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Double-chuff?

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Double-chuff?
Posted by wobblinwheel on Friday, January 12, 2018 6:37 PM

I was just watching a video demonstrating a BLI Y6b locomotive, and it clearly had a "double-chuff" sound through out it's operation. I was wondering, since the Y6 was a COMPOUND locomotive, would you still hear the double-chuff?  Since the rear cylinders exhaust through the front cylinders, wouldn't you only hear ONE SET of chuffs? I know, on start up, the Y6 COULD be in "simple mode", but only for a short distance. Am I right on this?

Mike C.

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Posted by 7j43k on Friday, January 12, 2018 7:35 PM

They got it wrong.

And you are correct.

 

Ed

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Posted by gmpullman on Friday, January 12, 2018 8:06 PM

wobblinwheel
I was just watching a video demonstrating a BLI Y6b locomotive,

One of the downsides of many of the videos out there, weather on Youtube or a commercial DVD is that the sound has been dubbed from any number of sources, not always matched to the particular locomotive or scene being portrayed.

I had posted some old 8mm films that I shot back in the 1960s and '70s and some of the comments I got were, "Great video but the sound is broke".

Unless the photographer had "sound-on-film" or a recording engineer with synchronized sound recording equipment, chances are the video you saw had dubbed sound.

Better than nothing, I guess, but not necessarily accurate.

Regards, Ed

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Posted by Overmod on Friday, January 12, 2018 8:38 PM

wobblinwheel
I was just watching a video demonstrating a BLI Y6b locomotive, and it clearly had a "double-chuff" sound throughout its operation.

You are correct that the double-chuffs would only be heard during 'simpled' startup, and even then the ones from the lead engine would be different from the ones for the HP.  It might be interesting to consider the modifications to a sound chip to implement speed-sensitive simpling.

More likely, they simply (no pun intended) adapted the sound setup from their Class A, a prototype which is famous for producing desynchronized 'double licks' throughout its speed range.  (I have just bought one to test whether its setup actually reproduces the prototype or just has multiple chuffs timed off some sort of sloppy rotary encoder like the old four-sided nut cam)

 

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Posted by selector on Saturday, January 13, 2018 12:20 AM

Overmod, if it's an earlier version, say by BLI in their Paragon or Blueline versions, it will be strictly a BEMF-sensitive chuff that you can manipulate at a given speed and hope it stays relatively synched at higher speeds.  By the time they got around to Paragon 2 and beyond, I believe BLI resorted to a reed-switch and magnet arrangment which has an iffy reputation for robustness.  I mean, when it works, it's great, but quite a few failures have been reported, generally a couple of hours into its use.

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Posted by wobblinwheel on Saturday, January 13, 2018 1:27 AM

I sent the Loksound decoder from my original PCM version of the Y6 to a fellow with a "Programmer" to change the sounds. Using soundfiles from British, German, and who knows what else, we actually came up with a "compound" chuff that starts with a double chuff for around fifteen wheel revolutions, then shifts to a single chuff from then on. Then we changed the pitiful PCM whistle to a British "hooter" that sounds great, compared to the "moaner" originally installed! I dare say my PCM Y6 doesn't sound quite like any other out there.....

Mike C.

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Posted by 7j43k on Saturday, January 13, 2018 10:08 AM

That sounds like an interesting bit of work!  I think I would have wimped out and just put in a "non-articulated" sound.  I believe the compounds had a less-sharp exhaust, so, if I could pick-n-choose, I'd head that way.

The simple start is an intriguing inclusion.  I think it was switched on by intention by the engineer.  So it didn't always happen.

The ideal, for me, would be to have a function switch that could do what the engineer does/did.

I'm lucky, in a slightly disappointing way, to follow railroads that didn't have compound articulateds during my time period.  But I HAVE heard some really disappointing "regular" articulted sounds, where they emphasize the lack of engine "synchronicity" WAY TOO MUCH.  It sounds like one driver set has smaller diameter wheels, or something.

And, as long as I'm whining/complaining:  I'm not too fond of being forced to have sounds coming out of MY steam locomotives that indicate the valve timing is off.  I like to think that my shop crews are on top of the matter.  It may sound "cute" and "clever", but it gets old.

 

Ed

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Posted by wobblinwheel on Saturday, January 13, 2018 11:06 AM

Ed, when you say "valve timing is off", what do you mean? What does that sound like? Is that something some manufacturers "incorporate" into their sounds?

Mike C.

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Posted by 7j43k on Saturday, January 13, 2018 11:30 AM

A properly timed steam locomotive will have four indistinguishable chuffs for every driver revolution.  There should not be one that is louder or "different" than the others--no "I think I can" with the emphasis in "think".

 

Yes, they do incorporate it.  That's why I'm hearing it.  All too often.  

It's just fine to have it in a back-woods 2-8-0.  I guess.  But in a modern 4-8-4--I don't think so.  

PERHAPS some of them give you various sound options, and you can pick a different (better) one.  No problem here with that.  But it's ridiculous to offer that as the only one.  For that matter, it's ridiculous to offer that particular choice on an engine where it's inappropriate.

 

Ed

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Posted by rrinker on Saturday, January 13, 2018 11:48 AM

 I think more often than not, that is an artifact of recording the sounds and getting them set up to play with some amount of attack and decay and not just a sudden burst of sound, and then stringing it together to play a 4 chuff sequence. Since the samples can'e be a whole cycle (how would you change chuff rate for speed then, make 60 sets of samples, from 1 mph to 60mps in 1 mph increments?) what you get are 4 distinct chuffs with just the slightest gap which gives the cadence you end up hearing. It would, I expect, take an outstanding sound engineer to get it so that at no speed throught the loco's range, there is zero gap, especially before the first chuff. Some people have learned the hard way that editing sounds for a sound decoder isn't all that easy, as they end up with an audible 'click' in their whistle sequence or similar. 

                            --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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Posted by Overmod on Saturday, January 13, 2018 12:32 PM

7j43k
It's just fine to have it in a back-woods 2-8-0. I guess. But in a modern 4-8-4--I don't think so.

You hear it all the time when the steam tract isn't maintained properly or one of the valves has more 'blow' than the others.  I've always thought that a good sound system ought to be able to be 'tuned' to produce a variety of typical failing-maintenance effects (I may be one of the few modelers who actually loved the idea of the 'failing F unit' that was marketed a few years ago) since a perfect foursquare exhaust with equal beats is something unlikely to persist long without periodic (and by the late '40s, increasingly expensive and specialized) maintenance.

With respect to 4-8-4s, and one locomotive in particular, I remember a comment in Trains many years ago now about some C&O power that had a very different sound on every fourth exhaust beat -- the prose described it as "chow-chow-chow-wheep".  They didn't know the reason for that, and I still don't, but I suspect it would be clearly audible in sound samples.  And once we figure out what causes it, perhaps in other applications as well.

Of course it's also ridiculous to use the same sample for multiple speeds: as the locomotive reverser is notched up, a number of characteristics of the exhaust will be changing.  In a sense this is more important than 'synchronizing' the sound with the mechanical motion, as most people won't be able to figure this out considering the relatively high cyclic rate of the motionwork at any meaningful road speed plus the effect of 'speed of sound' over typical model viewing distances.

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Posted by 7j43k on Saturday, January 13, 2018 2:36 PM

Overmod

 

 
7j43k
It's just fine to have it in a back-woods 2-8-0. I guess. But in a modern 4-8-4--I don't think so.

 

You hear it all the time when the steam tract isn't maintained properly or one of the valves has more 'blow' than the others. 

Well, yes.  But you don't hear it with a properly maintained locomotive.  I have nothing against having and running "ragged" exhaust sounds.  I just don't see them as a logical first choice.  Just as I don't see the sound of a nearly dead F unit as a first choice.  Or, worse, the ONLY choice.

 

Ed

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Posted by selector on Saturday, January 13, 2018 5:46 PM

Overmod

 

 

With respect to 4-8-4s, and one locomotive in particular, I remember a comment in Trains many years ago now about some C&O power that had a very different sound on every fourth exhaust beat -- the prose described it as "chow-chow-chow-wheep"...

 

I noticed that 'squeak' sound on the xth chuff of WP&YR's #73 in the summer of 2016.  It was also picked up by my Panasonic camera's mikes.

As you describe it...

"Wheeep, chuff, chuff, chuff, wheep, chuff, chuff, chuff..."

My suspicion is that the disparate chuffs we hear of various types may seem louder, but really they're just different, and are perceived as more salient and more energetic/louder solely because of their difference.  Like you, though, I am stumped by this squeak.

Meanwhile, I have an emailed inquiry sent to the scenic railway.  We may get lucky if the hogger replies.

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Posted by Virginian on Saturday, January 13, 2018 8:04 PM
On Simple articulateds the double chuff would go in and out of synch as the front engine would almost always slip more than the rear under load.
What could have happened.... did.
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Posted by 7j43k on Saturday, January 13, 2018 8:35 PM

Virginian
On Simple articulateds the double chuff would go in and out of synch as the front engine would almost always slip more than the rear under load.
 

 

 

What I hear is a continuous slip, then.  I hear it coming in and out of phase.  It sounds exactly like one engine has smaller drivers.  All the time.

 

Is that what you're describing?

 

Ed

 

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Posted by wobblinwheel on Sunday, January 14, 2018 12:10 AM

I really can't stand the constant "NOT random" slipping in-and-out of the sound-equipped four-cylinder locos that have. After having some of these locos for years, and not liking that aspect of the sound, AND the fact that at higher speeds, the out-of-sync chuffs sounded like a jumbled up MESS! I finally decided to remove the axle covers under one set of drivers, and reset the driver position to match (or very close) the position of the other drivers. I then adjusted the sound to eliminate the double-chuff. I'm much happier now with the sound, and they clearly sound better at higher speeds! No need to have the SOUND go out of sync, when the drivers DON'T... EDIT: I forgot to mention, those who may have the "old" BLI locos with the QSI decoder, you might think you can't disable the second chuff. Well you can, using the CV that controls the volume of the SECOND chuff. On mine, I adjusted the volume of the second chuff very low, until it sounded like a slight "echo" that would drift in and out. Very neat effect....

Mike C.

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