# B'mann K27 & Phoenix P8 - uneven chuffs?



## wigginsn (Jan 9, 2008)

Just installed a Revo and P8 for a club member in a K27 and immediately noticed that 1 chuff was quite a bit out of time, and another chuff was definitely louder than the other three.

I used a transistor to invert the optical signal - hooked a scope across the optical trigger outputs on J1-5 and J1-7 and the source signal is showing the uneven beat. It's consistent across speed ranges so I'm guessing one of the sensors may have moved? Anyone struck this before or found a fix?

Separately, the single accented chuff is quite noticeable, is this a Phoenix 'feature' or just how the real thing sounded? It doesn't sound good to my ear...


All help appreciated.

Cheers
Neil


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## K27_463 (Jan 2, 2008)

Phoenix has the ability to set accented chuffs in the software. in fact they can have 3 different chuff sequences with different accents that fade in and out randomly in random sequences. This feature is to simulate movement of the Johnson bar. No steam engine is perfectly square at all times and in all throttle / valve gear positions. As a result , the chuff beats have variations. With Phoenix programming, you can select from a wide variety of chuff sequences, with single or double accents, and with variations in timing. I regularly set this feature up when programming sound for folks, as it adds much variety and interest and Those people that have repeatedly stated that the chuff is monotonous simply have not used the software to advantage, as this is a great feature. if you do not like it you can turn it off, or select a chuff rhythm that has no accents. The key question is did someone already custom load this p8 board? 

Jonathan/www.rctrains.com


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## Dean Whipple (Jan 2, 2008)

Neil, 
I had the same problem with the BM K-27, to fix it I put magnets on the axle with reed switch on the frame solved the problem....


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## East Broad Top (Dec 29, 2007)

There are two things in play here; first there's the rhythm of the chuff--whether it's "chuff chuff chuff chuff" versus "ch-chuff chuff chuff"--and also the volume of the chuff "chuff CHUFF chuff chuff" 

The rhythm of the chuff is controlled by the flags inside the cylinders of the K. These flags interrupt the optical beam triggering the chuff. When they're in the middle, you get four even chuffs. When they're slid one way or the other, the rhythm becomes less even. Prototypically speaking, a loco with chuffs out of rhythm would be indicative of the valves being "out of square," and would be shopped to correct the problem. Being out of square created an uneven draft, lessening the efficiency of the loco and making the crew work harder. Still, it would be prototypical to hear the occasional out of square loco running down the track. My favorite was Strasburg RR's 1223 (?) which was so far out of square it sounded like a jazz improvisation of "Orange Blossom Special" 

The volume of the chuff is a software issue within the Phoenix. You'll need the programming software interface to get in and make those settings. I wholeheartedly agree with Jonathan here--if you've got Phoenix sound systems, you owe it to yourself to get the programming software. You can tweak those boards to do some _really_ cool things! If you're spending $200 on multiple boards, a one-time expense of $80 to make them really sing is well worth the investment. (That, and you can easily swap out sounds if you get tired of the whistle, or want to move the board from one loco to another.) 

It could also be a combination of the two issues. I've noticed with some of my Phoenix installs that when it picks up on uneven timing between chuffs, especially if you've got the Johnson Bar control set up, it will sometimes emphasize one chuff over another. I've got magnetic triggers on a few locos that trigger evenly going forward, and just a bit uneven in reverse. The volume of the chuff can sometimes sound different depending on which way the loco's moving. 

Later, 

K


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## StanleyAmes (Jan 3, 2008)

Valve gear timing is an interesting property that is seldom modeled. I just got back from fireman's school on the C&TS and was surprised how much the Johnson Bar position effected the square of the chuff. Two of the locomotives fired had a chuff much more out of square then the Bachman K27. Of note the engineers claimed that it did not matter much to the performance of the locomotive except that the one way out of square consumed more water. Having one of these locomotives in perfect square is much rarer than slightly out of square.

The Bachmann K27 is somewhat unique in that it has two chuff sensors, one in each cylinder. Like the prototype it is more sensitive to its square which can be adjusted to provide most any valve gear timing desired.

When we worked on the C-19 a lot more attention was made to having the locomotive in square from the factory. We found two properties needed to be employed.

1) the location on the plastic part that interrupts the sensor on the piston rod needs to be exactly in the center. The plastic part on the rod was made longer so that it would be easy to install consistently. Should the modeler want to adjust the chuff you simply cut this part off.

2) the length of the part that interrupts the sensor needed to be much longer than the one in the K27 to ensure that the chuff on each cylinder occurred 180 degrees away from each other.

These enhancements produce an in square chuff from the factory and allow for the end user to easily adjust the chuff to make the locomotive unique.

On the K27 this is a little harder because the plastic part that activates the sensor is much harder to remove from the rod as it is on real tight

You need to take the front cylinder cover off and move the wheels so that this plastic part is near the front before removing it. Once off you might want to enlarge the hole so that this part can more easily be moved for fine adjustment.

To make the chuff perfectly in square you will have to lengthen the top of this plastic part (to provide exact 180 degree chuffs) and then place it back in the cylinder adjusting each so that they are in square with each other.

I have tended to go the other way making the chuffs more out of square so that the locomotive sound unique and more faithfully recreate the sound of a locomotive that has been in use. 

Stan*
*


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## wigginsn (Jan 9, 2008)

Thanks guys, 

I checked with the owner and the unit was supplied from a Stateside hobby shop and programmed for the 'K. Not your premises Jonathon. Other unusual things are happening such as multiple generator starts at very low speed (part of the uneven timing I suspect..), and bell ringing after accelerating to 35% speed which seems a good trot to my eye.. 

I have the Phoenix software but never really had a chance to play with settings as I don't have a 'puter in my workshop. Guess I'll be having a look at the settings in the lounge, that should please my 2 yr old! 

Thanks all for your input, also looking for a local source for axle magnets now. 

Cheers 
Neil


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## jake3404 (Dec 3, 2010)

I'm right there with you Neil. I had the same exact "problem" with my K. It came up after i used OVGRS's circuit to boost the signal of the optical sensor and switched from my reed switch and magnet combination. 

I was getting the double chuff. I went to youtube and found some videos of the K-27 on the C&TS and noticed that thiers sounded similar to mine so I left it. I'm also getting the bell coming on at about 35% speed which I feel it shouldn't. I have to hook my K up to my computer but just haven't done it yet. I also wonder what everyone's opinion of the "Water fill" sound. It is way to lound and annoying to me. I'm thinking I want to change that sound from automatic to a user triggered sound only.


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## Bob Pero (Jan 13, 2008)

Just got the program software and cable for Phoenix. Can I change the diesel horn sound? Is this an option? Never did this before, and a friend wants a different sound in the diesel that I just did an install for.


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## Robby D (Oct 15, 2009)

Don't use the chuff sensors on the K. reed switch and mags are the most reliable. on some sounds you can change the horn.


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## East Broad Top (Dec 29, 2007)

With the Phoenix, you've got to replace the entire sound file to change horns and whistles. I haven't listeded to the diesel sounds, but there's some crossover on the steam sounds where the same chuff sounds will be offered in two different sound sets with different whistles. Likely the same on the diesel sounds. Have your friend listen to the sounds on Phoenix's web site to pick a horn and motor that he likes. Then go to Phoenix's web site and download the latest version of the sounds (they're the "R9" files.) Plug the board into the little black box, launch the application, then look under the File menu for "Load Sound File" or some such. It will wipe the old file and replace it with the new one. Usually takes around 5 minutes or so. 

BTW, with the software, there are different degrees of control of parameters. For the most fun, click on "advanced" under the Levels menu. Then prepare to get addicted to tweaking sounds. 

Later, 

K


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## Gary Armitstead (Jan 2, 2008)

Posted By Bob Pero on 23 Oct 2012 11:50 AM 
Just got the program software and cable for Phoenix. Can I change the diesel horn sound? Is this an option? Never did this before, and a friend wants a different sound in the diesel that I just did an install for. Bob,

There are "Alternate whistle endings" on steam sounds ONLY. You might try another diesel sound to change the whistle sound. On my Accucraft C19 #346, I actually use the sound file from a D&RGW Mikado #487! I like the whistle better and the sound of the chuffs.


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## TonyWalsham (Jan 2, 2008)

Posted By Robby D on 23 Oct 2012 06:05 PM 
Don't use the chuff sensors on the K. reed switch and mags are the most reliable. on some sounds you can change the horn. 

Adding a small transistor and a monolith capacitor to the socket pcb will invert the chuff signal so the P8 can read it correctly. 
See the first page here: http://rcs-rc.com/PDF/ESC-DIAGv3/PRO-PnP-BKv3.pdf
Far easier than adding a magnet and reed switch. Plus, the chuff will be correctly synced to the piston strokes.


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## K27_463 (Jan 2, 2008)

On many of the diesel sound sets you can change the horn separately. You have a choice of Single chime or muilti chime, so it is not necessary to change the entire sound file if one of the choices meets your needs. 

Jonathan www.rctrains.com


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## wigginsn (Jan 9, 2008)

Tony, 

In this particular installation the signal has been inverted as you describe, the main issue is that the signal from the optical sensors in this engine is not timed very well giving one distinct 'out of square' chuff, the other 3 sounding roughly right but not to the point where I would say they are synced to the pistons - this checked with a scope on the source signal (this is separate to the sound config giving one loud chuff which is easily fixed in software if we choose - looking forward to having a play with that). 

Reading between the lines in the posts above this may not be common but it has been noted and fixed with magnets/reeds in other installs. 

I'll probably head down this path if the owner doesn't like it as it stands. 

Cheers 
Neil


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## Gary Armitstead (Jan 2, 2008)

Posted By K27_463 on 23 Oct 2012 10:39 PM 
On many of the diesel sound sets you can change the horn separately. You have a choice of Single chime or muilti chime, so it is not necessary to change the entire sound file if one of the choices meets your needs. 

Jonathan www.rctrains.com Thanks Jonathan. I didn't know about the diesel horn change. ONLY dealt with the steamer sounds.


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## TonyWalsham (Jan 2, 2008)

I know Neil. 
I was replying to Robby who was saying no to using the stock chuffs. 
I had the odd chuff problem once. Easy fix at the time. Just took off front of cylinders and jiggled the little pcb's back and forth into the correct place. Only time that has ever happened.


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## Greg Elmassian (Jan 3, 2008)

Right Tony, but it won't cure the out of square sound problem, right? 

For those who notice this, the magnets are probably the easiest solution as compared to fiddling with modifying and adjusting the "flags". 

Greg


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## TonyWalsham (Jan 2, 2008)

Understood Greg. 
It happened only the once, right after the K-27 came out. The pcb's just seemed to slot back and lock into the correct place. I'd try that before going to the trouble of adding magnets and a reed switch.


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## Greg Elmassian (Jan 3, 2008)

Gotcha... was more thinking about the newer loco... and was thinking about only the locos with the "out of square" problem... i.e. for those specific locos, then maybe going to magnets is less fiddling. 

Greg


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## StanleyAmes (Jan 3, 2008)

Thought you might enjoy how these locomotive should sound after being used for a time. While this video shows a K-36. The valve gear of a K-27 is the same. Also of interest is how bad the siding track is. Notice how far the locomotive tips to one side.

Stan


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## Greg Elmassian (Jan 3, 2008)

I think most people would take exception to the statement. 

Never heard anyone say that a locomotive SHOULD sound like that, new or otherwise. 

Maybe this is typical how it DOES sound after many years of use and when it is out of tune. 

But SHOULD? 

Don't think so. 

Greg


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