Leslie SuperTyfon: the Sole Chime Horn Provider - Part 2

It was in 1958 that the use of bronze in power chamber was substituted by aluminum. The lesser production expenditure and the weight were the primary reason why the bronze design was replaced by aluminum. These grounds were sufficient to disregard the fact that aluminum deteriorate fast. About the year 1968, the style was enhanced with a metal on the outer circumference outside the bolt circle. The enhancement improved the quality of the product. It had also solved the detaching tabs in older chambers especially when hit in a wrong direction. However, the new configuration preserved the interchangeable features of the diaphragm as well as the back cap with the diffuser plate. The style achieved were totally a round power chamber, thus termed as the "round-back" or "dome-back" chambers. The term is regardless of the fact that tab-back chambers appeared to have a dome-shaped back cap.

As time passed by, the incapacity of the SuperTyfon horns were eventually discovered. The presence of grease, dirt and other contaminants of all sorts in the atmosphere is an aggravation of the effects of deterioration. Naturally, railroads have dusty air surroundings and there's no way to completely eradicate the present contaminants. For this reason, the Leslie Company sought for the construction of a newly improved chamber, that was called RS power chamber and the "improved" power chamber. Apparently, the design looked like the dome-back power chamber only with the slight difference that it is flat with a big spike that overhung on the back side of the back cap. This spike is included for maintenance purposes and it supports the diaphragm in bringing back force. The diaphragm on the new style is completely different from the older chambers. The new diaphragm consists only of one stainless disk cushioned in silicone ring resting behind the back cap. The silicone ring acts as the protection of the outer parts of the diaphragm against prolonged use of the horn. RS power chambers is also known in layman's term as "spike-back" power chambers due to the presence of spikes. The tendency of failure is lesser in spike-back power chambers than those dome-back and tab-back power chambers.

The air flow cannot be limited on the old-styled bronze power chambers as it enters the opening ports to the power chamber. This is associated with its "full-orifice" configuration. Not until the SuperTyfon series horns became available in which a technique was discovered to limit the amount of air in the horn. A hollowed aluminum dowel was attached to the opening on the power chamber. The air entering the chamber is limited by the sizes of holes drilled on the opening dowel. The holes are drilled in order to lead the flow of air to the opening of the chamber. Hence, horns with variable orifice are made without the task of re-configuring the power chambers. Variable-orifice horns deteriorate in longer time while staying balanced in distant spaces. In view of the new breakthrough, Leslie relocated the dowel to the bell. The said modification also eased the task of arranging the orifice size with the appropriate bell. All of the mentioned highlights happened within the first couple of years in the history of SuperTyfons. Various orifices existed commercially since then.

Equally, the design of the bell underwent gradual modification through the years. Unlike the AirChime bells that are numbered in 1, 2, 3, etc, the Leslie bells are identified according to the frequency of the resulting sound measured in Hertz. A 237 bell gives off a 237-Hertz sound or B below middle C. Within the two years of production, the three-digit bells were utilized and placed on a rectangular plate elevated at the base of the left panel of the bell. In 1952, the bell numbers were made to two digits after the first models (S-3J, S-5D, S-3E, and S-5A) were omitted in the product lines. So now, the 552 bell became 55 bell as well as the 25 bell that spurred from the 247 bell. The latter sounds the C chord in place of B. On the other hand, other models of 277, 339, and 392 were removed on the product list of Leslie. The remaining models were kept in the streamline while the number is reduced to two digits. During the first couple of months of manufacturing the two-digit bells, the number was printed on the right panel of the bell instead of the left. In the like manner, Leslie produced bells with the number shown in the left.