SD70M vs Dash9

[Anonymous]

I was in one of my fav railfanning perches today, one so close to the track you could almost touch the train, yet completely invisible to the engineer until he's alread past you,....and NS brought in a good sized mixed freight that was mostly chemicals,...headed by an SD70M with 2 more GE Dash 9's rounding out the power. (ALL UP Power)

The train was slowing hard from about 25 MPH, and as the SD70 went by, it sounded like a wind tunnel, compared to the Dash 9's...

Well, my first unqualified opinion would be that I was listening to the fans of the dynamic brakes,.... except that the 2 Dash 9's were comparatively silent compared to the loco in the front.

is this normal (that the fans on an SD70 would be that much louder than a Dash 9)?

[dwil89]

Yes....The EMD's have a roar to them under Dynamic and the GE's have more of a low decibel pitched whistle or whine to them,,,,,Older EMD's, such as the SD40-2 are even louder with the Dynamics....I like the EMD dynamic fan sound better than the GE.....Dave Williams @ [e-mail]