switch. There is a small, pop-up settings panel for global settings like pitch-bend range and MIDI set-up.
CPU use is very low. I can run a patch with all 32 oscillators going and the CPU meter in my host never goes above 9% in monophonic operation, and that's from a 4th Gen Core i5 in a Surface Pro 2. On a proper workstation it would hardly register. Playing overlapping 3 note chords takes it up to around 25%, which is perfectly acceptable for such a big sound. It even has an "Eco" mode which processes at a lower rate to reduce CPU use. I think it sounds fine in Eco mode and I wouldn't hesitate to use it if I needed to save some CPU cycles.
Vacuum Pro is a truly amazing analogue modelled synth. I hate using the word but it definitely has what people refer to as that "warmth" you get from classic analogue synths. Of course, none of those old things ever allowed you to stack 32 detuned oscillators on top of one another, so Vacuum Pro takes it to a level no classic hardware could hope to match. It's big and fat and fuzzy and mean and nasty and I absolutely love it.