Auxetophones and Talking Flames

lapinbleu writes:
I heard an entertaining piece on Radio Four yesterday about the Auxetophone, a pneumatic amplifier from a hundred years ago. This device was fitted to a standard phonograph, and had compressed air (5 p.s.i ) from a reservoir passing through a "comb valve", which appears to have had a fixed and a mobile metal plate with fine slots, one of which, when moved by the vibration of the pick-up, modulated the air supply. The one they demonstrated (on a beach) sounded dreadful, but it was *loud*, 132dBA at the mouth of the gonzo horn. Have a look on -
Here they also write of it being fitted to a 'cello. Charles "Turbine" Parsons had a hand in this, apparently. It was also known as the "Bellowphone"...
This reminds me of a device I saw when younger. At 16, answering a newspaper advert, I applied a job in a car body-shop. I could tell straight away that it would be a bit special - turning up for an interview early in the morning, along with a dozen other hopefuls, the boss has set out a number of squares of Masonite, ½" paintbrushes, and wall-paint in plastic cups.
- "I've not got time to talk to you all - you'd only lie through your teeth anyway. Paint half the board with the paint..." and Blam!, he's in his office; coffee ...
We all looked at each other - this was not what we spotty hopefuls had imagined that a job interview would be like at all. Not having any measuring tools, and thinking that finding the middle by balancing the board on my fingers would not be accurate enough, I held it up against the door-frame and struck a line from one corner to the other. Well, that's half... washed the brush... Got the job.
Later, vetting potential apprentices, the first thing to do was to pretend to be busy, ask them to make the tea. This speaks volumes, far more than bullsh*t C.V's and uncomfortable collars... A man who jumps on deck is not a sailor, and unlikely to become one in a hurry when it gets rough.
So, arriving one Monday, there is a strange apparatus on a tripod. A hefty steel plate with two pipe nipples is glued and bolted to the front of a 12" chassis loudspeaker. Acetylene from the cylinder arrives at the bottom, and flows out again through a tall stand-pipe, bashed flat at the end. A hefty, luminous, fan-shaped flame is lit at the top. Wire wool in the pipe prevents blow-back.
Plugging the 'speaker into his guitar amp, the gas flow, and thus the flame, are modulated by the moving cone, making a Thermic Amplifier. Shades of the Burning Bush! The sound was astounding, and seriously threshold-of-pain loud. Not very linear, so none too convincing for opera. But with an electric guitar...
I don't mind a lazy boss if he makes impressive gadgets, and plays good blues while you're working.