Eurorack Multi-LFO Module Review

Ever since I received my Mordax DATA, I've been preoccupied with looking at the output of my eurorack modules. I always wanted to see what my oscillators were doing, but the output of my various modulation sources have really piqued my interest. This review is a comparison of LFOs.

To distinguish my consideration of what an LFO is. In general - a Low Frequency Oscillator is a module that generates a continuous oscillating control voltage that is primarily used to modulate other modules. The acronym "LFO" has kind of taken on a life of its own - as many LFOs are used well above "Low Frequency".

There are two common types of LFOs - identified by their controls:

• Oscillator Type. Has Frequency or Speed control. Often presented as a sound source, VCO or DCO, with the option to slow it down below audio rate. Eg. Xaos Batumi.

• Loopable Envelope Type. Has controls for rise/attack and fall/decay time. Eg. Make Noise MATHS.

My criteria for this review is for modules that provide two or more LFOs. It doesn’t have to be a dedicated LFO module, but the idea is that you should be able to provide more than one modulation - ie. two different signals of output. I'm also going to delve into the economics of LFO modules with simple details like cost per LFO, and LFOs per HP - but you can extend value for modules that serve more than one purpose.

When deciding on an LFO bank, here are the questions you should be asking:

• Do I need more than a triangle wave?

• Do I need more than the standard waveforms (TRI/SIN/SAW/RAMP/SQR)?

• Is having more features, or being multipurpose worth paying more per channel?

• Do you require specific CV control? Per LFO? For additional parameters?

• Do you require having a 10vpp bipolar output (preferable), or can you make do with 5Vpp unipolar (less desirable)?

• Is real estate in my rack at a premium?

For this comparison, the modules I considered - in no particular order - include:

• ALM Pamela’s NEW! Workout

• Instruo Ochd

• Intellijel Quadrax

• Intellijel Tetrapad

• Mutable Instruments Stages

• Mutable Instruments Tides

• Xaoc Devices Batumi

• Xaoc Devices ZADAR

• 2HP LFO - Four of them, just for comparison.

• Make Noise MATHS

• 4ms Spherical Wavetable Navigator

Not to pick on Make Noise for MATHS, I included 4ms Spherical Wavetable Navigator (SWN), because it shows that buying MATHS specifically for LFO duties is a severe waste on money and rackspace. I really love MATHS - it’s analog, it does a multitude of great things (I miss having one) - but, so many people buy it just to do AR and LFO duties. And for that it’s a waste.

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I own 6 of the tested modules, with Instruo Ochd on order (I can't wait!!). And I can’t say that there is a clear winner. Depends what you are trying to do, what you do most often, and what sacrifices you are willing to make.

Here is my opinion on a few LFO subjects - you may disagree.

Output Signal

For me, the ideal signal to work with is 10Vpp bipolar. This means the oscillation goes up and down from -5V to +5V. I can still work with a unipolar signal - but for some CV inputs, I need to use two channels of my attenuverter to make it -5V to +5V bipolar, as the module can’t handle a 10V input. 8Vpp is workable. But 5Vpp is quite limiting. For some waveshapers and filters, this means you can only get half of the full range of modulation.

Best Modules here: Most of them. The unipolar ones are Stages and ZADAR. But the worst here is Pamela - it can only do 5Vpp unipolar.

Speed Range

LFOs kind of fall into four ranges: nearly unnoticeable; slow and sweeping; vibrato-like effects; or screeching FM - basically the sound of driving a VCO with another.

The middle two are most common for my purposes. A few LOFs I’ve tested can go on for hours - Batumi and 4MS SWN LFO’s can go for a day per cycle! Useless for me.

The sweet spot is an LFO that can go from a minute or so, to 100Hz. Anything faster than that - and I’ll use a VCO.

One note about clocking - this is different than having a trigger input. Having a trigger input just resets the cycle, it doesn’t stretch the cycle to fit.

Modules that feel like they have a great and controllable range: Ochd, Quadrax, Pamela, Zadar.

I always found MATHS to be hard to manipulate because of the rise and fall knobs.

Quadrax and Tetrapad would be better if they could go slower - but they are the easiest to use and control.

Stages is really easy to use, but it can’t slow enough without going into multiple channels - and then it’s like using MATHS.

Waveforms

I typically prefer sine waves. They are more difficult to sense. Unlike a triangle wave, they have no abrupt top or bottom.

While I like the economy and concept of Ochd - I really wish it was 8 sine waves rather than triangles.

ZADAR can do anything you want… except one thing. A sine wave. Wave E2 is almost a sine, but it has a strange delay at the top and bottom of the cycle. For other types of motion and effects Zadar dominates.

Usability

By far - Ochd wins here. One control. 8 different outputs. Bang. done.

Stages, Quadrax and Tetrapad and really easy to use and dial in. LFO mode, Patch, adjust waveform and speed.

ZADAR is very complex. So it takes some forethought to use it. A bit of menu diving to set it up as an LFO; but then the four knobs are intuitive.

Summary

In general, I prefer the controls and output of a dedicated LFO function - speed knob (rather than rise/fall), and a bipolar output.

If I were to pick my top three - Ochd for its analog-ness and economy; ZADAR for its limitless functionality; and Quadrax for its amazing and easy-to-use functionality.

Dishonourable Mention - sorry to the budget-sensitive folks… the 2HP LFO. Yes it’s only 2HP. And it can do 30 seconds up to 152Hz. And it has more than 4 standard waveforms.But it’s false economy: To actually get 4 LFOs with different rates, the cost per LFO is more than buying the 4ms SWN, it only does 5Vpp unipolar, and you need to have 4 spare power headers in that little case.

Pamela is also only 5Vpp Unipolar - but as a clock divider, and Euclidean trigger generator - it’s the king (actually… Queen).

I'd like to add to this list/test. Some modules I'd like to get on my scope:

• Malekko QUAD LFO

• 4MS Quad Pingable LFO

• Doepfer A-145-4, A-143-3 Quad LFO, and the A-143-4 (giant!)