Relab QuantX: The Master of Space
by Diogo C
23rd November 2023
Sponsored by Relab
The early 1980s were a busy time for effects processors: it was the dawn of the digital age and sonic possibilities seemed endless compared to what analog do. On the other hand, the components of that time had obvious limitations, which pushed designers to find creative ways of working around them. The Quantec Room Simulator QRS is a prime example of this era, where a new concept for reverbs and a clever implementation came together on a charming unit that made the best out of the chips available at the time.
The Room Simulator
First introduced to the world in 1982 by its creator Wolfgang Schwarz at the Audio Engineering Society (AES) Montreux show, the Quantec “QRS” had one single yet ambitious goal, which is to emulate the natural resonance of a sound source such as the human voice or musical instrument in an acoustic space. In short, it was meant to be a “Room Simulator”, hence those two “RS” letters in its name. The original brochure helps to elucidate its inner workings:
“The Quantec Room Simulator is a new technical concept that enables emulating the acoustical behaviour common to spaces of any volume or size, so that acoustical impressions ranging from a tin can to a columned cathedral may be synthesised and created at fingertip command.
Contrary to standard reverberators, the Quantec Room Simulator enables the reproduction of the selected space’s inherent resonances, which are a function of it’s basic enclosed volume, in that their density and distribution are precisely established.
In conjunction with the legendary “first reflection” this is the effect which enables the ear to establish spatial volume and size of a percepted room.”
The original Quantec QRS - picture courtesy of Reverb.
The QRS was able to create seven room sizes from 1 to 1 million cubic metres in a very realistic way, with reverberation times ranging from 0.1 and 100 seconds. It was a perfect fit for enhancing studio recordings which were often ‘dry’ and lacking ‘room’ sound. Although it only had eight parameters and lacked more complex controls like its competitors, (Like the Lexicon units of the time), it had a peculiar sonic signature that immediately captivated music professionals. This is mainly because of the way it processed the sound, relying on mathematical models that creates the resonance of a sound on a given space instead of trying to simulate what’s happening when a sound hits such space. Its unique resonator-based approach and independent first-reflection level adjustment lead to a studio reverb that is creating an effect that sounds more natural and less metallic, which was a frequent criticism of digital reverbs of the era.
Beside the main reverb, the QRS featured an extra effect: Enhance. The Enhance effect can be considered as a different flavour of reverb, but one where the sound is distributed differently than the regular program, featuring a “reflection cluster” that consists of reflections with equal strength that is followed by a decreasing set of reflections.
Illustration of the enhance and reverb programs taken from the Quantec-QRS Manual.
However, despite its success and cult-status it acquired, it’s not all rainbows and unicorns, the Quantec had some drawbacks: the limited availability and hefty price made it quite an exclusive unit, and only the upper echelon studios, or people that could afford to hire one, were able to enjoy its fabulous sound. Fast-forward in time, right now there are only a few of those units left, and finding one in mint condition is a hard and often fruitless endeavour, so it’s a classic case where having a faithful emulation in plug-in form is something most of us would welcome.
If there is one company capable of delivering such a plug-in, that company is Relab. After successfully bringing the legendary Lexicon 480L reverb and Maselec MEA-2 equalizer for our DAWs, they have more than proved themselves to be one of the leading companies when it comes to making fully accurate emulations of hardware gear. Relab has deep expertise when it comes to reverbs, and besides the 480L they have also created Sonsig Rev-A, an innovative algorithmic reverb plug-in that delivers superb quality without overwhelming the user with overly complicated controls, and the company is also working on an emulation for the iconic TC Electronic VSS reverb, which is currently in its last stages of development and on public beta, so there’s no better candidate for this job of bringing the Quantec QRS to the 21st century.
The QuantX Plug-In
It starts with a picture-perfect interface but underneath there is an extensive analysis and coding work to recreate the original unit in all its glory - including its imperfections and even its obscure quirks. According to Relab, “heat-induced behavior changes, including clock fluctuations due to temperature variations, had to be taken into account. With a ±3% stability factor, these fluctuations significantly impacted reverb coefficients, which was vital to recreating the true feel of the original.”
This time around the company obtained three original Quantec QRS units from the United States, Japan and Germany, with the latter serving as the benchmark due to its pristine condition, (lower noise floor and overall superior performance etc). A custom-built MIDI interface was created especially for it so the controls could be set and recalled with total precision, allowing Relab’s machine-learning tools to analyse and capture each and every parameter change, thus resulting in a data set that surpassed millions of data points, which lays the foundation for the QuantX plug-in.
The trademark Relab dual-engine architecture also makes a comeback here, with one engine solely dedicated to the main reverb and a second one solely for the Enhance effect. This ensures that both effects have uncompromised sound quality that is truly faithful to the original hardware, and it allows users to control each one separately for seamless control of each stage.
The QuantX plug-in also takes the QRS to new heights with enhanced bandwidth and Relab’s proprietary Advanced Chorus Ensemble (ACE). As those familiar with vintage reverbs might suspect, the original unit from the 1980s had to compromise on its operating bandwidth due to the converters of the time, which were limited to sampling rates that are lower than what we enjoy today - and this is part of its charm. On top of that, the Quantec also featured an analog low-pass filter rolloff around 8 kHz besides the 10 kHz bandwitdh (20 kHz sample rate) of the digital algorithm, which softens the top end for a more smooth sound. This is present on the plug-in, but it also opens up the possibilities by offering extended filtering options from 4 kHz to 16 kHz, and according to Relab these roll-off points were carefully chosen in order to “follow a specific geometric sequence (Renard Series), which, we believe, is what the original designers would have used had they ever chosen to enhance the original hardware”. Furthermore, these are not the usual low-pass filter, but a recreation of the converter’s sample rate and analog filters from the hardware, with all its resonance peculiarities.
The Advanced Chorus Ensemble takes modulation to a new level, with eight voices running in series on the dual-engine for a total of sixteen voices that were hand-tuned with a custom tool (pictured above). Before anyone asks, this tool is not available to users and was used only for development purposes so Relab could really zoom in and put together a modulation layer that is deeply intertwined with the reverb - all the user has to do is dial the modulation knob and blend in the desired amount for a rich-sounding effect that doesn’t feel dislocated from the reverb. Values below 10% can provide subtle movement and chorusing, whilst higher values can be used to increase the richness and density of the reverb.
The interface has also been refined and optimised for modern computer screens, offering resizing options from 75 to 200%. The original unit relied on buttons for most operations, and these have been replaced with knobs for a more fluid workflow - we can all agree that clicking on “+/-” and numeric buttons with a mouse simply doesn’t work well. The central encoder for reverb time, volume sliders and metering were all preserved as they’re certainly in the “if it ain’t broke don’t fix it” category: taking lessons from the past and building upon them is definitely the spirit here, and after the huge success of the LX480 plug-in, it’s safe to say that Relab has brilliantly future-proofed yet another classic reverb.
The Relab QuantX plug-in is available right now as AAX, Audio Unit and VST for Mac and Windows. For a limited time, you can get the QuantX plug-in for $149 (regularly $199) or pay over time with 3 payments of $49.99/month. A 7-day fully functional trial is also available.
For more information, demo or to buy, please visit: relabdevelopment.com
The early 1980s were a busy time for effects processors: it was the dawn of the digital age and sonic possibilities seemed endless compared to what analog do. On the other hand, the components of that time had obvious limitations, which pushed designers to find creative ways of working around them. The Quantec Room Simulator QRS is a prime example of this era, where a new concept for reverbs and a clever implementation came together on a charming unit that made the best out of the chips available at the time.
The Room Simulator
First introduced to the world in 1982 by its creator Wolfgang Schwarz at the Audio Engineering Society (AES) Montreux show, the Quantec “QRS” had one single yet ambitious goal, which is to emulate the natural resonance of a sound source such as the human voice or musical instrument in an acoustic space. In short, it was meant to be a “Room Simulator”, hence those two “RS” letters in its name. The original brochure helps to elucidate its inner workings:
Contrary to standard reverberators, the Quantec Room Simulator enables the reproduction of the selected space’s inherent resonances, which are a function of it’s basic enclosed volume, in that their density and distribution are precisely established.
In conjunction with the legendary “first reflection” this is the effect which enables the ear to establish spatial volume and size of a percepted room.”
The original Quantec QRS - picture courtesy of Reverb.
The QRS was able to create seven room sizes from 1 to 1 million cubic metres in a very realistic way, with reverberation times ranging from 0.1 and 100 seconds. It was a perfect fit for enhancing studio recordings which were often ‘dry’ and lacking ‘room’ sound. Although it only had eight parameters and lacked more complex controls like its competitors, (Like the Lexicon units of the time), it had a peculiar sonic signature that immediately captivated music professionals. This is mainly because of the way it processed the sound, relying on mathematical models that creates the resonance of a sound on a given space instead of trying to simulate what’s happening when a sound hits such space. Its unique resonator-based approach and independent first-reflection level adjustment lead to a studio reverb that is creating an effect that sounds more natural and less metallic, which was a frequent criticism of digital reverbs of the era.
Beside the main reverb, the QRS featured an extra effect: Enhance. The Enhance effect can be considered as a different flavour of reverb, but one where the sound is distributed differently than the regular program, featuring a “reflection cluster” that consists of reflections with equal strength that is followed by a decreasing set of reflections.
Illustration of the enhance and reverb programs taken from the Quantec-QRS Manual.
However, despite its success and cult-status it acquired, it’s not all rainbows and unicorns, the Quantec had some drawbacks: the limited availability and hefty price made it quite an exclusive unit, and only the upper echelon studios, or people that could afford to hire one, were able to enjoy its fabulous sound. Fast-forward in time, right now there are only a few of those units left, and finding one in mint condition is a hard and often fruitless endeavour, so it’s a classic case where having a faithful emulation in plug-in form is something most of us would welcome.
If there is one company capable of delivering such a plug-in, that company is Relab. After successfully bringing the legendary Lexicon 480L reverb and Maselec MEA-2 equalizer for our DAWs, they have more than proved themselves to be one of the leading companies when it comes to making fully accurate emulations of hardware gear. Relab has deep expertise when it comes to reverbs, and besides the 480L they have also created Sonsig Rev-A, an innovative algorithmic reverb plug-in that delivers superb quality without overwhelming the user with overly complicated controls, and the company is also working on an emulation for the iconic TC Electronic VSS reverb, which is currently in its last stages of development and on public beta, so there’s no better candidate for this job of bringing the Quantec QRS to the 21st century.
The QuantX Plug-In
It starts with a picture-perfect interface but underneath there is an extensive analysis and coding work to recreate the original unit in all its glory - including its imperfections and even its obscure quirks. According to Relab, “heat-induced behavior changes, including clock fluctuations due to temperature variations, had to be taken into account. With a ±3% stability factor, these fluctuations significantly impacted reverb coefficients, which was vital to recreating the true feel of the original.”
The trademark Relab dual-engine architecture also makes a comeback here, with one engine solely dedicated to the main reverb and a second one solely for the Enhance effect. This ensures that both effects have uncompromised sound quality that is truly faithful to the original hardware, and it allows users to control each one separately for seamless control of each stage.
The QuantX plug-in also takes the QRS to new heights with enhanced bandwidth and Relab’s proprietary Advanced Chorus Ensemble (ACE). As those familiar with vintage reverbs might suspect, the original unit from the 1980s had to compromise on its operating bandwidth due to the converters of the time, which were limited to sampling rates that are lower than what we enjoy today - and this is part of its charm. On top of that, the Quantec also featured an analog low-pass filter rolloff around 8 kHz besides the 10 kHz bandwitdh (20 kHz sample rate) of the digital algorithm, which softens the top end for a more smooth sound. This is present on the plug-in, but it also opens up the possibilities by offering extended filtering options from 4 kHz to 16 kHz, and according to Relab these roll-off points were carefully chosen in order to “follow a specific geometric sequence (Renard Series), which, we believe, is what the original designers would have used had they ever chosen to enhance the original hardware”. Furthermore, these are not the usual low-pass filter, but a recreation of the converter’s sample rate and analog filters from the hardware, with all its resonance peculiarities.
The Advanced Chorus Ensemble takes modulation to a new level, with eight voices running in series on the dual-engine for a total of sixteen voices that were hand-tuned with a custom tool (pictured above). Before anyone asks, this tool is not available to users and was used only for development purposes so Relab could really zoom in and put together a modulation layer that is deeply intertwined with the reverb - all the user has to do is dial the modulation knob and blend in the desired amount for a rich-sounding effect that doesn’t feel dislocated from the reverb. Values below 10% can provide subtle movement and chorusing, whilst higher values can be used to increase the richness and density of the reverb.
The interface has also been refined and optimised for modern computer screens, offering resizing options from 75 to 200%. The original unit relied on buttons for most operations, and these have been replaced with knobs for a more fluid workflow - we can all agree that clicking on “+/-” and numeric buttons with a mouse simply doesn’t work well. The central encoder for reverb time, volume sliders and metering were all preserved as they’re certainly in the “if it ain’t broke don’t fix it” category: taking lessons from the past and building upon them is definitely the spirit here, and after the huge success of the LX480 plug-in, it’s safe to say that Relab has brilliantly future-proofed yet another classic reverb.
The Relab QuantX plug-in is available right now as AAX, Audio Unit and VST for Mac and Windows. For a limited time, you can get the QuantX plug-in for $149 (regularly $199) or pay over time with 3 payments of $49.99/month. A 7-day fully functional trial is also available.
For more information, demo or to buy, please visit: relabdevelopment.com
