Review: Intellijel JellySquasher Analog Compressor & Tone Shaper Eurorack Module

I have to admit that I wasn’t terribly interested in this module when it first came out. I suppose this is partially because I have grown used to getting my compression from software plug-ins rather than hardware. There’s some great analog emulations out there, and software has a level of precision that is hard to beat. At least that’s how I felt until Danjel gave me a demonstration of an Acidlab Miami running through the Springverb into the Jellysquasher. He was able to quickly dial in this gritty, breathing, monstrous, dub techno tone from a simple drum groove and I was blown away. Toms transformed into growling synth swells. After that abrupt about-face of opinion I was eager to get my hands on one.

What Is It?

The Intellijel Jellysquasher is a single channel analog compressor and tone shaper. A compressor is a device that controls the volume level of a signal. If the signal becomes louder than a set Threshold, the volume of the signal is reduced according to a Ratio. In the case of the Jellysquasher, the threshold ranges from -40 to +17dB, and the Ratio can be set anywhere between a subtle 1.3:1 all the way to “infinity”, or hard limiter to really crush the signal. The speed that this reduction is applied is called the Attack, and the Release is the relaxing of this reduction.

A Makeup Gain can then raise up the overall volume to compensate for this reduction in level. Conveniently, the Jellysquasher has a Wet/Dry control that lets you blend the original uncompressed signal with the compressed signal to taste. This is sometimes referred to as New York or Parallel compression. It’s a very useful technique because it allows you to subtly thicken or crush a signal, but maintain your dynamic range. I’ll often perform this with sends and returns, but setting a balance with a single knob is far simpler.

Read the rest here: https://ask.audio/articles/review-intellijel-jellysquasher-analog-compressor-tone-shaper-eurorack-module

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Synthesis Essentials: All About Oscillators

Oscillators. The raw sound source that spawns the diverse range of tones and timbres spewed by all synthesizers. They come in different shapes and can be produced by a variety of techniques to make your imagination audible. If you consider the fact that all of the sounds we hear are vibrations in air, oscillators are creating synthetic vibrations that become sound once connected to a speaker. Instead of moving back and forth like a guitar string, the oscillator cycles between positive and negative voltages.

If these cycles take place between 20 and 20,000 times per second they are audible to the human ear. The rate of these fluctuations determines the frequency, or pitch of the tone, and this is tuned to produce the notes struck by the keys. We call one full fluctuation a cycle, or period, and refer to the shape that these oscillations take as a waveform. The shape of the oscillation determines the timbre or tone of the sound.

 Types Of Oscillator

Sine, Triangle, Sawtooth, and Pulse (or Square) are the four most commonly utilized synthesizer waveforms. Sine waves represent the pure tone of a single frequency, which is called the fundamental. The other waveforms have added harmonics or overtones that take place above the fundamental. This can add brightness, complexity and texture to the sound. Sawtooth waves are the most harmonically rich, because they have harmonics every integer above the fundamental. Therefore a sawtooth wave played at 100Hz will have harmonics at 200Hz, 300Hz, 400Hz and so on. Each successive harmonic descends in amplitude, or volume, by half and this cascade creates the descending sawtooth shape.

Read the rest on Ask.Audio here: https://ask.audio/articles/synthesis-essentials-all-about-oscillators

Review: Soulsby Synthesizers Oscitron

The Oscitron from Soulsby Synthesizers is a lot of things. It’s their first Eurorack synthesizer product. It’s an 8-bit digital oscillator with wavetable sampling, selectable audio engine resolution, multiple filter types, scale quantization, portamento, bit reduction and preset memory. Amazingly, they managed to squeeze all this functionality into just 14HP. This is achieved through the clever use of two knobs that also function as buttons.

You Know I Got Soulsby

The top function knob has two menu rings, and pressing it toggles between the red and green menu sets. This selects the page of parameters that the bottom button will edit. Additionally the Oscitron has knobs to control fine tuning, pulse width, filter frequency, filter resonance, and phaser offset. It provides 1v/Octave CV inputs for pitch and filter cutoff frequency, as well as inputs for pulse width, filter resonance and phaser position. There is also a clock and audio input for sampling new waveforms.

I was pleased when I opened the box to see both a detailed manual, a quick reference card, plus a cute pair of mini wood cheeks. I really appreciate it when manufacturers make this kind of extra effort. I generally prefer hands-on manuals to PDFs and I’m a sucker for wood cheeks on synths. Another unexpected discovery in the box was a little 2HP module called the Uni-Five with its own reference card. I reached out to Paul Soulsby to ask him about the Uni-Five and he was happy to give me a thorough explanation.

Paul explains : “the reason for the Uni-Five module is partly because the Oscitron is digital and partly to do with Eurorack theory! Like the Atmegatron, it’s 8-bit digital and only recognises voltages between 0V – 5V. In fact, voltages outside of this range would cause damage, but luckily it has loads of protection against this. If anything is connected out of that range it’ll just clip it to either 5V or 0V.  There’s two approaches to deal with this in the Eurorack world, where anything between -10V and +10V is fair game. I can have on-board attenuation, but the issues with that are: What kind of attenuation do I provide? Bias, attenuation, both, and over what voltage range? Or I can say: better to handle all bias and attenuation myself, so I can customize it for my own system.”

He continues: “when I developed the module, I felt that user customization was more appropriate. However, when I got to beta testing, users kept wanting to put a bipolar LFO into the filter, to make it go wah-wah-wah(!) and found the negative part of the LFO cropped off. I decided it should have some biasing and attenuation for the most common situations (5V LFO and 8V envelope). So I had the option to redevelop the entire product (which would have increased the HP and would have needed all parts prototyped again), or create a separate module, which would be much quicker, cheaper, and simpler, and could also be used with other 5V modules. So that’s basically the option I went with!”

Check out the rest of the article here: https://ask.audio/articles/review-soulsby-synthesizers-oscitron

 

Synthesis Essentials: Know Your Filters

The filter is arguably the element of a synthesizer that does the most to define its character. Words like squelchybrassycreamygritty and so on are often used to describe their impact, and reading those adjectives in this context probably made you think of a few specific synths. Perusing the various offerings in both the fixed architecture and eurorack markets presents a perplexing plethora of jargon. To make matters worse, many of these terms overlap, as manufacturers will often use different names to describe the same feature. So what makes all these filters different and how does that affect the way a synthesizer will sound?

The Basics

First, let’s brush up on the basic filter types and attributes. The low pass (sometimes referred to as high cut) filter is the most common type of synthesizer filter. As its name suggests it allows low frequencies to pass through, which can be useful for taming an abrasive top end. High pass (or low cut) filters do the opposite, letting the high frequencies through while cutting out the more rumbly tones. Mix a high pass with a low pass and you get either a band pass or a notch filter, depending on how they are arranged. A band pass allows only a narrow band of the frequency spectrum to pass through while the rest is filtered out. Notch is the opposite, filtering out only a narrow band of the frequency spectrum. A coffee filter, on the other hand, separates the ground beans from your coffee (I threw that one in just to see if you were paying attention).

There is also the more rare and mysterious All Pass filter. If everything is allowed to pass through then what exactly is filtered? In this case the entire signal is passed through but shifted in phase and blended with the original signal. At the filter cutoff point the phase shift is ninety degrees. The resulting phase cancellation causes an effect that sounds similar to a phaser or flanger. Similarly, comb filtering, which is the term for the actual result of a phaser, flanger, or chorus, is caused by blending the original signal with a slightly delayed version of itself which creates a series of notches through phase cancellation. The length of the delay determines where in the frequency spectrum the notches occur. Varying the amount of the delay time is what creates the swishy jet plane effect.

The cutoff frequency is the point in the spectrum where the filtering takes effect. Resonance is an emphasis added through feedback at the cutoff frequency. Sometimes the filter resonance parameter is labelled as Q, standing for Quality. In some cases adding resonance causes a dip surrounding the resonant peak. Some filters are able to create enough feedback that they produce a tone without any input signal at high resonance settings. These are referred to as self oscillating filters because they can effectively function as sine wave oscillators.

The number of poles, or slope of a filter determines how steep or gradually material is filtered beyond the cutoff frequency. Each pole represents a reduction of six decibels per octave, so a four pole filter would have an attenuation of 24db per octave.

While most synth aficionados are familiar with the above types of filters, they are also aware how much a low pass filter can vary from synth to synth, or even between different versions of the same model. Now that we’re on the same page, let’s take a look at some of the different architectures used to create some of our favourite filters.

Read the rest here: https://ask.audio/articles/synthesis-essentials-know-your-filters

Review: Pittsburgh Modular Lifeforms Percussion Sequencer

The Eurorack realm has no shortage of sequencer offerings, and for good reason. They can generate the pulse that drives an entire system, bring a patch to life with modulation, provide the rhythmic foundation to support your patch, or whatever else you can conceive. Because they are so critical to so many systems, and because there is such a diverse range of approach, the market still does not seem saturated. However, I imagine it’s becoming increasingly difficult for manufacturers to make sequencers that stand out by offering something unique and exciting. Pittsburgh Modular adeptly pulls this off by creating a relatively small, hugely functional, performance ready, four channel sequencer.

In the case of the Lifeforms Sequencer, the unique and exciting aspect begins with the four VCAs. The concept is that because modular systems are generally adept at producing noisy signals (both intentionally and unintentionally), why not shape that raw noise into percussion rhythms? Each channel of the LPS has both an input, output, and an envelope output with control over Decay. The envelope out can also work as a basic impulse similar to a kick drum. This arrangement offers a great deal of flexibility because you can rhythmically gate a noise source, trigger and sync with other modules, send percussive envelopes, generate kick tones, or any combination of the above from one place. Combine that with the ability to save 32 patterns and you have a powerful little sequencer indeed.

Read the rest here: https://ask.audio/articles/review-pittsburgh-modular-lifeforms-percussion-sequencer