# speed difference in consist



## graywolf06 (Aug 14, 2019)

I have an NCE powercab and am trying to consist an Athearn 911 first responders diesel with Tsunami 2 to a Bachmann GP38-2 with Soundvalue decoder. I was able to consist them but when I place them apart to test their operation I notice that the 911 moves out first at a lower speed step before the GP38 starts to move. They get further separated as they move. When hooked together it looks like the 911 is dragging the Gp38. Any thoughts?


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## Andreash (Dec 30, 2018)

Starting voltage in the Bachmann could be a issue. I just recently picked up a Bachmann gp38, dcc equipped. Try cv2 (I believe it’s starting voltage), and Bachmanns website has some info on cv values that can help. I ended up removing there dcc board, and installed a digitrax decoder. The difference in operation is like night and day. It now moves in speed step 2, verses before in speed step 9 (along with a humming sound). It runs very well now..cheers


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## graywolf06 (Aug 14, 2019)

Thanks for the hint Andreash. When you changed the decoder did it require much modifications or was it plug & play? Which decoder did you use? Thanks, Paul


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## wvgca (Jan 21, 2013)

you -may- have to edit the start voltage, so that they both start moving on speed step one .. the CV for start voltage is CV2 ..


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## Andreash (Dec 30, 2018)

A DH126 by digitrax. A DH 166 will give you more options for lighting. I removed the board, but kept wires from the trucks, and wired new wires to the motor (removed all the sound interference electronics). It’s easy. I also put in new leds by Evans designs.


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## CTValleyRR (Jul 26, 2014)

wvgca said:


> you -may- have to edit the start voltage, so that they both start moving on speed step one .. the CV for start voltage is CV2 ..


This is my holy grail right there: to dial in each loco so it just barely crawls in Speed Step 1.


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## graywolf06 (Aug 14, 2019)

Thanks for all the hints and advice. Should the locos be in 28 or 128 mode for speed step one tuning. Also which mode is the preferred mode for most people?


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## Bwells (Mar 30, 2014)

I'm fairly certain I'm using 28 vs 128, I've never changed it from factory setting. I have a Bachmann non sound and a Bachmann sound value that I consisted. The sound value decoder is way better. Remove the Tsunami from the track. Set cv2 to a value of 20 and see what it does. I started with increments of 2 but changed to increments of 5 and I think I decided 20 was close enough and I was getting tired of it. Let us know.


Edit: My mistake, I see you have the sound value also. That is the one I would try to match to the Tsunami. Try smaller increments like 1 or two at a time. It shouldn't take much.


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## graywolf06 (Aug 14, 2019)

Just an update re the speed differences. I tried the two engines separately to see how they reacted when set at 28 speed steps and the Athearn SD60E with the Tsunami 2 moved out at step 1. The Bachmann Sound Value GP38-2 didn't move smoothly at step 1 until I raised CV2 to a value of 6. I then consisted them and they ran OK except I was hearing some strange noises from the GP38. I doubt if they are a good match for consisting based on the quality differences of the two engines. But at least it was a learning exercise in consisting. Thanks for all your help they run better separately. Paul


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## wvgca (Jan 21, 2013)

at least you have them 'kind of' close, and now you know how to set CV2


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## CTValleyRR (Jul 26, 2014)

Bachmann decoders have been known to make strange noises. That's why I don't use them.

For speed steps, I use 28. I've never felt the need for the fine control of 128.


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## Andreash (Dec 30, 2018)

It’s hit and miss with a Bachmann dcc engine. I’m slowing adding a economy digitrax decoders to my Bachmann engines, and the performance is way better....


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## flyboy2610 (Jan 20, 2010)

Bachmann Sound Value locomotives are equipped with Soundtraxx decoders. The "DCC On Board" locomotives have the el-cheapo no-name decoders that are best removed and replaced promptly.


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## Severn (May 13, 2016)

Just to be bore everyone with possible faux expertise or at least limited expertise. 

The high speed "signalling" these things use to make the motor run (PWM) can be slow enough to hear a whine with the human ear. I imagine the cheaper decoders use cheaper electronic parts -- and so possibly produce slower PWM signals... and that might be one reason some decoders are noisy.

The other reason I've found is that to determine the rpm or estimate it using back emf (bemf), the can motor has to spin a little. This produces a noticeable pause that you can at some power outputs ... and so you might be hearing that.

I have read some claim another approach involves "braking" the motors to get bemf and this may a more sophisticated some decoder take... although I don't have first hand knowledge. (it's possible this is quieter)

Even so, given all that -- I'm amazed any 2 manufacturers can be made to run at the exact speed since bemf appears to be something that's likely to vary some by implementation -- or at least that's the case as it appears to me. (& so estimate of rpm of motor, and so engine speed... )


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## graywolf06 (Aug 14, 2019)

Thanks again for the info. It's quite understandable that an engine that cost me $95 isn't going to have a great decoder in it. I recently did a video of my layout with a Mobius camera sitting in a gondola being pushed around the layout with that Bachmann GP38. There was a noticeable hum being picked up on the audio. I was blaming the fact that the boiler had come on in the basement where the layout is for the cause. Other than the noise the engine works fine for the money spent. I had tuned the CV's such that I added the start up in forward or reverse with the proper horn toots and also the bell ringing on movement and shutting off at certain speed. So I felt that I rung out all that could be expected from the thing. I thought of adding the Econami decoder but I am not sure of the difficulty. 
By the way Flyboy I enjoyed reading your blog --very relaxing.


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## sid (Mar 26, 2018)

i dont like them bachmann's every one of mine are no good. im a kato fan now big time. bachmann's are by them selves sitting . mainly because i have no layout yet. but when i did my bachmann's were noisy and never ran right from get go i even sent them back to get repaired , nothing same ol crap.


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## wvgca (Jan 21, 2013)

sid said:


> i dont like them bachmann's every one of mine are no good.



that's odd .. i have -mostly- Bachmann spectrum geared steam loco, mostly non sound [but not all], and I have very little to no difficulty with them ...
they are set in 28 step mode, with the speed table giving 1 smph per step, enough for geared ..
oh well, to each their own, lol, after all, it's just a hobby


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## graywolf06 (Aug 14, 2019)

I also have a Bachmann 4-6-2 steamer that is a Sound Value and it works fine. I guess I don't hear any hum because the chuffing sound covers it up. I'm happy with both engines overall considering the GP38-2 was only $95. BTW I'm just starting to setup a switching layout to one side of my big layout and am considering the Bachmann GE 70 ton switcher. Any comments pro or con? The $49 cost is very attractive DCC equipt.


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## DonR (Oct 18, 2012)

The DCC Bachmann 70 switcher is a nice loco.
At $49.00 you have a bargain.

My only problem with the loco is that it is too
light. It will slip wheels with only
a few cars as it comes. The innards are crowded
but there is room for extra lead weight. With
that you'll enjoy using it.

For maximum utility, get another and consist them.

Don


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## flyboy2610 (Jan 20, 2010)

graywolf06 said:


> By the way Flyboy I enjoyed reading your blog --very relaxing.


Thank you!


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## CTValleyRR (Jul 26, 2014)

I can't confirm Sid's experience on the Bachmann locos, either. Their DECODERS are not so hot; their locos are very nice and run well.


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## flyboy2610 (Jan 20, 2010)

I have found that the 'soldering', if you wish to dignify it with that word, on the Bachmann DCC Equipped locos is less than stellar. If I were going to purchase the Bachmann 70 ton DCC Equipped loco, I would also purchase a Digitrax DZ123 decoder and install it.
http://www.digitrax.com/products/mobile-decoders/dz123/
They are small, but work well. Make sure you check the stall current on the Bachmann loco first. I replaced a Bachmann decoder in an 0-6-0 with one of these and it runs great! Of course I also added pickups to the tender wheels.


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## spikedrivingblues (Dec 11, 2018)

I consisted my first two engines not long ago. In addition to adjusting cv2 you may also need to adjust cv5 and cv6 (I think those are the numbers). This will also match them at mid and high speed. Check your owners manual but I think cv6 is mid speed and cv 5 is high speed.

Speed matching beyond those 3 CVs are not in this beginners purview


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