Curious about steam engine decoders

Model Railroader Electronics and DCC
1

Do you synchronize the sound with driver position or does the decoder just make noise regardless of the wheel position?

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Some decoders allow syncing chuff rate to a speed table. Others support an input (wire) from an optional cam mounted to a drive wheel.

google “dcc decoder steam engine chuff sync”

3

I use the settings on the particular decoder to synchronize wheel rotation to speed step setting. I generally use stationary rollers (Bachmann) so I can watch the driver turn as I ‘count’ the rotation. Mainly I’m concerned with the slower speed range where the four exhausts per revolution can be heard with more clarity.
I have two brass engines that came with cams on the driver axle but found the added wiring and fabrication of a wiper to be more of a headache than its worth. Recent decoders do a pretty good job of keeping in synch.

Three cylinder locomotives and some compounds require more tweaking, and most steam decoders have options to choose these if desired. Again, some compounds revert to simple steam exhaust at slower speeds anyway.

Regards, Ed

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I usually sync the sound to the wheels when the engine is moving at low speed. It will go out of sync when it moves a bit faster, but it won’t be noticeable.

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5

Welcome back on board tbdanny

David

6

That is an interesting point. On my steam engines with sound, I have never synced the sound. I always presumed that it was accurate at any speed.

Rich

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It’s supposed to be four beats per revolution of the wheels. So I aim for that.

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Thanks. It has been a while.

I wasn’t aware of the forum swap, so kept trying the old ones.

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9

I read once that BLI steam goes out of synch at higher speeds because they said the decoders produced an unpleasant whirring sound at higher speeds.
With a few notable exceptions, steamers never did run at very high speeds. Limiting a model steamer to what the prototype would run would eliminate the whirring sound.

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Some factory sound steam engines come with the correct sound, as it uses a cam to trigger the chuffs.

Otherwise, unlike a diesel where things are pretty constant from model to model (i.e. F7 vs. GP9 vs. SW-7 all pretty much sound the same), the sound of the steam engine chuffs will normally vary from the default setting of the decoder. Going at the same scale speed, a switcher with 51" drivers will be chuffing a lot more than a passenger engine with 80" drivers, because the smaller drivers have to turn faster to go the same speed as the big engine.

I’ve seen several videos with layouts where the steam engines only have like two chuffs per revolution. BTW that was for many years how Lionel set up their steam engines - or even just one chuff per revolution - I guess because they figured kids would be running them super fast and it would sound better with fewer chuffs at 150 scale MPH!

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Thanks for those additional comments, stix.

Rich

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Out of curiosity, do you recall which BLI engines people said do that? Was the the QSI ones before they did BlueLine and newer? Those one’s did not use a reed switch to time it. But from BlueLine and newer it does. I believe they have CV’s too for settings like turning on articulated chuffing, offset timing on it, steam cock chuff events, etc. I believe they are set for 4 chuffs per revolution out of the box using the reed switch/chuff sensor.

Fun fact too; BLI added CV’s for setting CV based chuffing specifically for me/us because we started putting their newer decoders into older BLI QSI engines, which of course did not have a reed switch for timing. Normally I adjust it to get close to 4 chuffs per revolution when swapping decoders.

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13

tsd,

They’re the very early Paragon locos, before the Blueline came out by at least a couple of years, unless my memory is playing tricks. Those original Paragons didn’t have chuff sensors.

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Wouldn’t Blueline locos depend upon the type of motive decoder added to it? It seems to me that the answer would depend upon that choice.

Rich

15

Pruitt
That is 100% correct and makes more sense to me now. The original Paragon which used either QSI or LokSound decoders (they did actually do some with LokSound) did not have a chuff sensor nor good speed control, if I recall due to MTH being lawsuit happy (was glad when their patent was finally invalidated because they took the idea I believe from Lionel who may not have patented it, I forget). So yeah, I have heard their chuffs get kind of strange. When I swap one of those out to a Paragon 4, I find it usually sounds fine, the only time it can get odd is if you are say running at a good pace and then you cut the throttle down to nothing. It does not know it’s speed then I guess, and it has no signal telling it what speed, so then it just kind of stops playing chuff sounds.

Richhotrain,
Being dual decoder, the BlueLine decoder provides sound. The DCC decoder that you could plug in would be providing motor/DCC but the BlueLine still doing sound. So BlueLine does use a chuff sensor as well, and you can adjust those settings. It’s also why it can be a pain having a dual decoder setup for an engine. Which is why a number of people have sent me their BlueLines to have it replaced with say a Paragon 4, because of being tired of having to mess with 2 decoders at the same time in those engines.

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Yep, I was thinking DCC. Forgot about using the factory installed decoder for DC.

Rich

18

Blockquote I find it usually sounds fine, the only time it can get odd is if you are say running at a good pace and then you cut the throttle down to nothing. It does not know it’s speed then I guess, and it has no signal telling it what speed, so then it just kind of stops playing chuff sounds.

I noticed this effect with the TCS WowSteam 4.6 decoders I have been installing in my Proto Heritage 2-8-8-2 locos. When decelerating the chuff/sound stops well before the loco stops.

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I have the same issue with some bachmann locomotives with TCS wowsound factory installed.

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Ah that’s cool knowing. I only have experience with BLI decoders, so I was not sure if that would be just an “issue” with theirs or not. I know all the newer ones from BlueLine on with the chuff sensor don’t have that issue. But I guess it makes sense that other decoders would if it’s all CV/timing based, probably using back EMF as part of it, etc.