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Date: May 23, 2002 at 22:18:59
From: Travis C. Vasconcelos, [isbifw1.humana.com]
Subject: Re: What is a "chiff"


Wesley,

A chiff is a shreek or "wildcat" sound made by a steam whistle before it settles down into it's note. Also known as "biting".

There are three situations that cause this.

The First and most common is a slight un-evenness in the cut of the base of the whistle bell. Although usually less than an 1/8"th of an inch, this will cause a "chiff". The repair is the replacement of the whistle bell. If you plain off the suspect metal you can shorten the bell of the whistle. Shortening will raise the pitch. Just 1/8"th can cause a half step, depending on scaleing.

The other situaion which can cause chiffing is drastic and quick changes in steam pressure. This is not common on steamboats. However Circus Wagons experience this from time to time. Ususally caused by the bouncing of the boiler. More common in atmospheric burner systems. Power burners usually compensate well for it.

The last chiffing situation is damaged whistle components. Namely damage or dentiong to the bell of the whistle and/or a bent threaded support rod.

The Str. Delta Queen and IUPUI (Indiana University) chiffs are part of the intrinsic character of the particular instrument. I can tell either instrument on most recordings or in person based on this unique characteristic.

The Str. Delta Queen calliope has gold plating, which substancially mellows the tone. However, in recordings prior to the plating, she and the IUPUI were almost identical, save for the half step difference in the "chiffing" notes.

~Travis~


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