Synopsis: DCC Sound Decoders on DC have many problems.
My club runs a max of 12V REGULATED DC power on it’s layout. I have many sound equipped locomotives that I would love to run on this layout as well as my home DCC layout. Unfortunately I’m running into all kinds of problems.
Soundtraxx tsunami chuff sounds are way out of sync with the actual drivers. However they operate fine in DCC. Tsunami also stutters and chokes if you raise the voltage way too quickly. Top speed is lacking compared to DC version of engine. You also have to keep two sets of CV settings.
MRC (Used in Athearn Genesis) CRAWLS at 12 volts DC. In matter of fact it barely moves. There is no speed table to adjust the curve to speed it up at lower voltages.
QSI (P2K, BLI) is the ONLY DCC dual mode sound decoders which haven’t given me a fit. HOWEVER, even their top speed is a lil off compared to their DC counterparts.
A number of people say that DCC decoders take more juice to run. Personally I’m not buying it. You might increase the amps, but you shouldn’t have to increase the volts to achieve the same top speed. If you put the same model DC locomotive on the tracks, it flys at 12Volts. Blueline trains sound only decoder works perfectly @ 12 Volts with good speed.
And yes I checked the rails with a volt meter. I run consistantly ~12Volts.
So I am of the conclusion that the 12 Volts at the rail are not making it to the motor. This does not make any sense as any parallel circuit delivers the same voltage across the terminal points. The only thing that will increase is the amps. It should be designed like this:
So somewhere the internal circuitry of these DCC sound decoders are cutting back on the voltage delivered to the motor termin
I have never run a Tsunami (or any other Soundtraxx) decoder on DC. Only the QSI, and they take a hefty preliminary crank of the throttle knob before the loco turns a wheel. The sound system uses the first 4-6 volts or so. So, the decoder won’t even talk to the motor until it is getting over 4 volts…at least.
I am not at all knowledgeable enough to comment on the stuttering Tsunami with a rapid rise in track voltage. You have me there.
As for your large paragraph near the bottom, maybe the decoders won’t assign any working amps to the motor until they are in receipt of sufficient voltage to transport the amps? So, they wait until the voltage is up high enough before they open the gate to the motors? Dunno.
I hear complaints about any number of things about all decoders…not one of them seems to please everyone. BlueLine is just the latest kid on the block, and they haven’t found many friends so far. A whole chunk of stickies on BLI’s site dedicated to sorting out “issues”, many of them due to laziness.
Well, the first volt and a half or so get eaten in the rectifier, to start, before the decoder can come to life. And with a motor, it’s really more about the voltage than the current, so you can’t just increase the current. If you increase the current, the voltage drop across the motor goes up, but if the voltage isn’t there, you can’t increase the current. A motor isn’t an LED.
The biggest point is the one David made, it’s a DCC decoder. DC is, in a way, a parlour trick. That they are happy to sell you.
If you have 12 volts on the rails, the most the decoder can apply to the motor is approximately 10.6 volts because of the voltage drop of about 1.4 volts as the voltage passes through the rectifier.
If the DC power has any kind of pulse, or if it lets through a lot of AC ripple, some decoders do not deal with that very well, which may be the cause of the stuttering you were talking about.
Did you check the voltage at the rails with or without the locomotive(s) on the track ? If without, then recheck with the locomotive on the track and the voltmeter not too far from the locomotive. It is possible that you either have some current limiting or source resistance loading down the voltage to the locomotive.
Unfortunately I only have QSI and Blueline sound locomotives so I don’t have experience with the others having problems.
I think it’s going to remain a poor state of affairs for we folks who still prefer to operate our layouts on DC. The sound modules in DC/DCC locos take a lot of power just to get operating, which leaves only about half of our control units to run the locos. I bit on the ‘sound’ system of BLI when they first came out, found out that they were NOT compatable with my other DC non-sound locos, and so I had a choice. I could run the BLI’s exclusively, or my other locos exclusively, but not together. I finally said the heck with it, boxed up all my BLI’s and installed a Soundtraxx “Heartland Steam” speaker system under my layout. I’ve got too many good-running PROTOTYPICAL (and yes, they’re brass) locos for my chosen road to even think about the expense of converting to DCC (besides, all I seem to read on this forum are horror stories about adjustments). So now, I hook up my brass steamers in tandem if I need, turn on the Soundtraxx (which is programmable) and choo-choo all I want.
Perhaps, one of these days, one of the mfgrs will realize that not EVERYONE in this hobby is bitten by the DCC bug and find someway to adjust the amount of power it takes to get a locomotive sounding like it should without pushing us to the last quadrant of our power pack. But frankly, I’m not holding my breath.
It looks like you’re gonna have to get on the DCC train or be left behind at the station [;)]
I can’t imagine having 20 or 30 great looking locomotives that run well on DC and being forced to turn to DCC just to hear great sound. I was lucky my roster was only about 15 loco’s and half those were old athearn blue box’s so no great loss there.
I agree, I wouldnt hold my breath. Remember it takes power to run that speaker and if you wanted the sound to come on at a lower voltage, then the speaker volume would suffer…
You cant have your cake and eat it too.
I find as an employee at a LTS that most people are dissapointed with sound on DC layouts. Most of them who were DC-only activists are comming around and purchasing DCC systems. With our display layout they see how easy it is to operate compared to DC.
Brass steamers only require a remotoring if they run well. What are these horror stories you are hearing about?
David,
As usual, the DCC-in-brass “fear factor” is upon us (the “horror stories” that few have experience with first-hand, but everyone “knows” because that’s what they’ve heard). I’ve converted a dozen or more brass steamers to DCC without any trouble at all. Most of my own brass steam fleet (6 units) date back the 1970’s, some of which have open frame, DC-70 type motors. I’ve also installed DCC in my fellow club members steam, or have watched them do so. Not once have I seen any problems.
Heck, just last night I helped a club member put a DH123D decoder into an Athearn B&M P-4 Pacific…you know, the one that graced the boxcover on the “blue box” for years…the loco that they haven’t made in decades? If any loco was going to overload the decoder or cause problems, you’d think it would be that. Yet it works just fine. It even managed to pull 3.0 oz. on our drawbar tester (which is good for a Pacific).
Sure, brass steam (or old steam) is not “plug-n-play”, but with some Miniatronics plugs and some judicious use of a Dremel tool, it’s not that hard to do.
