Best DCC SOUND for DIESEL / STEAM?

[alcazar]

Interesting stuff.

The original discussion about speakers is what fascinates me, since, as a young man, I researched HiFi speaker enclosures and actually built a few, with spectacular results for the outlay. A friend with even then £400 speakers could not believe how good mine were!

A decent book at the time was G A Briggs' "More about loudspeakers". Briggs was chief designer for Wharfedale before they were taken over by the mass market Rank Organisation.

The difference made by using acoustic wadding to line an enclosure had to be heard to be believed. Much more bass and the whole sound stage became uncluttered and open.I wonder if lining the inside of loco speaker enclosures with medical lint, or similar, might have any effect?

 

[Osgood]

Well I'm getting there slow but sure with a plan for sound, thanks for the advice so far. But just two more questions if you don't mind:

I'd like to synchronise steam sound to wheel revolution - where there is no space for a cam it will have to be magnets in the back of a wheel. Am I right in thinking I have to have 4 per revolution (for a 2 cylinder engine), and can this signal be wired into any DCC chip, or do I need to choose the chip to suit?

 

[Steph Dale]

Tony,

You actually don't need a cam or magnets. You can just do it by setting up a couple of CVs, usually two.
Otherwise, yes; 4 beats a revolution for most 2- and 4- cylinder locos, 6- beats for a three cylinder loco and 8-beats for a Lord Nelson or Holcroft's rebuild of one of the Drummond 4-6-0s (!!!).

It's worth checking what decoder (not 'chip', please!) is of interest and seeing how the synch works. Some decoders don't require to receive a pulse for every exhaust beat, but perhaps only once or twice in each revolution. Most of the better decoders will use Hall effect devices rather than reed switches or whatever, and these can be much more reliable (fewer missing beats).

So saying, I haven't actually used a sound cam or even a magnetic one, preferring to get the decoder to do the work for me - it's potentially a more reliable solution.

Steph

 

[Osgood]

OK thanks for that advice, Steph. More homework then

I had formed the impression that setting the CVs for synch was what gave people most trouble, and assumed it would be easier to avoid them. I'm happy to experiment a bit with the chip decoder parameters and see if I can succeed before giving up.

 

[Dog Star]

I haven't actually used a sound cam or even a magnetic one, preferring to get the decoder to do the work for me - it's potentially a more reliable solution.

Steph, SWD suggests that the Loksound V4 does not need any stimulus from a wheel / an axle to genreate the exhaust beats... and that seems to be true in that the rate of exhaust beats goes up / down in step with the engine speed.

On the other hand, I think that there are a couple of niggles that I have been not able to resolve.

The first niggle might expose my lack of DCC knowledge so any suggestion as to how to avoid the niggle is welcome. I adjusted the exhaust rate by following the SWD procedure of counting wheel revolutions over a distance and then adjusting various CVs - fine... just that the relationship between exhaust beat and crank position is not constant across power cycles.

The second niggle is that adjusting CV values "got close" to matching the exhaust rate to wheel revolution... if the engine runs up and down a plank then the beat "remains" in correlation to the crank position. However, if the engine runs round and round then the exhaust beat appears to drift relative to crank position - I suspect that "got close" is not close enough and the observed drift is cumulative over many, many, wheel revolutions. Thankfully the drift is not enough to worry us at the moment becuase our home layout is end to end.

 

[Steph Dale]

Steph, SWD suggests that the Loksound V4 does not need any stimulus from a wheel / an axle to genreate the exhaust beats... and that seems to be true in that the rate of exhaust beats goes up / down in step with the engine speed.

And that's what I was getting at - my steam locos all use the CVs rather than cams - fewer components, more reliability.

On the other hand, I think that there are a couple of niggles that I have been not able to resolve.

The first niggle might expose my lack of DCC knowledge so any suggestion as to how to avoid the niggle is welcome. I adjusted the exhaust rate by following the SWD procedure of counting wheel revolutions over a distance and then adjusting various CVs - fine... just that the relationship between exhaust beat and crank position is not constant across power cycles.

The second niggle is that adjusting CV values "got close" to matching the exhaust rate to wheel revolution... if the engine runs up and down a plank then the beat "remains" in correlation to the crank position. However, if the engine runs round and round then the exhaust beat appears to drift relative to crank position - I suspect that "got close" is not close enough and the observed drift is cumulative over many, many, wheel revolutions. Thankfully the drift is not enough to worry us at the moment becuase our home layout is end to end.

That's a bit more interesting. I have on the odd occasion been back through motor set up as a loco has run in; as the mechanism frees up the motor will have and easier time and it can be worth re-spinning the drive CVs. In all cases the motor set-up needs to be as good as you can get it; I do this stage with the sound off to make sure I'm concentrating only on the loco's movement. Once that's sorted you can then get in to setting up the sound, including any synchronisation that may be required.

It can take a couple of goes to get the synch perfect, but it can be done. I have the advantage that I can set my locos up on a continuous run, so we get the opportunity to do the sort of extended duration testing you're referring to.

Steph

 

[alcazar]

Is it possible to set a loco up on a rolling road?

 

[farnetti]

Just getting into the world of DCC and diesels. I used to be a sound engineer many years ago and have to agree with Richard Carrs' assertion that bigger speakers sound better. The bass rumble of a diesel engine and the deep 'woof' of a steam engine will always be more convincing with a larger diameter (or oblong) cone. I think the lack of space inside a steam engine is why I have found steam sounds less convincing.

Also sound is just another way to convince the onlooker of realism but it mustn't take over. Think of film with music and 3D. For me film music works best when you don't realise you have heard it, it just enhances the film. The only 3D film I have liked was Gravity because it was so unobtrusive.

Ken