Calliope
By Robbie Rhodes
For several years I operated and maintained 43-key and 52-key air calliopes, made by Tangley and National. The ubiquitous Rootes blower had poor oil seals, and so SAE-30 lube oil was sucked into the air supply and combined with ambient dust. I always had with me a short piece of brass shim stock to clean the wind-wheet aperture, which would be fouled with oil and dirt after and hour or so of playing.
The Tangley and National whistles were voiced for operation above 2.5 psi, I believe, and sounded best at higher pressures. When I operated the calliope at Disneyland, in the mid 60s, the blower was fitted with a puny battery-powered electric motor. I thought it sounded weak and wheezy. The battery charge lasted only about 1/2-hour, enough for one parade through the park.
I loved the sound the best when the blower was powered by a 5 or 6 horsepower gasoline engine -- then I could crank down the blow-off valve and run about 3.5 psi (pounds per square inch) pressure. This pressure was the maximum which could be applied without overblowing whistles into harmonics. I wore aircraft-engine-rated ear protectors, too, and on a quiet afternoon in the suburbs it could easily be heard over a quarter-mile away!
High pressure on the valves also helped playing while bouncing around in a parade, because of the key-force hysterisis. With high pressure the keys felt like a harpsichord, but at low pressure they felt like an old reed organ, and it was difficult to control. I liked the high pressure best.
The calliope whistle (pipe) is a simple cylindrical stopped flute constructed entirely of brass. The wind-sheet is continuous about the circumference of the resonator, and the mouth of the whistle has a long cut-up; this large wind-sheet area is what produces the great sound intensity. By careful adjustment of the cut-up distance, the wind-sheet aperture and wind-sheet angle, the whistle will oscillate initially at only the third harmonic, and then a moment later the fundamental tone will slowly get going. That's what makes the nice "bark". Sometimes the aperture plate in the larger whistles is allowed to move slightly under pressure, thus altering the initial wind-sheet angle. The steady-state oscillation also has a very high 3rd-harmonic content. I always suspected that the "white noise" of the air was somehow amplitude-modulated by the harmonic structure, too, but I couldn't prove this in experiments with a Yamaha DX7 synth.
The instruments I worked with were of quite simple construction: a threaded nipple on the base of the brass whistle passed through a hole in the sheet iron horizontal deck, and was secured underneath with a big nut. A neoprene hose, about 1/2-inch inside diameter, connected the whistle to its valve in the valve chest under the keybed.
But the long, large hose required a bit of time to charge up to operating pressure after pushing the key, and I felt that this reduced the "bark", or "chiff", sound. Therefore I always wanted to make a "tracker calliope", in which the valves would be directly under the whistles.
One of the Tangley calliopes I operated had a player mechanism for A-rolls. Only one or two 10-tune rolls sounded good, though, because piano arrangements aren't well suited for organs. The best roll as I recollect was entitled, "Circus Echoes". It was tricky, adjusting the suction regulator for the player, because when the music ended between songs and the pipes weren't operating there wasn't enough airflow for the wind motor!
Digest 960208 has a note about a calliope for sale. This contemporary replica Tangley has a separate vacuum pump for the player, and an electric motor for the roll drive. Other notes concerning calliopes are in the Digests for 950821, 951030 and 951115.
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(Message sent Sun 21 Apr 1996, 18:55:50 GMT, from time zone GMT-0700.) |
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