'A' Range - INTRODUCTION
I had built various prototypes at home before I found Chelsea. Now we had to get down to the serious construction. Again, many decisions had already been taken. Jill and I had gone to Northampton to see Elcom, and agreed to use their half moon faders. (They gave us each an engraved penknife which we still have.) The mixer was to be for four track. Channel selection would use a bus-bar technique I’d read about in an American magazine. So, we needed four main bus’s, one for echo and one for fold back. This technique was called constant current mixing (now called virtual earth mixing) - as opposed to constant voltage mixing which I’d previously used.
I had made the prototype printed circuit boards at home. I used to buy the components from a small electronics wholesaler in Park Royal. I have never forgotten a piece of advice from the man behind the counter. “People soon forget the price they’ve paid - its the quality they remember”. I was never very good with trays of chemicals, so we responded to an advert in Wireless World or Practical Radio - I can’t remember which - from a company near Manchester. Each batch took forever to arrive. By the time I’d driven from Ealing to Chelsea in the morning’s rush hour, I was ready to explode. I’d wait for the post and then ring the printed circuit man. I got the same kind of stories that were later to become familiar when we opened and were chasing cheques! The final straw was when he again apologised. This time the delay was because his horse had died! Eventually, they did all arrive; so we faced the next task. The board’s output transformers. Again, shortage of money prevented us from having these wound for us. We bought the empty bobbins and laminations, it being John’s job to wind them. Our coil winder was the electric drill clamped in the vice. He operated the drill, while I held the reel of wire on a pencil. Of course, variable speed controls for electric drills had yet to be invented. One mistake and the thin wire snapped. (This meant finding the end, which had buried itself into the mass of wire on the bobbin, and un-winding the mess by hand.) The next stage was to fit the laminations. We became quite speedy at this, but it was always difficult to squeeze in the last one.
John produced drawings of the front panels, and we got 10 gauge aluminium panels cut to size. It was my view that we could not afford to have these painted and engraved. Luckily, John convinced me that this would look awful. But, we did drill them ourselves. By now, we had a vertical bench stand for the drill. John taught me how to mark out the panels, drill pilot holes, and then drill from both sides to reduce burrs. He became so fed up with my breaking the small pilot drills, that he took over the drilling. Small batches of five similar panels were clamped together in a Mole wrench, and then drilled. When painted in a metallic grey, and engraved in black, they looked exceedingly professional. I chose Bulgin knobs. Large, ugly ones. (After this, John became very pedantic about the shape and appearance of knobs. Later, he was to be equally fastidious about screws!)
Slowly the console took shape. Each microphone amplifier had a preset gain control. All the ex-army equipment I had bought in Lisle Street while at school used wire wound potentiometers. It was a mistake to use them here. Every time you turned the knob, great bangs came out of the speakers.
I had made the prototype printed circuit boards at home. I used to buy the components from a small electronics wholesaler in Park Royal. I have never forgotten a piece of advice from the man behind the counter. “People soon forget the price they’ve paid - its the quality they remember”. I was never very good with trays of chemicals, so we responded to an advert in Wireless World or Practical Radio - I can’t remember which - from a company near Manchester. Each batch took forever to arrive. By the time I’d driven from Ealing to Chelsea in the morning’s rush hour, I was ready to explode. I’d wait for the post and then ring the printed circuit man. I got the same kind of stories that were later to become familiar when we opened and were chasing cheques! The final straw was when he again apologised. This time the delay was because his horse had died! Eventually, they did all arrive; so we faced the next task. The board’s output transformers. Again, shortage of money prevented us from having these wound for us. We bought the empty bobbins and laminations, it being John’s job to wind them. Our coil winder was the electric drill clamped in the vice. He operated the drill, while I held the reel of wire on a pencil. Of course, variable speed controls for electric drills had yet to be invented. One mistake and the thin wire snapped. (This meant finding the end, which had buried itself into the mass of wire on the bobbin, and un-winding the mess by hand.) The next stage was to fit the laminations. We became quite speedy at this, but it was always difficult to squeeze in the last one.
John produced drawings of the front panels, and we got 10 gauge aluminium panels cut to size. It was my view that we could not afford to have these painted and engraved. Luckily, John convinced me that this would look awful. But, we did drill them ourselves. By now, we had a vertical bench stand for the drill. John taught me how to mark out the panels, drill pilot holes, and then drill from both sides to reduce burrs. He became so fed up with my breaking the small pilot drills, that he took over the drilling. Small batches of five similar panels were clamped together in a Mole wrench, and then drilled. When painted in a metallic grey, and engraved in black, they looked exceedingly professional. I chose Bulgin knobs. Large, ugly ones. (After this, John became very pedantic about the shape and appearance of knobs. Later, he was to be equally fastidious about screws!)
Slowly the console took shape. Each microphone amplifier had a preset gain control. All the ex-army equipment I had bought in Lisle Street while at school used wire wound potentiometers. It was a mistake to use them here. Every time you turned the knob, great bangs came out of the speakers.
Plans for the mixer had been forming in my mind since I left Levy’s.
The first mic amp on a paxolin board. (Fibre glass was too expensive then!
By 1968 we had a proper factory!
Not home made!
.. and wiremen too!
The prototype EQ
The "Schematic"!
