28 vs. 128 speed steps

[rrinker]

 I guess I'm not getting it - if I understand the way you are explaining what he told you, if you use 28 speed steps with momentum programmed in, you can just quickly crank the throttle to step 28 and let the momentum handle the acceleration rate.  The exact same thing would happen in 128 speed step mode. You are correct about the ballistic tracking in the DT400 - crank the knob fast and it goes from 0-100 pretty much instantly. But the same thign would happen with a UT4 or with the throttle on the Zephyr console - immediately move it to maximum and the loco will accelerate at the programmed rate and you'll get the same sound effects assuming the decoder does the acceleration sound thing - like QSI. Also with any other DCC system I'm aware of - if the decoder has acceleration and decelleration values set, moving the throttle from off to full on immediately, or shutting it down quickly, will result in a gradual speed up or slow down at whatever the programmed rate is.

 Perhaps if you compeltely turn off ballistic trackign in a DT400 - it can take a coupel of turns to go from stop to full. That's a personal preference but pretty much everyone has ballistic tracking on their computer mouse - with a higher resolution screen it would be nearly unusable without ballistic tracking. I definitely keep it turned on on my DT400 - want to accelerate slowly, just turn the knob slowly. A good habit to be in becuse if you get used to just cranking the knob full on and some day are controlling someone else's loco that doesn't have a nice slow accel rate programmed in - look out!

                                             --Randy

 

[MRRSparky]

Let me explain why I "bought into" the author's recommendation to use 28-steps: I use a Zephyr system with a DT 400 throttle. When I access any decoder from the "stack,", a message displays giving the operator the option to use 14, 28 or 128 speed steps. There might also be a setting for European decoders. It is changeable by repeatedly pushing the "Edit" key to get to the method you want to use, so I'm assuming this information is kept in the command system, not in the decoder. What I got out of the article was that if you use 28 speed steps for a steamer, you can advance the throttle more quickly to take advantage of the long acceleration/deceleration times the author sets in CVs 3 & 4 when the loco operating in BEMF mode. With the DT 400 set to ballistic tracking, this may not be an issue. A second reason I asked the question is that one of the local hobby shop owners recommends 28 speed steps. He is reasonably knowledgeable about DCC (giving lots of clinics on it) AND he is an MMR. I tend to listen to what he has to say. Of the five model train hobby shops in the area, one owner is knowledgeable, two are kind of knowledgeable, and two no nothing about it and don't stock it. Very conservative area, the Pacific Northwest.

[ClinchValleySD40]

I run close to 200 locos on my layout and use 28 speed step for all.   Great sound and switching response, would not consider 128.

[cacole]

Decoders themselves have only 28 speed steps.  128 speeds steps is controlled by the DCC system and is merely extrapolated from the 28 speeds that are actually programmed into the decoder.

 

[jrbernier]

Scott,

  Give it a try, but remember that what you are reading is one persons opinion.   And that may be with a limited selection of engines.  If you plan to 'double head' your engines, the 128 speed step will smooth out the differences.  Trust me on this.  A friend had a pair of Stewart/Kato engines that ran great together on DC.  After installing two identical decoders, the would not MU worth a darn.  I finally  started looking at the problem and found that he had changed one decoder to 14 speed step mode.  Changing it back to 28/128 smoothed out the engine and it would run fine.  I will have to read that article tonight.

  Well, I have read it and am somewhat confused.  I thought you were talking about 14 vs 28/128.  The decoder is normally shipped in 28/128 mode - CV29 usually is used to configure what speed step and if you are using speed tables in the Tsunami decoders  There is no way to change the decoder itself between 28 and 128 that I am aware of.  All the author mentions is that he is using 28 speed steps - which is 28/128 on most decoders.  You do have the option to change it to 14 speed step operation with CV29, but I am sure your motor control may suffer.

  Depending on your DCC system, you may be able to 'force' ALL decoders to use only 28 speed steps.  On a Digitrax Super Chief(DCS100), there are ops switches that can be set to limit one to 28 speed steps.  You might want to send a email to 'Scale Rails' and have them forward it to the author about exactly what he is describing.  For me, losing 128 speed step and extended FX lighting function is not worth it.

Jim

[MRRSparky]

Question: which of these two do you use? Why? Personally, I've always had my decoders (Soundtraxx, LokSound, TCS) set for 128 speed, taking Digitrax's word that this provides the best train control. Now I read an article in NMRA's "Scale Rails" about how to really set up a Soundtraxx Tsunami for steam locos; therein, author feels 28 speed steps provides the better sound control. So I am considering reprogramming my two Tsunami steamers, following his recommendations. BTW, this article is the most valuable I've ever read in any "Scale Rails," bar none. I'd gotten pretty fed up with the endless detailing of the requirements for earning the MMR designation.