Facebook Page
The Whistlestop

The Whistlestop

Newsletter of the

Great Northwestern Railway


Volume 2, Number 2                                                                                              May 22, 2008


Sound Decoder Test Program


Decoder Comparison Addendum


Study Report


Two new decoders tested!


With the success of the sound decoder equipped locos enhancing the impact of the new rail traffic, two additional sound decoders were acquired for evaluation: one pre-packaged in an Athearn Genesis unit, the other a Digitrax Soundbug installed in an Athearn loco.  The results were mixed.


Athearn MP15AC, Southern Pacific 2746:


Yowza!  This is the machine I most enjoyed doing yard chores out in San Jose as I grew up.  As such, when Athearn offered it, I could not resist!  And what a treat it is. 




Very realistic sound samples make for a very realistic sounding engine.  All the way down to the ‘glug-glug’ as the EMD prime mover notches out of idle!  Athearn also got the volume issue sorted out, and although it is too loud out of the box, it is easy to set to a reasonable level by adjusting CV’s as needed (I used “1” or “0” on all sound volumes). 


Oh, and Athearn pulled out ALL the stops on the light package, including operating gyralights AND the red gyrating warning light.  Having never seen the red light ever operating on the prototype, I wonder how often one would ever need it on a model, but it is there!  The ads are right about the model: in addition to the sounds and lights, the model itself is just exquisite, including a prototypical cab complete with the stands and even the right colors.  Wonderful workmanship. 




For all the great sound on the prime mover, air let offs, and even the bell, they have GOT to start recording some new air horn sounds.  Not a one of them that even remotely sounds right.  Also the starting voltage CV’s don’t seem to let you drop down to a voltage that will allow the machine to ‘creap’.  It just start up at some 5 mph.  Too bad considering I plan to use this thing primarily for yard ops.  Really, no other complaints.





Digitrax SFX064D SoundFX+Function Decoder, installed in an Athearn GP38-2, GNW 2046:


OK, before you read this, realize I am a fan of Digitrax decoders.  Before sound, most of the GNW fleet was fitted with Digitrax decoders.  I really like them, they are bullet proof, reliable, stable, even when track conditions are not perfect, have GREAT lighting features and the like.  When trying out the SFX, I really expected that I would have the perfect combination of electronic performance with excellent sound.  I was further encouraged when I heard a Kato AC4400 at the hobby shop.  Well, I bought one and here is what the test program found:




All the quality Digitrax electronic features one could want.  Stable, even on rough track; great motor control and so on.  Also just LOVE the air let off sound and the various random sounds.  A fun feature in diesel mode is the single button (F7) to actuate the grade crossing air horn sequence of long-long-short-long.




Wow, how could they be so close and yet so far away?!  Explain to me why they would install a delay into the prime mover spooling up AFTER the delay of the momentum passes?  Ya can set the momentum to zero or 20, but the loco WILL move before the sound even starts to rev.  I don’t get it.  Add to that, the sound is sorta funky: it is almost nill for volume when idling, and then way loud when running.  Dynamic brakes are even more whacked out: turn them on, and it sounds like a DC-9 it taking off!  (I know, my model of the GP38 does not have dynamics, but ignore that fact for the moment.)  The horn selections are what I would grade a B; nothing spectacular, but OK.  So is the bell. 


I know that Digitrax is offering downloadable programs, but what if it has some design features that made it sound so bad.  If this time delay function on the momentum/prime mover is a salient feature of the decoder, new sound files won’t make a difference.  Let me know if you know otherwise.  I cannot see investing another $100 into a computer interface just to have it not operate realistically.  Oh, and the CV’s on the decoder are largely inaccessible: they only give you a handful you can manipulate without the interface.


Finally, what’s the deal with Digitrax providing only a 1” 32 ohm speaker?  Do they know how hard it is to retrofit a hood unit with sound with a 1” speaker?!  I had to install it at an angle across the back half of the hood.  That alone took the better part of a day.  Alternately, with the 32 ohm speaker, how can I find a replacement with, say, a 3/4” x 1” size?



Switching Valley Gate.JPG




To: Whistlestop #7                                                   To: Index                                                                                  To: Whistlestop #8