Cytomic’s The Drop may just convince you that you need a stand-alone filter plug-in

The Drop is a CPU-friendly plug-in that not only emulates seven of the most famous analog synth filters, but offers modulation tools so deep it’s practically a synth in its own right—just run a tone source through it. As an analog junkie, I had to kick its tires really hard.
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Until The Drop arrived, Cytomic, had only released a single plug-in, The Glue. This was such an accurate recreation of the SSL bus compressor that not only did thousands of producers rely on it as a secret weapon, but Ableton licensed it as a permanent part of Live. So a similar buzz surrounded The Drop: a CPU-friendly plug-in that not only emulates seven of the most famous analog synth filters, but offers modulation tools so deep it’s practically a synth in its own right—just run a tone source through it. As an analog junkie, I had to kick its tires really hard. Here’s what I discovered.


The Drop’s overall design is extremely sophisticated, with all controls available from the main window. At the core are two filters—resonant highpass and lowpass, each with drive—with an elaborate array of modulation tools that combine familiarity with uncommon flexibility. In addition to the filters and modulation, there are quite a few amenities that enhance versatility. For example, the filter behavior can be further modified with Shift and Spread knobs, which allow for quickly setting up bandpass/notch configurations and radically adjusting the stereo field, respectively.

In addition, there’s a Preamp section that includes a pad, input and output gain, and wet/dry mix for the filter section. This section doesn’t directly add overdrive; instead it lets you tailor your gain staging to maximize the performance of the various filters’ saturation and overdrive characteristics.

I’ve used a lot of third-party filters over the years and The Drop’s feature set is extraordinary compared to the competition. A visualizer at the center of the interface displays both filter curves and modulation behavior, so if you start with the default and experiment you can both see and hear what’s going on with your sound.

Filter Types

Both the highpass and lowpass sections of The Drop can be switched to one of seven circuit designs. Six of these correlate directly to famous synths including the Korg MS-20, Roland SH-101 and SH-2, Moog Prodigy, Roland Jupiter-8 and Juno-6, and even the rare Oxford OSCar. Each model sounds suitably distinct and as an owner of much of the hardware represented, I can testify that The Drop’s models of their filters are astonishingly accurate. It’s easy for cynics to doubt Cytomic’s claim that The Drop’s models are true recreations of the actual circuits, but I can attest that they have truly raised the bar for virtualization.

The Drop includes independent oversampling for both real time and rendering. So you can set a CPU-friendly 1x or 2x as you work, with up to 64x for rendering your final tracks—while you run errands, because this could take time even on a very fast computer. Cytomic recommends 8x for renders and the results are well worth the wait.


The Drop’s approach to modulation may appear familiar at first, but after a little digging, even seasoned users may reel at its depth and complexity. There are two LFOs. The first is a stereo sine wave affair that includes a spread control for offsetting the phase of the modulation. It also includes options for triggering and switching between unipolar and bipolar modes. That’s pretty standard until you start playing with the Mult knob, which can multiply the LFO rate far into the kHz range—with no aliasing or glitching at all.

The second LFO includes all of the those features, but ups the ante with the addition of Asymmetry and Curve parameters, which allow for the creation of classic waveforms like square and sawtooth, as well as more unusual results like inverse exponential shapes.

The two envelopes are otherwise identical and can serve as classic envelope followers or trigger when the audio crosses a set threshold. Accordingly, the available parameters are attack, hold, and release, along with sensitivity for fine-tuning. Rounding out the modulation section are FM and MIDI tools for adding keyboard tracking, as well as FM effects derived from either the source input or a sidechain.

Geeking Out with the Designer

We asked Andrew Simper, developer of The Drop, what’s involved in modeling synth filters at the component level to get such authentic analog character. As you’ll see, his explanation didn’t spare the details.

“Every major non-linearity of the original circuits is preserved, as are the topological layouts, so each non-linearity applies to the right voltage in the right place in the circuit. Each capacitor also has the correct time-varying behavior. This is why it sounds so good and you can modulate it smoothly at audio rate. To pull this off efficiently, certain optimizations are required, so instead of full component-level models of everything in the circuit, some groups of components are lumped together into more efficient chunks called ‘macro models.’

“These macro models still yield very accurate results, but use less CPU. I reverse-engineered the [Roland] IR3109 chip at the transistor level and verified my full model by comparing it to the real thing with an oscilloscope, but I then made a CPU-friendly macro model to approximate the full model. So although the effect of each major non-linear component is modeled, this is not always done at the component level for efficiency reasons. In the end even a ‘full transistor model’ is actually a kind of macro model, since the model for each transistor could be viewed as a macro model of the underlying physics.

“I also modified the existing circuits to make them more suitable in a plug-in and DAW context, so if you directly compare The Drop with the original synths there’ll be differences—the most basic being lack of the amp stages of each synth. The behavior and curve of the resonance knob varies between synths, so I standardized the gains for the sake of consistency when switching filter models. I did go deep in matching each model very closely to the original circuits in tone, spectrum, and waveform before making any modifications, and have posted several YouTube videos showing the results.”


The Drop is a success on so many levels, it’s a little mind-boggling that it’s priced under $100. As an emulation of analog filters The Drop is a stunning achievement. It’s hard to overstate just how accurate these models really are. That The Drop actually models the circuits down to the transistors means that its sound is 99 percent identical to the real thing—and as someone with a studio full of the real thing, I’m not exaggerating. The Drop is pure magic and I’ll be using it daily for the foreseeable future. Get it now.


Unbelievably accurate analog filter emulations. Powerful and deep modulation tools. LFOs extend into the audio range. Preamp allows precise control of gain staging for optimizing overdrive. Up to 64x oversampling. Great collection of presets.


Some of the deeper features require careful study of the manual.

Bottom Line

Think you don’t need a standalone filter plug-in because your soft synths have filters of their own? Think again —The Drop is that good.

$99 street |