Studio Electronics Boomstar 4075 by Synth80s
I recently picked up a Boomstar 4075. Since there don't seem to be many Boomstar reviews floating about, I figured I'd offer my take after the first few days of heavy tomfoolery with my shiny new analog plaything. First, some ground rules:
1) I have no connection with Studio Electronics (though I admire their product lineage) or any other audio/music company. Oddly, I've noticed that positive internet reviews sometimes elicit cries of "shill" and critical comments can lead to consipracy theories about manipulative competitors. I assure you that I am neither.
2) I don't claim to have exercised the Boomstar to its full extent, but I've been working with synths of all varieties for longer than I care to mention, so I find that I can usually get to the heart of most instruments fairly quickly and suss out their core character.
3) I've only used the Boomstar as MIDI-driven synth module, so I don't have any insight to share about the CV control features or external audio filtering capabilities.
4) This review is written from the viewpoint of a massive synth enthusiast and my opinions are simply...well...MY opinions. Some of them may even be rooted in fact, but let's not get carried away. I will say that I generally try to stay positive when evaluating others' creations because I believe too many people today are quick to trash something for what it's not, rather than spend the time to find the value in what it is. I also believe that the long reach of internet anonymity only serves to reinforce this trait. Stepping off soapbox now.
5) Please pardon the length of this review, but I really dig synths, dammit (!) and, again, there seems to be a lot of mystery about the Boomstars.
Now, on with the show...
The Physical - The Boomstar design is business-like, especially the 4075 in its battleship grey regalia, and the build and component quality are top notch. The case is all metal with a reassuring solidity, and the finish and legends on the face are flawless. All the knobs and switches are quite sturdy -- the pots have minimal wiggle and the toggles switch with a satisying click. I must admit that the heavy "thunk, thunk, thunk" emitted when switching between octave values on the 2 VCO range selectors is deeply gratifying. Yes, I have a problem. Somewhat surprisingly, the 4 rows of large pots only require a light touch while the bottom row of mini-pots require a bit more effort. Design-wise, the Boomstars may not have the visual panache of some Moogs, etc. but there's no faulting the overall construction and utility. Lastly, it's worth noting that the Boomstars offer a fair compromise between control and size. The unit is pleasantly compact and offers well-spaced controls without feeling cramped.
The Oscillators - While not unique to the Boomstar line, the ability to combine 2 waveshapes on OSC 1 offers laudable flexibility. When dialing up a bright sawtooth bass, for example, it's helpful to blend in some sine wave for added girth. Similarly, combining the sawtooth and square waves on OSC 1 can lead to additional sonic variety when the VCA is pushed into distortion, especially when a little PWM is mixed in. It's notable that you can do a lot of damage with OSC 1 before OSC 2 is pressed into service as an audio source. This is especially useful if you choose to reserve OSC 2 as a 2nd LFO or other modulation source. Again, quite flexibile (a common Boomstar theme). Like any true synth geek, I often gravitate to the lovely beef that two slightly detuned VCOs can offer, and the Boomstar doesn't disappoint. More on the sound below.
The Filter - This is obviously the main Boomstar quandary. Even if you've decided to buy a Boomstar, which filter to choose? It was difficult enough with the 4 original choices, then SE recently added to the vexation by offering 2 more options. For my part, I found that the Moog, 303 and SEM filters represent sonic territory that can also be found elsewhere, but the ARP sound is relatively uncommon in modern products. That thought, followed by repeated listenings to SE's recent filter comparison demos sealed the deal for me, though I briefly flirted with the idea of the CS-80 model as well. Back to the 4075 filter: at first glance, it's straightforward and sounds much like any quality analog filter should, though it doesn't immediately blow your socks off with character. But as you start to eek into mild VCA distortion, you experiment with the feedback circuit, and you play with the modulation options, the plot thickens. The filter is highly responsive to interactions with other components and it doesn't hide away or get muddy when pushed. It's worth noting that adding resonance thins out the sound relatively quickly. I don't mean to suggest this as an issue, merely a characteristic of this and many other filter circuits where resonance attenuates the signal to a greater degree than some other filters.
The Envelopes - Admittedly, I haven't taken much advantage of the more flexible options offered by the 2 envelopes (inversion, looping, etc.), but they strike me as a solid "ADSR Plus" design. Nothing fancy, but they can be very fast when you want them to be, and that's one of my absolute requirements for any keeper monosynth. As others have pointed out in the long-running Boomstar thread on Gearslutz, many of the analog pots blow through much of their meaningful values within a small range of physical travel. Nowhere is this more evident than in the envelopes. The envelopes are highly shapeable, but you really have to fine tune them to apprecaite their flexibility. For synth programmer types like me, it's just an adjustment that needs to be made, though I could see it is a potentially bigger issue for live tweakers. Not to speak for SE, but I believe they noted in the other thread that this is an artifact of the high quality analog pots they used (as opposed to encoders on a digitally-controlled analog synth). It's not a big issue but I'll come back to this later. Suffice to say the envelopes are solid though it may take some time to get the best of them.
Cut the crap! How does it sound? - Individually, the raw oscillators start out with a lean, modern tone. Not tubby and not thin, but right in the middle. With the filter wide open, the high frequency content is ample, and that may lead you to believe that the VCOs lack girth. But as you work the waveform options, employ the filter and push the VCA a bit, the Boomstar toughens up nicely. Having played with many monosynths over the years, I'd say the Boomstar reminds me most of a Pro One, albeit less brutal overall (my former Pro One was a beast of a machine -- nothing like it before or after IMO). Other reference points? The 4075 has a little Moog-ish squeal to the filter, but the overall sound of the unit is sharper, leaner and more modern than the recent Moogs I've played -- quite different really. Compared to a Bass Station II, the Boomstar is similarly clean when everything is kept simple, but the sound is finer and a bit harder overall (the BS2 has more of the trademark Roland roundness and softness to the sound). It's difficult to succinctly describe the sound of any instrument that's deeply flexible, and that holds true for the Boomstar. I believe its true character shines through when the VCA is pushed, even without the overdrive circuit engaged. The synth engine is deeper than it initially appears and it takes a while to figure out how 1 + 2 + 3 adds up to 11.6, but that's the best way I can describe it. Which leads me to...
What else do I need to know? - Every instrument holds secrets that you can only really uncover when you spend some hands-on time with it. On the Boomstar, that secret is subtlety. With the relatively fine controls and high-resolution circuits, the real treasure is tweaking the last 5% of any patch to get it just right. I've worked with synths that were frustrating simplistic and I find the Boomstar to be the exact opposite. It requires patience, but if you experiment with the modulations and interactions, you can surprise yourself. From memory, I'd say I've spent more time developing each sound on the Boomstar than I usually do on other monosynths, but the level of effort required has a ratio of about 80% fun to 20% tedium.
What would you improve? - I really only have 2 constructive criticisms, neither of them major. Without rehashing the subject, I think the Boomstar experience would be improved if the slightly touchy pots were more linear. I don't claim to know how this could be accomplished (and I must add that I've experienced the same feel with other analogs), but I think the fine control required to get the best of this synth might initially throw some people who were raised on more linear digital controls. Secondly, I would have preferred that the Boomstar's pots be adorned with knobs that allow the values to be more easily discerned. The early product photographs showed some units having metal-topped pots with more obvious value indicators than the all flat black pots that made it into production. Clearer knob cosmetics would be helpful when operating the Boomstar in a dark environment, and they would make patches easier to capture with camera pictures. It's a somewhat picky point, of course, but I do wonder why the originally shown pots weren't used or offered.
Summary - The Boomstar is all about quality and flexibility. The clarity and fineness of the audio circuits and the complex routing capabilities combine to form a truly powerful synth. Like any synth without patch memory, it may not be as immediately gratifying as other instruments on the "showroom floor," but it rewards your patience and it has the power to surprise you in positive ways. My best advice: if you have an opportunity to demo a Boomstar, allow yourself at least a couple hours of focused tweaking and prepare to dig into the intricacies of the controls to get a sense for its true sonic capabilities. Nice work, Studio Electronics!