Thoughts on the Atlas S-2/ESU Loksound and a speaker transplant

jdcolombo Aug 3, 2015

  1. jdcolombo

    jdcolombo TrainBoard Member

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    Hi folks.

    I finally got my sound-equipped S-2, and took it apart to take a look at the sound installation.

    The sound decoder board inside the unit is 8.25mm wide, and runs the entire length of the engine from the front of the hood to the cab (about 50mm). However, the active components on the board span only about 40mm - the rest of the length is simply to fit the board to the mounting tabs inside the locomotive. The components are on both sides of the board; the bottom has a number of caps soldered to the front end, some of which may be rectifier caps but some of which are likely keep alive caps (I had literally no sound dropouts on my unit, which is an EL from the latest delivery; I did clean the wheels before putting it on the track). This leads me to believe that ESU could fairly easily produce a generic board that would fit nearly any hood diesel - you just lop off the extra length (which also contains SMD LED's), and you have a board that is 8.25mm wide by 40mm long, which would fit in nearly any kind of hood diesel including things like the VO-1000, and maybe even an SW switcher. It would need to be hard-wired (the decoder in the S-2 is all hardwired from the trucks and to the motor) but that's a tradeoff I'd take in a heartbeat. Let's hope the folks in Germany will go down this route once they have fully supplied Atlas (and I assume Intermountain) with these boards.

    The speaker is not a flat cell-phone type speaker, but rather a flat-ish 15mm round that is installed in the molded inner cab detail section and faces the rear of the unit. The sound is pretty good - not quite as good, I think, as the Rapdio GMD-1, and not as good as what I've gotten out of my custom installs, but pretty darn good. The "duck" horn is particularly effective, as is the bell. The irregular "heartbeat" and turbo sound of the ALCO 539T prime-mover is captured wonderfully; the only real problem is that there is no bass or even what one might call low midrange to even suggest bass, but what's there is well-done.

    Not being entirely satisfied, I decided to replace the stock speaker with an 8 x 12mm "sugar cube"-type in a custom enclosure I built from .020 styrene. The replacement is a really simple operation. Remove the hood and cab by unscrewing the two screws on the underside of the engine just in front of the front truck and lifting it off (you'll have to rock the cab a bit to free it, and don't forget to remove the rear diagonal handrails that attach to the cab before doing this). Now remove the plastic cab insert by pulling straight up on it. The round speaker is inside. Desolder it from the board, place the new speaker in the vacated space firing toward the hood, solder it back to the board, and put the hood/cab back on. Done. Here's a photo of the transplant (the original stock round speaker is in the foreground:

    [​IMG]

    The replacement speaker is considerably better than the factory one - louder, and more low midrange which gives at least a hint of "body" to the prime mover. Not counting the time spent making the speaker enclosure, this was a 10-minute job.

    As for operation, it is excellent, although Atlas decided to invert the normal sound on/sound off sequence for ESU decoders. Normally, an ESU decoder is silent when powered up; you press F8 to turn the sound on. The S-2, however, is just the opposite: sound is on at power-up, and you have to press F8 to turn it off. This behavior can be changed in the CV's if you want - I prefer ESU's default of "silent until F8 is pressed" but to each his own. I suspect Atlas set things up this way so that they wouldn't get people calling them saying "Where's the sound?" because they didn't know to press F8 (heaven forbid we should read instructions; after all, this is still a male-dominated hobby . . . ). The engine also comes with the default start-up delay, where the engine doesn't move initially when you open the throttle; instead, it waits to "throttle up" the prime mover, and then begins to move. This is about a 3-second delay, and could be annoying to some folks (and you can disable it by changing a CV).

    The rest of the engine is just amazing. The handrails are so thin I'm afraid to touch them; the unit itself runs very smoothly and pulls 15 of my NRMA-weighted box cars easily on flat terrain. They would be perfect for yard duty or switching a steel mill or other heavy industry. I hope Atlas sells a million of them, since that means I'll one day get one in NKP paint!

    John C.
     
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  2. hoyden

    hoyden TrainBoard Supporter

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    John,

    Thanks for your research. I noticed the S2 runs very well with almost no dropouts. The extra capacitors would go a long way to explain the performance. Compared to my BLI E8's and PA's the S2 has very diminished sound volume. I'm encourage to know a replacement speaker can help.

    Do you have a Digikey part number for the speaker?
     
  3. jdcolombo

    jdcolombo TrainBoard Member

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    Digikey doesn't sell the 8 x 12mm speakers (I bought 50 of them when they were still available as an OEM item from a different electronics supplier). Instead, you'll have to get an 8 x 12mm "sugar cube" speaker from one of the on-line DCC suppliers (if you PM me, I can suggest one). These usually come with an enclosure either already attached to the speaker or separate that you can attach yourself, and usually are oriented so that the speaker solder terminals are on the top (e.g., the speaker is firing down into the enclosure, which works fine, because you hear the back wave out the back). In this case, though, I think a custom enclosure is better, because the way the speaker has to be oriented, if the solder terminals are exposed, they will hit the frame and cause a short. Using a custom enclosure puts the speaker terminals inside the enclosure where nothing can short against the frame.

    John C.
     
  4. hoyden

    hoyden TrainBoard Supporter

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    Digikey has a Knowles 12 x 8 mm, 32 ohm speaker. that looks like it could fit.
     
  5. jdcolombo

    jdcolombo TrainBoard Member

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    Note that the 32-ohm Petra is meant as a near-field speaker/receiver (e.g., for a cell phone held up to your ear). The spec sheet shows that it's average measured SPL is 85db at 1 meter at 1 watt. That compares to 98db for the Wildcat (9 x 16mm) or the Donau (11 x 15mm), both 8-ohm speakers. A 10db increase is subjectively double the loudness. So 13db difference between the speakers means that the 8-ohm speaker will be perceived as more than twice as loud as the 32-ohm. If you have a quiet layout room and like your sound levels relatively modest, then the Petra might be OK. The only real way to tell is to try one and see how it works for you. Actually, this is an experiment I might try myself.

    John C.
     
  6. hoyden

    hoyden TrainBoard Supporter

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    John,

    I understand the power business and the value of an 8 ohm speaker. My room is quiet but I have a bit of hearing loss so volume is good. I appreciate any pointers to sources of speakers you have to recommend.
     
  7. DougSluder

    DougSluder TrainBoard Member

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  8. hoyden

    hoyden TrainBoard Supporter

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    Is there any special trick to getting the cab loose? After removing the screws at the front I could raise the hood. However the cab is firmly affixed to the frame. I tried rocking it back and forth side to side with considerable force but the cab won't budge. It's like there is glue or another screw holding it on. I tried both locomotives and neither will budge.

    It's scary to apply as much force as I have for fear that something will snap that isn't suppose to snap.
     
  9. jdcolombo

    jdcolombo TrainBoard Member

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    Nope, there's nothing holding it on except a lot of friction. On mine, the engineer side of the cab (with the long hood facing forward) came up slightly with rocking; the fireman side wouldn't budge until I got a small, very sharp screwdriver, inserted it between the cab and lower walkway, and twisted slightly. Once I freed it up a bit, I rocked it the rest of the way off.

    John C.
     
  10. cajon

    cajon TrainBoard Member

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    Nobody has mentioned RailMaster Hobbies speakers. They are the best sounding speakers out there having heard several at MR shows & at a friends home layout. Check them out here:
    http://railmasterhobbies.com/Speakers.htm
     
  11. hoyden

    hoyden TrainBoard Supporter

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    John, I will try the screwdriver. I did get one side slightly raised almost enough to get something in there to wedge it apart. Maybe with a little more wiggling I can get the slot a little wider. It's definitely a tight fit.
     
  12. jdcolombo

    jdcolombo TrainBoard Member

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    Well, the speakers listed on this page are all way too big for N scale diesels. Maybe some of the smaller ones would fit in a large tender . . .

    John C.
     
  13. Seltech-USA

    Seltech-USA New Member

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    If any support is needed for the Knowles cell phone speakers, then Seltech would be glad to help.
    www.seltech-international.com
    We are a global distributor of small speakers.
     
  14. jdcolombo

    jdcolombo TrainBoard Member

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    Wow - a reply from the manufacturer! I hope you have an appreciation for how much the Knowles speakers are being used in model railroading. I know we're a VERY small market compared to cell phones, but the discovery of the Knowles speakers has been revolutionary for model sound installations, particularly in N scale.

    Now if I can push my luck: would you consider manufacturing an 8-ohm, 8mm x 12mm speaker? The 9mm x 16mm Wildcat will fit in N scale hood diesel installations, but there are some situations (like the Atlas S-2 switcher that is the subject of this thread) where an 8 x 12mm is really the only thing that will work. Star Micronics used to produce an 8-ohm 8 x 12mm speaker, but those have disappeared. Again, I realize this is a request from a very small market, but I don't know how hard it is to turn something like the Petra from a near-field 32-ohm to a standard 8-ohm with the accompanying higher SPL output.

    And in any event, thanks for replying here. And if you'd like to see what else the modeling community has accomplished with Knowles speakers, visit my YouTube channel here:

    https://www.youtube.com/channel/UCryHlnCSg_HXMoRcEupZWZw

    John C.
     
  15. Seltech-USA

    Seltech-USA New Member

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    Seltech is a value-added distributor for Knowles. There was formerly the 8x12mm, 8 ohm TINY speaker (p/n 2403-260-00029), which was discontinued a few years ago. Some may still be available in excess inventory. It's an interesting size, so if it is produced again, I can let the group know. We still have inventory of the 13x18mm DUMBO speaker, which became popular among hobbyists a few years ago.
     
  16. jdcolombo

    jdcolombo TrainBoard Member

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    Ah - my bad. For some reason I thought Seltech was the parent company of Knowles. Yes the 13 x 18mm size is very popular in HO scale, where there is more room in the engines, and I've used a number of Dumbo speakers in N-scale steam locomotive tenders. But perhaps you could pass along to the folks at Knowles that there is this hobbyist market that would REALLY value an 8 x 12mm. Again, I realize it's a long shot and that we're a tiny market in comparison to, say, Samsung or Apple, but if you never ask . . .

    John C.
     
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  17. Seltech-USA

    Seltech-USA New Member

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    I would recommend to check if Streamlined Backshop has any of the Knowles 8x12mm speakers available.
     
  18. esfeld

    esfeld TrainBoard Member

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    John ...... or anybody ......... what CV did you use to have the S2 start Muted? .... I too prefer this.
     
  19. jdcolombo

    jdcolombo TrainBoard Member

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    From the LokSound Select FAQ (http://www.esu.eu/en/support/faq/loksound/loksound-select/):

    PLEASE NOTE:

    Some Manufacturers have had our decoders factory equipped in their locomotives and have opted to have the sound ON as a default. If you have a locomotive with these settings and prefer our standard settings above you will need to set index CV 32 to value of 2 then set CV 403 to a Value of 16. After this Change CV32 to a value 0 then change CV 13 to 128.

    John C.
     
  20. esfeld

    esfeld TrainBoard Member

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    John
    Thank you .... I got that originally from the ESU site .... I changed those CVs accordingly to no avail ... I thought perhaps you had additional amplifying info. I interpreted their info using CV32 to 2 and CV 403 to 16 as being for DCC and the additional (CV32 to 0 and CV13 to 128) as being for DC ...... as I see no purpose in changing CV 32 twice. Am I wrong? This confusion is what led to my request for additional info from someone who has successfully done this. Any additional info would be greatly appreciated.
     

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