The concept of 3D audio effects — the ability to fake forward, backward, up and down movement using only a pair of stereo speakers — has been around since the mid‑1990s. Back then, digital processing was getting powerful enough to put clever algorithms into effects racks. The Roland RSS ‘Sound Space Processor’ series was amongst the more popular. They wowed music, film, TV and game sound editors with genuinely impressive demos of helicopters flying around the listener’s head.
To my knowledge, the Neuzeit Instruments Quasar is the first Eurorack module to tackle 3D audio in a similar way. It uses a combination of panning, level, frequency content, phase‑shifting and reverberation to fool the listener into thinking sounds are moving around your head in a three‑dimensional space. And it allows you to process two completely different signals. Fly one signal around your head whilst another goes in a separate direction. In Neuzeit Instruments language, a Quasar is a single unit containing the 3D positioning, reverb, and LFO settings. Therefore, there are two Quasars in each unit.
Audio signals are fed to the two Quasars via two mono input jacks, each with a gain control. They are converted to a binaural signal, processed independently first through a high‑pass and low‑pass filter, and then the magic happens. Finally, the signals are mixed — along with the dry signal — at the stereo and headphone outputs. The level of both Quasars plus the centre (dry) signal is handled by three potentiometers at the top of the unit.
Most of the fiddly stuff is done on the OLED screen in the centre, helped by two large clickable encoders for value adjustment, a smaller encoder for menu selection, and a back button. I’m generally not a fan of menu‑diving, but the structure is clear and straightforward to navigate. The two larger encoders have multicolour LED skirts that help to visualise whatever value you’re adjusting on‑screen. It can also show input levels, which are essential to set correctly for the 3D processing to work well.
A Quasar’s position in the 3D field is set using angles for the horizontal and vertical planes and meters for the distance. Distance works in conjunction with the built‑in reverb. You set reverb size, damping and amount, and the distance function will apply more or less reverb depending on the distance. Reverb is optional, but it dramatically enhances the illusion of movement towards and away from the listener.
Movement is an essential aspect of 3D processing. Simply placing a sound in a specific spot might not be enough for your brain to lock on to the illusion. There are several ways to move a sound. The first is auto mode, which works specifically on the azimuth (horizontal plane). This causes a steady circling around the listener’s head. In addition to this, each Quasar has a dedicated LFO, which can modulate any combination of the position coordinates. Having both the LFO and auto mode means you can have different speeds and directions for different planes. The LFO has seven waveforms, plus additional ‘single‑shot’ waveforms, which must be triggered by a CV signal at CV1 or CV2. Low LFO speeds work best, but higher rates can produce interesting results.
The last method of modulation comes from the two CV inputs. These can be set to modulate a Quasar’s position coordinates, reverb settings, and LFO settings. Each CV input can modulate up to four destinations with varying amounts, so eight in total. Both inputs accept voltages in the ±5V range.
There are more useful functions too. You can copy Quasar settings from one to another and copy LFO settings with or without polarity inversion (easy to set up opposing movements). Presets, which contain settings for the entirety of the module, can be saved and loaded. Some presets are included that show off what the module is capable of. For example, ‘Slow Walk’ (both Quasars slowly circling in opposite directions) or ‘Random on Trig’ (changes the position randomly every time a trigger appears at CV1). Thankfully, the module remembers its current state when performing a power cycle, so presets are just an optional extra.
Quasar is a bit of a one‑trick pony. But what a trick! ...It’s one of those modules that can add some special sauce to just about any signal...
A handy bypass option stops all processing and passes input to output — great for comparing your dry signal to your 3D signal. Then there are more esoteric options like ‘Ear Type’ (options: Human, Hobbit, Yoda, Bunny and Elephant), which mainly adjust the amount of frequency variation present during movement around the 3D space. I don’t suppose Neuzeit Instruments believes in Hobbits or expects elephants to own Eurorack modular systems (they’d struggle with the patch cables), so I suspect what will sound best will be down to speaker positioning or personal taste.
Speaking of speakers, the manual recommends that 3D processing sounds best on headphones. Perhaps this is why it’s one of the few Eurorack modules to include a headphone output. But it’s worth mentioning that it still sounds excellent on a good stereo monitoring system.
Lastly, I want to credit the excellent manual. It’s long (for a Eurorack module) at 28 pages, but it includes clear explanations, lots of background science, and plenty of tips to get the best out of the module. Bravo.
The Neuzeit Instruments Quasar is a bit of a one‑trick pony. But what a trick! Having analogue synth leads fly around your head is quite intoxicating. With the two parallel processors, you can add complex stereo processing to drones, bass lines, granular textures, or whatever you decide to feed it. I didn’t expect to like it as much as I do. It’s one of those modules that can add some special sauce to just about any signal — highly recommended.
£393
$489