I am installing a Digitrax SDXN136PS Sound FX decoder in a (quite old but still working well on DC) Bachmann 2-6-6-2. Several years ago SoundTrax put out a paper that detailed how to do this with their DSD-090LC decoder which, I have been told, is no longer available. Hence the Digitrax.
I know I will have to create a speaker plate to hold the speaker underneath the coal load through which are drilled #65 holes. I believe my construction skills will allow that.
What I am unsure of is how to connect the decoder’s 8 Pin Easy Connect harness to the Bachmann harness in the tender. It would be unthinkable that they mate, so I believe there are several options:
1) Find a harness that mates with the Bachmann hardware and hardwire the decoder’s leads to it, making sure they all match
2) Finding a harness that mates with the Digitrax hardware and hardwire the Bachmann leads to it, making sure they all match
3) Losing both harnesses and hardwiring the leads from the tender to the decoder, making sure wires match.
Options 1 and 2 involve searching for items of which I have no clue.
Option 3 involves soldering techniques which I can handle, placing a small piece of heat shrink over one lead, soldering the two wires together and using a heat gun to insulate them. Does that work? How does one determine the connection is good, i.e., can I use a continuity tester without harming the decoder?
Or, is it acceptable practice to solder the tender’s leads to the male side of the Digitrax harness? I got a lot of practice doing this with the header pins which Forum members steered me to for control panels, though things are a bit tighter here on the harness.
And I only need to link six leads between the decoder and the tender: black/red for power pickup, orange/gray for motor leads, and white/blue for headlight. Correct?
Finally I believe I’m okay with creating a baffle for the speaker, probably a soda cap with a small notch in the side for the wires, sealed with silicone sealant. But, and here’s the final question, what is the best practice for attaching the speaker itself to the styrene speaker plate positioned underneath the hole? Does it need to be glued/caulked to the styrene or can it just sit inside the baffle and do it’s thing?
I would never have thought of doing this conversion six months ago, but I think I’m ready. And I need this unit on my layout: it’s a Wheeling and Lake Erie unit and I found out that my son-in-law’s grandfather was an engineer for W&LE back in the days. Though I doubt he would have been an engineer back when steam was still in use. Still, I’d like to see his eyes light up. Thank you for your help here.
Robert
PS. What am I missing? (Which, as always, is just about the most important question anyone can ever ask.)
Hello, Robert
My only Bachmann steam is a pair of their B&O EM-1 2-8-8-4s that were originally equipped with their stripped-down Soundtraxx decoder. Not long ago I pulled all this out and replaced the speakers and decoders using a Scale Sound Systems Big Boy speaker and a TCS WOWsound steam decoder.
I've done dozens of DCC sound upgrades on steam, mostly Broadway Limited, and my prefered method is to completely gut any existing boards and start from scratch but generally retaining the engine to tender wire harness.
The EM-1's tender looked like this:
EM1_BnO-tender-DCC2 by Edmund, on Flickr
Plenty of room to work with. In the case of Bachmann I remove their RF choke across the motor leads as it can hamper a decoder's BEMF motor response.
In the case of your USRA tender I believe the coal load is removable. In some cases I've mounted a speaker in the coal space when room is tight. Sometimes I retain the coal load and drill dozens of small holes through it to let the sound out.
I've tried to make a 'Western Union' splice with the fine decoder wire before soldering but this has proven to be difficult and not really necessary. What I do now is place a small length of heat shrink on the longest side then twist the stripped wires as if you were going to put a wire nut on, then solder.
Sometimes the heat of soldering will further shrink the insulation. Then I clip off any extra length of the soldered joint, fold it back then slide the tubing in place and heat it to shrink.
A soft drink bottle cap doesn't seem like much of a speaker baffle unless you're talking N scale? I try to fit the largest speaker in there as possible.
Did you already buy the Digitrax decoder? They would be my last choice for a sound decoder as far as 'quality' of sound output. I've used Loksound Select and Tsunami 2 in the past and both of these aren't quite the best in steam sounds, either, IMHO.
TCS WOWsound, to my ear, has the best exhaust sounds available as far as I can tell. Again, this is subjective.
You might pick up some pointers in this video.
I haven't watched the whole thing but when I get a chance to later I'll comment on anything addressed in the vid.
Don't forget at least a 1KΩ resistor for the headlight! (I have, more than once)
Good Luck, Ed
There is room under the coal load to add a large speaker. I originally tried that on mine, but the sound quality was so-so. I ended up removing the metal weight and drilling holes through the plastic floor of the tender to add a 1" speaker and enclosure facing down. I then used some of those 1/4 oz "peel and stick" square weights to replace the weight lost by removing the flat weight.
I second the idea of using a higher quality decoder, like WowSound or Tsunami / Economi, or even ESU. BTW when you're setting the 'chuff' sounds, these engines were true Mallet double-expansion engines, so just made the usual four-chuffs-per-revolution; don't use the articulated double-chuff sound.
The Bachmann Spectrum 2-6-6-2 was the second locomotive that I purchased, and the first steam locomotive that I purchased back in 2004 when I first got into scale modeling. This thread, short as it may be, has inspired me to add sound which I have wanted to do for 24 years.
Rich
Alton Junction
wjstixBTW when you're setting the 'chuff' sounds, these engines were true Mallet double-expansion engines, so just made the usual four-chuffs-per-revolution; don't use the simple-articulated double-chuff sound.
However: be advised
(1) that the exhaust of a Mallet compound will be softer and somewhat more protracted than 'one engine' of an equivalent simple articulated; and
(2) at starting, when the intercepting valve is open, the engine WILL have two sets of exhaust beats at the stack, and very likely the two of them will not sound the same. "In principle" an intercepting valve should be reducing the boiler-pressure feed to the 'correct' MEP to match the LP TE with the HP... but some manufacturers seem to have wanted the Greatest Possible Starting Tractive Effort, so just piped full pressure to the larger area, probably reasoning it was only to be used at starting or very low cyclic. My guess is that unloading of the suspension combined with massive torque on the then-unloaded forward engine would create the possibility of heroic-grade slips in a wide variety of cases... which might be fun to model, along the lines of that Lionel F-unit with the 'defective' sounds...
ROBERT BRABAND1) Find a harness that mates with the Bachmann hardware and hardwire the decoder’s leads to it, making sure they all match 2) Finding a harness that mates with the Digitrax hardware and hardwire the Bachmann leads to it, making sure they all match 3) Losing both harnesses and hardwiring the leads from the tender to the decoder, making sure wires match. Options 1 and 2 involve searching for items of which I have no clue.
Go with option 1! If you're going to be in DCC you need to get familiar with harnesses, since that is how you connect a decoder to an engine.
Before the recent addition of 21-pin decoders, 8 or 9 pins were standard. Most models made after about 2000 (like your 2-6-6-2) have an 8-pin receptacle. A decoder with eight pins will just plug into it, several manufacturers have made those.
Many decoders, including sound decoders, usually have a 9-pin connection.
Harnesses have a 9-pin female connection on one end, and an 8-pin male connection on the other. You plug the 9-pin end into the decoder, and the 8-pin into the receptacle in the engine. There are many harnesses with different lengths of wires and orientations of the 8-pin plug, so finding the right one isn't that hard.
In this case, the older Bachmann engines used a "UK" receptacle, meaning the 8-pin receptacle is turned 90-degrees from the usual way a US engine would be. That means it will be easier if buy a "UK harness" for the connection. Another harness will work as far as power, but may be harder to get to easily fit inside the tender.
This may all sound complicated, but it's many MANY times easier than ripping out the lightboard and trying to hardwire / solder all the connections.