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Digitrax EMD SD70ace, Western Pacific type Sound scheme. Copright (c) Digitrax Inc. July 8th 2007

(C) General Notes

This sound recording courtesy of UP Steam Heritage program (UP3985 had WP#1983 as 'helper' and recorded by AJ Ireland Sept 2005) and Brian Marsh, Overland Models for supplemental recordings at Council Bluffs.

Note: This SD70ace prime mover has significant low-frequency components at idle and low notch settings, so the speaker enclosures should be as large as possible behind the diaphragm to extend adequate frequency response below e.g. 300Hz. This will ensure a more "full" sound that does not appear thin or "tinny".

Each engine recorded has a distinct 'personality', so a particular locomotive example may sound slightly different due to unique e.g. tappet, crank-rate shell vibrations and exhaust-stack differences. Horns and bells are often moved between locomotives, and some roads may change/upgrade prime-movers, or change a normally aspirated engine with turbo-chargers etc.

Recording microphone aspect and location reverberation also significantly affect the final sound scheme.

For CV155=01 ["Semi_automatic Notching"], the Prime mover lowest Notch setting is set by the throttle speed setting. F6 (ON) can increase the Notch and F7 (ON) will decrease the Prime mover to the minimum notch set by current throttle setting.