dynamicwavestudio 
Uncover the science behind the world’s most trusted audio interface.
Within the crowded discipline of audio interfaces, Common Audio’s Apollo has risen above all the remaining. Used on lots of of Grammy-winning albums since its introduction in 2012 — from Kendrick Lamar and the Black Keys to Ariane Grande, Inexperienced Day, and Tyler, the Creator — Apollo interfaces are commonplace in professional studios world wide.
However what precisely makes them sound higher than the competitors?
On this article, we’ll discover the extent of element we have put into the Apollo line of desktop and rackmount interfaces, particularly its elite-class AD/DA conversion, and speak to the folks behind its impeccable sound high quality.
Apollo: A Easy Design Philosophy
Dave Rossum is a legendary synth pioneer who led the design of Apollo X Gen 2 converters.
Though the start of Apollo was a large group effort at Common Audio, one in every of its most important drivers is UA Technical Fellow, Dave Rossum.
A pioneer of the synthesizer revolution, inventor of the polyphonic keyboard, and co-founder of E-mu Techniques, Rossum modified the course of recent music with the E-mu SP-1200 sampling drum machine — a groundbreaking gadget on the middle of lots of of basic pop and hip-hop information over the previous 4 many years.
“With Apollo it isn’t nearly specs, we’re searching for sound.”
— Dave Rossum, UA Technical Fellow
By way of all of his legendary designs, Rossum makes use of a single core precept as his guiding mild, and Apollo interfaces had been actually no totally different.
“I attempt for a easy design,” says Rossum. “And for me which means getting a circuit topology that works cleanly, somewhat than tweaking issues to zero in on optimum specs. Plus, we’re not chasing specs, we’re searching for sound. Positive, specs are important, however actual listening by golden ears issues too. There are nuances too delicate to measure scientifically, however to an skilled ear, they are often distinctly audible.
“The listening checks range. Some are easy, casual consensus. Others are extra subtle and scientifically designed for true ‘double blind’ testing.
“We improve this by additionally testing — by together with a number of similar copies within the desire checklist — whether or not the listeners can really distinguish when sounds are similar. This enables us to essentially know what’s clearly audible, and what’s most well-liked, versus easy take a look at situation artifacts.”
Apollo: Class-Main Audio Conversion
On the coronary heart of any audio interface’s sound is its AD/DA conversion. AD/DA stands for analog-to-digital (AD) and digital-to-analog (DA) conversion. These processes are vital to recording and enjoying again sound within the digital world. Excessive-quality AD/DA conversion is crucial for precisely capturing and delivering each nuance of sound, just like how a high-resolution digicam captures each visible element.
For eight many years, Common Audio’s impeccable craftsmanship has made it the trade chief and most well-liked alternative for Grammy-winning artists in each style.
“With Apollo, transparency is the purpose, however there’s all the time going to be some perceived, subjective alteration to the sound,” says Rossum.
“We selected the ADC (audio-to-digital converter) for Apollo notably as a result of we just like the sound of it,” he continues. “Whereas the operate and specs of it appear akin to those in different interfaces, every trendy converter has its distinctive quirks associated to the “chaotic” math algorithms. As for the DAC (digital-to-analog converter), they often have higher specs than ADCs, so with cautious element choice it’s simpler to get a clear design.”
Over time, Apollo interfaces have had numerous enhancements, however the newest Apollo X Gen 2 interfaces provide the perfect AD/DA conversion but, with unprecedented low noise and distortion (as much as 0.000037% THD+N).
The sound of Apollo interfaces is the results of over 20 years of audio conversion design relationship again to our legendary 2192 Twin AD/DA Converter.
“See, trendy audio converters all use a know-how referred to as ‘delta-sigma’ modulation,” continues Rossum. “This avoids the requirement for matched analog parts that had been wanted within the old-style ‘R-2R’ converters of the Eighties.
“They use some subtle DSP and really excessive pattern charges — 6MHz and even a lot larger — to maneuver all of the artifacts of sampling — the stuff sometimes referred to as quantization noise or distortion — out of the audio band.
“Sadly, these mathematical algorithms can have objectionable resonant modes, so they’re intentionally designed to be considerably unstable or chaotic to interrupt up these modes, which may coloration the sound. Each interface producer has their very own ‘secret’ implementations, so every sounds a little bit totally different, despite the fact that they’re all designed to check effectively utilizing the usual Dynamic Vary and THD+N checks.
“Fortunately, we found quite a few circuit enhancements that diminished distortion and noise in Apollo X Gen 2,” Rossum continues. “There have been quite a lot of small tweaks based mostly on classes discovered, all of that are a part of our dedication to constantly bettering our merchandise.”
Apollo X Gen 2 interfaces provide class-leading jitter efficiency. In an audio interface, jitter impacts the conversion of digital audio indicators to analog (or vice versa) and introduces undesirable artifacts like noise, delicate distortions, or a lack of readability. It’s particularly essential in high-quality recording and playback.
With Apollo X Gen 1 we launched the idea of Twin-Crystal clocking for Apollo rackmount interfaces. Twin-Crystal clocking is a premium circuit topology that depends upon optimized crystal-oscillators because the clock supply to take care of consistency and exact timing.
Apollo X rackmount interfaces use one crystal oscillator for 44.1 kHz associated pattern charges, and one other for 48 kHz and its associated multiples (96 or 192 kHz for instance). By doing this jitter is minimized throughout the audio band with out compromise, making certain Apollo X rackmounts sound constant, it doesn’t matter what pattern price your session is at.
“Sustaining exact timing for digital audio indicators, each inside and exterior, is essential.” says Rossum. “It actually comes all the way down to the nice particulars of the parts, “but in addition the format of the PC board and exact, in depth early-stage QA.”
“Apollo X Gen 2 headphone amps have 5 instances much less THD+N, dropping a staggering 14 dB.”
— Dave Rossum, UA Technical Fellow
Apollo X Gen 2 desktop interfaces provide the identical class-leading sound because the rackmount variations.
One other massive enchancment of Apollo Gen 2 interfaces is the headphone amp — one thing very noticeable the minute you plug in a pair of cans, with a jaw-dropping 0.0013% to 0.00025% distinction in THD+N in comparison with earlier Apollos.
“For earlier variations of Apollo, we used an off-the-shelf IC (built-in circuit),” explains Rossum. “However with Apollo Gen 2 we felt we may do higher by ‘rolling our personal’ out of discrete parts. Delightfully, the outcome was an enchancment in specs, however extra importantly, sound.”
“With Apollo interfaces, the satan is within the particulars,” says Rossum. “It is not one thing rivals can simply copy. There’s far more to it than simply the schematic.”
— Darrin Fox
