Digitrax SDH166D Sound Decoder: A Review... of sorts...

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KB02

Well-Known Member
As I have finally made my foray into the world of DCC with sound, the first decoder I bought happened to be the Digitrax SDH166D. I figured that I would do a quick review of the decoder here so that others who may be looking at it may know my experience with it. Let's be honest, I bought this decoder because I am cheap and so was the price. I am certainly not unhappy with it, but there are a few things that I would like to change if I could. Again, as I go into this, bear in mind that this is the very first sound decoder I have ever owned.
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DIGITRAX SDH166D - AN ENTRY LEVEL SOUND DECODER AT AN ENTRY LEVEL PRICE:

SDH166_jpg_200x200_q85.jpg

There are two things that drew me into buying the Digitrax SDH166D: 1.) It came with a speaker; 2.) THE PRICE! I picked up this decoder for about $45 on eBay (Suggested retail price is still only $55). One certainly cannot argue about the merit of a good deal, but one also needs to keep in mind the traditional old sales slogan, "You get what you pay for." When you keep in mind that I picked up a five pack of non-sound decoders for just a little bit more than this One sound job, $45 isn't unreasonable.
Once I committed to the purchase, I THEN looked to the online reviews and YouTube videos to see what other people thought and to see if I had just wasted my money or not. Kinda did that one backwards, but I feel it worked out in the end. Here are some things that I have found as I have played around with this decoder that you could put into the back of your mind if you are considering buying one as well:

Comes with two preloaded sounds: A Steamer or a GP38.

As it turns out, I was putting this into a GP38-2, so it kinds of works out well. You can download all kinds of sounds from Digitrax's library and load them into the decoder if you have the proper program, cables, etc... which I don't. If you have a different loco, you might end up with the wrong prototypical sound unless you spend the extra to change it (or know someone who can do it for you).

Prime Mover sound is kind of quiet... but that's okay!
As I looked at different videos and reviews of this and other decoders, one of the first thing that just about everybody said or did was turn down the volume on the Prime Mover sound. As it turns out, the PM volume isn't that loud on the SDH166D. At first I was a little disappointed, but after I got to thinking about it, I probably would have turned it down to where it is now anyway so, once again, I was saved a step.

Quick Start-Up, but no Shut-Down
Probably my biggest, and nearly only, complaint about this decoder is that there is no Shut-Down sound or way to turn it off other than a Mute function (F8) which only quiets it... you can still hear it. So, If I just need to move the loco to a different track to get it out of the way while I work (play) with another loco, I then have to listen to it sit there and idle the whole time until I turn the power to the track off. The Start up sound is pretty quick in comparison to others I have heard, but that doesn't bother me too much.

Other than that, I am pretty happy with the purchase. It is certainly not a Bose Quality speaker, but what do you want for $45 for the whole kit & Caboodle? I dropped it into an Athearn Blue Box Loco, so it works for what it is. So, on a scale of 1 to 10, I'd give it a 6.5. Maybe a 7. That rating may change as I get other and play with other decoders. For now, though. I'll stick with it for a while.

Hope this helps.
 
Thanks for the Review, I'm in that boat in that I've not had sound in any loco I've ever owned. Currently ive been tinkering with silent decoders for a few months and I'm now starting to get a grasp on them. I ended up installing three DH165AO decoders into the trio of BNSF locos I have and was pretty happy them. I also did a little research and saw that they can have sound added rather easily using the Digitrax SoundBug. I think the rub for me comes when I need to switch the sound profiles because like you I'm not set up where I can use a computer to mess with CVs. That is one area I am certainly interested in exploring as I'm in IT as a career, but just haven't taken the plunge yet. This week I plan to pick up a couple of Tsunami decoders for the EMD 567 PM and throw them into my new Genesis locos, so that will be my first foray into sound. Might also snag a soundbug or two since the local hobby shop has their weekly special this week as 20% off DCC and Electrical.
 
If I remember right, you double tap F9 3 separate times to enter each stage of shut down. The final stage is the doors closing. Then to start it back up you double tap F6.
 


I'll give that a try, but Digitrax Tech Support said there was no shut down on this decoder. If your way works, though, I'll be Happy!
 
Don't make a decision to buy a sound decoder if you've only heard just one. Best advice for all here is to listen to as many as possible before buying ANY sound decoder. Have the good fortune to know a LHS who sells sound systems. Have also heard them at many MR shows. Last year he had demos by LokSound, Soundtraxx & TCS. Everyone agreed LokSound was the best because of their sound quality & many additional sound features.
 
The way the startup and shutdown of that decoder is supposed to work, is it starts when you dial up the address, and shuts down when you deselect the address.
There is a CV setting to enable/disable this.
 
The way the startup and shutdown of that decoder is supposed to work, is it starts when you dial up the address, and shuts down when you deselect the address.
There is a CV setting to enable/disable this.

One would think that, wouldn't one? CV11 at default is set to 00 which Should shut down the sound when deselected and setting it to 06 will keep the sound going. This is when using a DCC system that is not the Digitrax DCC system. HOWEVER, this is not true with all systems. I am running the MRC Prodigy system and the going theory is that it never really deselects a loco once it has found it on the system. The control unit always sees the loco so it just keeps it running. I've tried it both ways with no difference. That's okay; I have a passing siding that I can switch the power off to that I can park it on should I feel the need to shut it down.

josephbw said:
If I remember right, you double tap F9 3 separate times to enter each stage of shut down. The final stage is the doors closing. Then to start it back up you double tap F6.

Yeah, tried it. Didn't work. F9 is brake squeal. That's all it does.

cajon said:
Don't make a decision to buy a sound decoder if you've only heard just one.
Also good advise.

But, like I said, I'm cheap and the whole smash was only 45 bucks! I really don't feel that I have wasted my money at all. AND, should I feel the need to upgrade in the future, swapping out a speaker or a decoder is a fairly straight forward job. I know that I bought the econo-line of sound decoders; I wasn't expecting a Cadillac.
 
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$45 is only about $25 more than a silent Divitrax decoder, so you're not out much if you end up not liking the sound. And you can always disconnect the speaker and make it a silent decoder.
 
this decoder superceded their earlier decoder with improvements. Since I have multiple engines and computers, the decoder makes sense for some specialized projects and you can create and modify as you need. If you have the mad skilz, these decoders have no limits. I installed one in a North Shore interurban with the trolley project, works great.
 
Nice review. That is one model I do not have in my collection. I think I have exactly 1 Digitrax brand sound bug somewhere, but that is it.

It is certainly not a Bose Quality speaker...
Well, since physics don't scale, there is physically no way to get that sort of quality out of a speaker that is going to fit into an HO scale model.

I spent about 7 years trying using the Bose theory design model (BTW I consider Bose to be the Jaja Binks of the "high quality" speaker market). I came up with several variations with dual, triple, and quad cones, crossovers, facing and rear firing speakers. One totally filled an Alco PB shell, I must have missed a calculation in my harmonics on that one though because it was pretty doggy. But this contraption below (which incidentally is not a Bose type) is as close as I got. The heavy plastic curved walls prevent external vibrations (and associated counter harmonics), it has a chamber volume tuned with the speaker size and throw, and interior dampening. It consumes a Stewart brand F3 shell. Even with hours of calculations, careful measurements, and high quality electronics it, as I said above, it is as close as I got to Bose and still, at that, not even close.
unassembled%20speakers.JPG

assembled%20speaker%20small.JPG

StewartSound.JPG
 
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Wow, a 7, almost 8 year old thread of mine! Nice! :)

That little SDH166 set up came to be considered one of poorest decoders for sound quality before I made the switch to RailPro. It always ran great in the Bluebox Athearn I had installed it in, though. Running quality - No Complaints! Sound quality - meh... I discovered that a big part of that was the speaker. I tried a few different ways of setting that up, but it paled in comparison to the iPhone 4 speakers that are in most of my locos now.
I'm still running that Digitrax speaker though... 'cause... you know... I'm still cheap. 🤣
 
I do not have a lot of money either, so sometimes I have to get what I can afford. Sadly the guy that was supposed to show me how to install he was a no show, he said he slept in….wasted an hour drive.
Only saw this today, didn't know he was a no show, very disappointing when that happens.
 
Only saw this today, didn't know he was a no show, very disappointing when that happens.
Luckily, another guy from our club walked me through the process and he was awesome! The engine worked beautifully! I was running it on my layout again last night but my unsupported well enough track was causing it to derail the guidewheels and centipede type tender every time around the layout.
 
Luckily, another guy from our club walked me through the process and he was awesome! The engine worked beautifully! I was running it on my layout again last night but my unsupported well enough track was causing it to derail the guidewheels and centipede type tender every time around the layout.
If the tracks unsupported that will happen as the track will dip and twist, being HO, the wheel flanges aren't very deep so the wheels will climb out the track.
I would avoid that section till you get that sorted or you could end up with the loco taking a nose dive to the floor.
Glad it's up and running, now how many more do you need to do? :D
 




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