The idea is that these LFOs are musically related. They are all set to intervals or multiples of the master frequency, with the fastest at the top, stepping down to the slowest at the bottom giving a sense of synergy between each of the LFOs. Whichever one you use feels somehow sympathetic to any or all of the others. And it's not a syncable device; you have to judge the speed yourself, which feeds into the whole idea of drifting and feeling just off the tempo but in a very organic way.

Each output generates a simple bipolar triangle shape but it is capable of being so much more. Using the CV input, you can push them into complex shapes through self-patching or using an external modulator. You can also use the input as a Track & Hold that retains a level with a high gate and releases it again when it drops. To really dive into the complexity, you can add the øchd expander module. It derives a whole raft of alternative outcomes, giving you a total of 24 modulation sources tied to that fundamental frequency.

Øchd is fascinating, beautiful to watch and experience, and would add sympathetic flavor to any patch. Just be aware of its lack of attenuation and inability to sync to your master clock. If you want specific movements and precise control, then this is not the LFO for you.

To give it its full name, this is the Batumi II 1974 Quadruple Low Frequency Oscillator. You essentially have four identical vertical modulation channels that revolve around an illuminated slider. These LFOs can be independent and drift off on their own journeys, but they also like nothing more than to sync to your clock or, at the very least, latch on to an occasional reset.

For outputs, you get a +-5V bipolar SINE wave, a "RECT" square wave and a slightly mysterious assignable (ASGN) output. On the original Batumi, the waveform at the ASGN output was set via some very inconvenient jumpers on the back of the module. This version has a button on the front that lets you cycle between triangle, up/down sawtooth, trapezoid and stepped or smooth random. A colored LED tells you which waveform is selected, but I can never remember what they are, so the ASGN output is always a bit of a surprise.

The four LFOs can run free or be conducted in various synchronized modes. In Phase mode, they all follow the frequency of the first LFO but are phase shifted either 90, 180 or 360 degrees, depending on the slider. This gives a rather delicious sympathetic throbbing effect of phase-shifted modulation. In Divide mode, they are all subdivisions of the first LFO and in Mult mode, they are multiples. These modes make the Batumi II feel very solid and intentional in your patch.

The A-145-4 Micro or slimline LFO is one of the most straightforward modulation devices on the market. Four LFOs, four knobs and four sets of triangle and square wave outputs. There are four LEDs that glow between red and yellow to show the shift from positive to negative, but other than that, it's all a bit unexciting. However, it's not the job of an LFO to be exciting; it makes other things exciting! It's compact, independent, easy to patch and useful in every scenario. For a mild bit of interest, there are jumpers on the back to swap the rate range from slow to really slow, which can take it down to an 8-minute cycle.

Meanwhile, the A-147-4 is a bit more interesting. This is a dual LFO, so don't get fooled by the "4" at the end of the name. That number refers to the version rather than any particular feature. However, the two LFOs are voltage-controllable, which means you can control the rate and the pulse width of the square wave with another modulator. You can set the pulse width by hand, giving you a nice bit of control.

You have five waveform outputs including sine, triangle, two directions of sawtooth and a pulse. It also has a reset input for either LFO that will keep the cycles in time with your tempo. Other useful features are that the incoming CV can be attenuated for more subtle modulation, and you can switch the polarity to flip the direction.

It has jumpers on the back to set the LFO range similar to the A-145-4, but this time, it can go up to audio rates and be used as a regular VCO up to about 2.5kHz.

So, for simple, affordable multiple modulators, you can't go wrong with the A-145-4. For something a little more controllable, with more shapes and in time with your system, then the A-147-4 could be just the ticket.

So, the details are that you have four channels represented by RYKs distinctive pin-prick LED meters (RYK calls them "Bars") and four knobs. RYK modules tend to have levels, and the Envy Machine is no exception. Through a couple of button presses, you can assign each channel to one of five modulation modes. These are regular LFO, random LFO, ADSR envelope, AD envelope and knob recording mode. The LEDs above the patch sockets let you know which channel you're fiddling with and the colour of the LED Bars tells you which mode. Moving from channel to channel and mode to mode will undoubtedly cause some confusion at some point, but if you can master the interface the rewards are pretty awesome.

Each mode can be fully modulated. The Bars and associated knobs transform into modulation parameters letting you allocate incoming CV to things like wave shape, level, envelope parameters, delay and rate. These parameters can be animated by recording knob movements, so you don't even have to have external modulators. This, of course, extends to the Knob Recording mode, where you can turn your twists of the knobs into cycling modulators.

There's a lot going on in the Envy Machine, and maybe it's the versatility that other people are going to be envious of. While there is the potential for confusion, the interface is elegantly designed to give you the best chance of keeping a handle on what's going on.

Otterley has some similarities to the DivKid øchd in that it has a number of related LFO outputs tied to the same speed control. However, a "Spread" control pushes the timing relationship between the four LFO outputs apart for a greater degree of modulation flexibility. The LFOs can be bipolar or switched to negative or positive unipolar, as either sine waves or square waves. Interestingly, the waveform switch has a middle position that turns it off, like a bypass, which is something I've never seen before and can be a lot of fun.

At the bottom is an additional sine wave LFO that's completely independent, with its own speed knob and output. It’s really useful as a modulator for the speed or spread of the main LFOs.

The range of possibilities lies in the Spread control. If you keep things tight, then you can have very similar sine waves that gradually drift apart, giving your modulation a very organic feel. Dialling in some distance and switching to square waves will start developing some fascinating rhythms and interplays. Otterley feels like an intelligent LFO that pushes you into creative patching. The Reset will help it maintain a reference to your main clock, but Otterley is all about the drift.

Euclidean patterns are about setting a pattern length and then dialing in the density of events within that pattern according to Euclidean algorithms. If that sounds complicated, all it really means is that you have a repeating pattern of steps and the steps fill up in a sensibly ordered way as you tune in the density.

The Length knob goes up to 8 steps, but with a button press, it can double up to a maximum of 16 steps. As you increase the density, the LFO will fill the gap between the active steps, giving you a fabulous burst of long and short cycles. Plug it into a filter cutoff and you are treated to a sort of "w-o-o-r-b, wob wob wob, w-o-o-r-b" effect, if that makes any sense!

There are a number of modes and ways to vary the outcome. You can shift the pattern steps forward or backward to hit on the right starting point for your pattern. There are multiple algorithmic options to give you differing patterns. With the Shape and Symmetry knobs, you can change the LFO waveform giving a very different feel to the modulation. There are also four outputs that you can use as completely independently configured LFOs, or have them mathematically related. There's a lot of CV control available to keep pushing the Medusa into deviation, and it even has a VCA for level control.

As you step into edit mode, the screens combine to give you information about what you're doing. Each LFO can be set up as one of around 19 waveforms. This includes all the usual subjects but also combinations, variations, noise, randomization, and chaotic behavior based on the Lorenz attractor. There are two envelope modes which you can access via the gate inputs. You can then control the waveforms' range, rate and shape to forge the perfect modulator for your modular. You can also modulate the settings of one LFO with the output of another, giving you a huge range of possibilities within the module itself.

Once you've crafted the modulators of your dreams you can save the configuration into one of 48 presets. And I think that's the point: the QV-L is not a casual LFO for spontaneous patching; it's a thoughtful, sound designer toolbox of modulation that will delight the fiddler, the engineer and the experimenter who likes nothing more than digging into the details.

It means you can have a different waveform for every single cycle if you wish, generating these fabulous bursts of different modulations. Another brilliant feature is the Multiply knob that throws in speed changes that are in time with the main tempo. The combination of controlling the wave selection and Multiply factor gives tremendous bursts of excitement and variation.

The VCLFO has two banks of wave shapes. The first bank has eight familiar waveforms you'll find anywhere, and the second has more unusual ones, including bursts and stepped modulation sequences. The chosen waveform can be modulated with the Twist control, pushing the cycles in a pulse-width-modulation kind of way. There's also a level control for attenuating the output for more subtle change levels.

The Tap Tempo function seems to be a fairly unique feature which lets you tap along to the rhythm of your sequences to match up the speed of the LFO cycles. I'm not sure how useful that is because, generally speaking, you'd probably patch in a clock, but for those moments when you want something a bit more changeable or playful around tempo changes, it begins to show its quality.