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GENIUS! #9: Ivor Drawmer and the frequency-conscious gate

David Davies 13 February 2015
Ivor Drawmer

There’s a story online that suggests Ivor Drawmer’s world-beating gate processor was born of frustration after a session in the studio. It goes along these lines. A sound engineer couldn’t get the result he wanted when recording a drum kit because the cymbal crash kept opening the mic on the toms. Young Drawmer, a keyboard player on the session, realised he could fix the problem, and returned the next day with a hastily assembled circuit board with a couple of connector leads attached. When the engineer wired in the device, he was stunned to find the toms opened the gate, but the cymbals did not. Bang, the frequency-conscious gate had arrived….

Is this how it happened, Ivor? Did you really solve the issue ‘overnight’?
“I’m afraid the story is not quite correct. It’s true that engineers wasted an inordinate amount of time trying to gate the drums. I saw a lot of that: trying different placement of mics and fiddling with the gate threshold to get a reliable take. So I discussed the problem with engineers and wondered how it would be if the gate didn’t hear the cymbals and vice versa.

“I concluded that separate low and hi pass filters working in conjunction with the gate would be the most versatile solution to this and I started work on a design. But triggering wasn’t the only problem. Most gates on the market at the time had a slow attack time and only attenuated to 40dB, leaving unwanted noise in the background. The result was better than nothing, but, well, let’s just say there was room for improvement….

“I had made a single channel prototype which we still have – and it works! The first demo I did of the gate was at Fairview Studios near Hull. I’d known the owner, Keith Herd for a few years: a lovely guy, and technical, having built his own desk in the ‘70s. We rigged up the gate and he played a track with the gate shut. Nothing! So he wound up the gain and the gate opened, nearly taking out his speakers!”

“Impressing Keith wasn’t easy. He’s heard it all and built plenty of gear himself. So when he went ‘WOW!’, I knew I was on to something. That was a good feeling – so went into production with the DS201 gate.

“That was in 1982. You can hear the difference in drum sounds between pre- and post-1983/4 as studios bought them.”

Were you a natural with electronics and circuit design, or was it something you came to through long periods of learning and experimenting?
“I was interested in electronics from the age of 11 and it has remained my hobby ever since. I worked as a test engineer at Tektronix and did a couple of short courses there. Then I decided to start a band. I wanted a Hammond organ but couldn’t afford one, so I set about building an organ and learned a lot during that process. The rest I learned along the way, repairing amplifiers in the van on the road from one gig to another. Making little sound effect boxes in tobacco tins!”

What impact did your invention have on your business/company?
“It changed everything. Suddenly the business had to expand and get serious. We turned pro. From a guy in a basement to a small factory in a couple of months.”

What was your next move as a designer/inventor?
“Compressors. The first two were the DL221 and DL231, now discontinued, followed by the 1960, which is still selling after 30 years.”

What are your thoughts on having contributed something so important to the recording industry?
“There are a few pro-audio products over the years which could be described as landmark products. If the DS201 is regarded as one of those, I’m proud of that. Fantastic.”

www.drawmer.com

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