By PSW Staff • February 2, 2011 Bruce Jackson GRAND EXPERIMENTS We also experimented with new crossover designs, equalizers and methods to get the PA dynamics under control. Our first attempt to prevent the amplifiers from blowing up was to put dbx 160 RMS (Root Mean Squared) limiters on each output from the crossover, right before the amplifiers. The amplifiers used to blow up all by themselves let alone from being overdriven. The RMS limiters used dbx proprietary RMS analog modules to control the dynamic range. RMS is a method to measure the true heating power of an alternating voltage. Loudspeakers can tolerate very high peak power, but it’s the RMS power heating the voice coil that will do them in at some point. So it makes a lot of sense not to use the transient peaks or audio average to limit the power output. RMS limiting has the added benefit of sounding smoother and more natural. The short transients get through, and the extended high power is reduced. The Clair console that folded out of its case and included plasma bargraph meters. (click to enlarge) In the early ‘70s, Ron Borthwick and I developed a very unusual mixing console for live sound, and it went on to become Clair Bros’ mainstay mixing console into the ‘80s. It was unique on a number of fronts. The control surface folded right out of the case – no heavy lifting up on to a table. It was the first console to have plasma bargraph meters, which also displayed simultaneous RMS and peak levels. And the meters were conveniently located beside the faders, right where you tend to look. In addition, it was the first live mixing console to have parametric EQ. I had researched the circuits in a prototype console I built in Australia. Before that, the only EQ options were external graphic equalizers and various stepped frequency filters. To be able to continuously tune the frequency and change the shape was a fantastic new experience. Roy Clair patching one of the first live mixing consoles in 1971. It used magnetic inductors shaped like mini doughnuts, borrowed from the graphic equalizers on the left, to create the switchable EQ. (click to enlarge) I like to think that when I hear a problem frequency I go right to it on the equalizer. In reality, I’ll probably have to grab a couple of different sliders on a graphic EQ to find just the right one. The continuously variable frequency control of a parametric EQ lets you sneak up on exactly the right area of interest. The prototype console I built in Australia actually used linear faders to tune the frequency. I always liked that idea because you get a better graphical representation of the frequency. The position of the sliding knob shows the frequency setting, contrasted to having to look down on a rotary knob to find the frequency. My friend Morris used my circuit and linear potentiometer idea to build the first parametric EQ for the hi-fi industry, under his SAE product line. Prototype of the first parametric EQ for live audio. Note linear faders for frequency selection and boost/cut to allow the operator to see the EQ condition in a quick glance. (click to enlarge) Today it’s nearly impossible to find a professional mixing console without parametric EQ, which enables you to change the bandwidth coverage with a simple twist of a knob. The shape of the selected range of frequencies is a function of the resistors and capacitors. The same basic bell curve shape is shared by all EQs, both digital and analog, and is very difficult to vary. For my taste, the filter shape we’ve all been using for years skirts into neighboring frequencies that I often don’t want to affect. Bruce and “The Boss” walk Madison Square Garden in 1978. Springsteen liked to walk to every area of the venue while the E Street Band played. Jackson dreamed of a remote control. (click to enlarge) I went back to Australia for a couple of years and founded a joint venture called Clair Bros Australia P/L, which competed with my old company, JANDS. It was a great experience as a mixer because we had to take every tour that came along, but it could become a bit boring because other than the occasional tour in Japan, Hong Kong or New Zealand, we covered the same four or five cities in Australia. So I moved back to the U.S. The successful joint venture with Clair set up the relationship that would follow years later for the development of the new processor. I left Clair Bros in 1978 and worked for Bruce Springsteen over the next 10 years, and in between tours I started a couple of businesses with the aim of relying less on a life on the road. The first business was promoting and setting up distribution for the first music sampler, from Fairlight. Some friends in Australia created it in the house next door to where JANDS was founded, believe it or not. Read the rest of this post 1 2 3 4 5 Comments Have something to say about this PSW content? Leave a comment! Cancel reply Scroll past the ”Post Comment” button below to view any existing comments. Your email address will not be published. Required fields are marked *Comment Name * Email * Website This site uses Akismet to reduce spam. Learn how your comment data is processed. Peter Maurer says I spent many hours in that Santa Monica garage with Bruce showing me all what he describes in the above story; and then so many more amazing projects he developed. Bruce, we will miss you and never forget you; R.I.P. Anisa says I love you uncle Bruce. I will miss you so much!!!! I still can’t believe I was just talking to you 2weeks ago. You always talked about how I’m growing up so fast and asked me about school. You were the only man that I could call the wizard of electronics.It came as a total shock to me when I found out. I’ll be praying for you and of course my aunt and cousins. I feel so awful. Thanks for taking me ice skating for the first time you know how much I wanted to go. I appreciate everything you ever did for me. I can’t stop thinking about you and I love you. Sooooooo much <3 ); anisa/ aj David Gibbons says I had the pleasure of knowing Bruce for about the past 10 years. In my experience, he was everything people have said about him-warm, funny, egoless, brilliant, gentlemanly-and if you worked in pro audio, inspirational. I always felt privileged to know him, but he was so easy-going, you just felt glad to be with him. He and I talked about digital console design from time to time while I was working through the design cycle for the Digidesign VENUE consoles. He was working on the Lake Contour at the same time, and I could tell he was itching to do another mixing console design. It’s really too bad for the world of live mixing that he didn’t get a chance to do so. His legacy will guide us into the future; a better one for his having been here. Farewell Bruce. Tagged with: Apogee Bruce Jackson Concerts Heritage and History Lake · all topics Subscribe to Live Sound International Subscribe to Live Sound International magazine. Stay up-to-date, get the latest pro audio news, products and resources each month with Live Sound. Subscribe Today!