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How the Sound That Defined 80s Music Still Lives on Today

The AMS RMX16 was a reverb effects unit invented in 1981, and chances are it's been used on some of your favourite songs.
November 27, 2015, 10:00am
Image: Mark Crabtree

If you've listened to pretty much any popular song from the 1980s lately, you're already well aware of what a device called the Advanced Music Systems RMX16 can do. It practically defined the drum sound of the era, starting with the booming, ethereal drums of Phil Collins' "In the Air Tonight."

The sound has been ubiquitous in pop music ever since, and for that, you can thank an effect called reverb. It's the process of altering a sound to give it the illusion of coming from a larger, more reverberating or echoing space. Traditionally, a reverb effect was accomplished by playing music in actual spaces such as halls or caves, and later, by sending audio through large metal plates or springs.


The Advanced Music Systems RMX16, however, was one of the first to bring this capability to the masses using digital technology that accurately and complexly recreated a plethora of analog reverb processes in a single unit.

Built by AMS audio engineer Mark Crabtree in 1981, the RMX16 was lightyears ahead of its time in terms of flexibility and customization. Unlike traditional reverb, digital reverb used used code and feedback delay circuits to emulate physical spaces, simulating a large series of echoes that decayed over time.

While there were units before the AMS RMX16 that emulated reverb digitally, the RMX16 was the first to do so with the addition of a microprocessor. Amongst other things, this meant that the unit could store and recall up to 99 user presets, a relatively new feat in the 1980s. It provided studios with access to a plethora of different reverb sounds and configurations at the touch of a button, all painstakingly designed. Peter Gabriel was Crabtree's first customer, and these days, you would be hard pressed to find a major recording studio without at least one RMX16 amongst their gear.

Peter Gabriel's "Sledgehammer" used an RMX16,

amongst other things


A wealth of artists, including U2, Rihanna, and Radiohead have all used the RMX16 on celebrated records. There's even a digital version, a plugin, that came out last Fall, ensuring its legacy lives on in software for decades more to come.


"Given that a digital product often has a normal shelf life of six months before it is superseded and the RMX16 is still going strong and in demand 34 years later, it must have achieved the status of a true distinct standard, and a unique sound that's much sought after," Crabtree told me in an interview.

At the age of 12, Crabtree began learning the guitar, but soon started to immerse himself in the then-nascent musical electronics industry. "I inherited a large collection of old radar and radio electronics from my mother's cousin. I then built an amplifier, amongst other things, out of the bits, followed by experiments with tremolo," he recalled.

Crabtree went on to receive an engineering degree from Cambridge and a Masters from Manchester, and while working on microprocessors for an aerospace company, inspiration struck. "I found a component I thought I could make a solid state tape echo from, but it was too noisy," said Crabtree. "So instead I designed a tape phasing box." (Tape phasing is when two pieces of sound recorded to tape are played at once, and fall out of sync with each other, creating a warbling, swirling, psychedelic effect.)

He left his cushy job to take a chance on designing audio hardware, founding Advanced Music Systems in 1976. The tape phasing box, called the DM-20, was his first product. It meant that producers could now employ a tape phase effect without the cumbersome process of dealing with reels of analog tape.

Peter Gabriel with his rack of recording equipment, including an RMX16. Image: Mark Crabtree

"After that a studio asked for a digital delay line and funded its parts cost. From that the DMX 15-80 DDL was born," said Crabtree. The DDL was later outfitted with upgrades such as pitch changing capabilities, and eventually loop triggering—the addition of which paved the way for modern digital sampling as we know it. It was the success of the DDL that led to the RMX16.

"The RMX16 came out of feedback from our customers," said Crabtree. "They loved the delay line, then loved the addition of the pitch changer module, and then wanted a reverberation card to go in the DDL. The power needed to create good reverb wasn't available in the DDL so I set out to design a stand-alone system."


One thing that set the RMX16 apart from its competitors was Crabtree's attention to quality and precision. During development, he would work on a setting, test it out, and further calibrate it by hand to achieve the sound he wanted—a wildly labor-intensive process. "I had spent a year tuning it by ear," Crabtree said.

Eventually, as time progressed, the switchover to digital studios and the expense and time of keeping the old digital units working created the need for a plugin version to run on modern digital audio workstations. Crabtree was first asked by the audio effects software company Universal Audio to make a plugin version over several years ago, but "was not prepared to have a pale imitation of the sound," he said.

"I was very busy running the company and I knew I would have to spend many, many months working out how I had actually designed it," Crabtree recalled. According to Crabtree, the design of the AMS RMX16 was so idiosyncratic and precise that he initially believe it impossible to simply recreate it digitally through emulation. "The design was basically not able to be reverse engineered—or someone would have done it!" he explained.

However, the demand from Universal Audio was great, and eventually Crabtree put himself to work redesigning the unit from the ground up—this time, digitally—much like he had done with the original RMX16.

The development went through several phases, with Crabtree experimenting with several different ways to deconstruct and reconstruct the unit. The main problem he kept running into was that the plugin version was simply too huge when reconstructed and laid out linearly, so Crabtree would have to think outside the box. Eventually, he succeeded in doing what he once deemed unthinkable.


"I came up with a radical scheme where the plug-in could rewrite parts of itself whilst running, which allowed me to compress the algorithm down to a manageable size."

Crabtree then sent a beta version of the plugin to his son Tim, a Canadian musician who plays under the moniker Paper Beat Scissors. Tim was born when Crabtree was writing the code for the original RMX16. The digital version of the RMX16 ended up being used all over his recent album, "Go On."

When pressed as to how the plugin version stacks up against its beefy physical predecessor, Crabtree had no hesitation.

"Over a period of nearly two years, we exhaustively ironed out every difference between the hardware unit and the plug-in. They're the same," he said.

Now in software, too, the RMX16 will continue to live on.