DCC Chuff rate for HO 3 truck Shay

[Paul C.]

I have installed the Soundtraxx DCC decoder made for the HO Bachmann Shay. I want to set the chuff rate but I need two pieces of information to use in the Soundtraxx chuff rate calculation. These are wheel diameter in scale inches and the gear ratio. They are probably readily available but I haven't been able to locate this information. Does anyone know these values?

[drgw268]

Don't have the info you need, but I do have a quick question about the soundtraxx shay decoder itself.  Is your volume very faint?  I installed one for a club member, and can't get any appreciable volume out of the thing.

[r0bert]

a shay is a differnt animal, it's not the wheels, but the drive shaft that counts. there would be two chuffs per cylinder for each time the drive shaft rotates thru 360 degrees. the Bachmann shay has three cylinders, so that's six chuffs per revolution of the driveshaft.
I would probally set the rate at the highest possible rate, and work down from there

[VTBob]

I have one.

I set my CV values to:
CV 115 ----- 0
CV 116 ----- 120 (possibly from 120 - 175) Play with this one till you get what you like
CV 120 ----- 200
CV 122 ----- 225
CV 123 ----- 150


bOB

[Paul C.]

Thanks for input. I'll check my current the CV settings against those provided. I did set the rate by watching and listening.
Why I wanted the gear ratio and wheel diameter is that soundtraxx has a formula in their manual for chuff rate. CV =115.9 x (top speed in scale mph / wheel diameter in scale inches) x gear ratio. For side rod  locomotives the gear ratio is 1.  I'm hoping this does result in 6 chuffs per drive shaft revolution for the shay.
As for the question about volume. It's been some time since I've run it but believe the volume was sufficient. It did get a little muffled when I put the "sound transparent" coal load in the bunker. I used some packing foam (like in the locomotive box) that is not very dense. So may have to adjust the volume. I won't get to run it till next monday evening and can report back with better information.
R/ Paul C.

[kenp]

Did you guys use the Micro-Tsunami, or the full size? And where and how did you install the speaker?

[BigBob1]

Greetings!

FWIW, I just installed a mini-Tsunami in a 3T Shay & it went pretty well. I installed it & the speaker in the rear tank; I drilled a couple holes in the bottom for the speaker after disassembling the tank completely. I used an N-gage spkr. which fit well. The tricky part was salvaging the old circuit board so I could use the existing wire connectors between the tank & the locomotive. I ended up sawing off about the front 1/3 of the p/c board & soldering the decoder wires to it. This way I didn't have to rewire the whole engine & there are no new wires showing. As for the Chuff Rate, I set CV 116 (?) to around 160 & it seems pretty close. This will probably be different for each engine so you just have to guesstimate it.   My only gripe with the mini-Tsunami is that the whistle doesn't get very loud, but the bell can blow your eardrums out if it's up to full volume! She's a nice-running loco.     Bob Battles

[Paul C.]

for drgw268 - In running my Shay on a friends layout last evening I did find the exhaust volume a bit low. However I did change the exhaust volume (CV122 to 240) and felt the sound level with the foam coal load in place was just fine. Good appropriate volume level with locomotive about 10 ft away. The Whistle volume CV 120 remained at 192 and the bell volume CV121 remained at 128 and air pump CV 123 remained at 75. We did have one other locomotive present that was having volume problems which after investigation seemed to be from extra paths for the sound to get out of the tender and small or not enough speaker holes.

for Kenp - I used the Soundtraxx DSD-B3TSLC which was made specifically for the Bachmann 3 truck Shay. It has a plug in board that installs in the water tender and the small oval speaker installs in the coal bunker.

All: The discussion has mainly been about the chuff rate. Well last evening I used the programming track on my friends layout. He has equipped the programming track with locomotive "rollers". So the engine could be run in a stationary position. Also we had a laptop with the Decoder Pro software so all sorts of Decoder functions etc could be looked at,  tried, and eventually programmed and recorded in a data sheet. Well we tried a number of CV 116 settings. I previously had CV 116 set at 45. So we changed it to 120 and a couple of us counted about 10-12 chuffs per revolution of the drive shaft. So after trying a few other settings we settled on setting CV 116 at 60. A couple of us counted 608 chuffs per revolution of the drive shaft. We then ran the locomotive on the layout and this setting seemed reasonable given the locomotive speed and our memory of our rides at CASS Secnic RR. So my present settings are CV115-1, CV116-60, CV 120-192, CV121-128, CV122-240 7 CV 123-75 and I'm happy with them.
     Of course, I'm still hoping someone,somewhere knows the wheel diameter and gear ratio that I originally asked about and will share that with us as I'd still like to see what the Soundtraxx formula gives for a result.
R/Paul C.

[kenp]

To Paul C.
Seems Soundtrax no longer offers this decoder, just F.Y.I

[Eman627]

I don't know if you guys are still monitoring this topic, but from my research, using the soundtraxx chuff rate formula, 115.9 X top speed / driver diameter X gear ratio, the proper chuff rate setting should be, given that the prototype of the Bachmann 3 truck shay, Cass shay#5, has a top speed of 13 MPH, a gear ratio of 2.056, and 36 inch drivers, equals a chuff rate of about 86. Where I got the gear ratio and driver diameter is here: http://www.shaylocomotives.com/data/dataframe.htm (Click on 1500 to 1700, then click on sn-1503)

[Doneldon]

I put a speaker diagonally in the tank and let the sound out through the bulkhead between the tank and cab. That allowed a somewhat larger speaker and still kept a good baffle behind the speaker. I suppose you could port the sound through the wood or coal load in addition to the bulkhead which would allow a little more volume. But I get enough for my taste just through the bulkhead and you really can't tell the holes are there unless you go way out of your way to see. I doubt anyone would ever notice it without explicitly looking. If one is really concerned about it, you could put a black fabric cover over the holes.

                                                                                                                                            -- D