Advice on sound for steam locomotives

[Mike Madonna]

Peteski,

Here are the specs on the CT Elektronik "Sugar Cube" speaker:

15mm L x 11mm W x 9mm H*
8 ohm
1-2 Watts
Sound Chamber Included

* = 9mm high with sound chamber installed

The sound chamber is included, but NOT attached to the speaker. I have installed these in two IM AC-12s. With the Loksound Select Micro, I chose to lower the "main" volume from 70% (of max) to 60%. I did this for two reasons; one, the volume was a bit loud for an N scale loco. Second, when I put two on the same track, they were very loud. Now, they sound a bit closer to "scale". While the two are like "music to my ears", the lower volume is more realistic, IMHO.

Hope this helps....

Mike

[Bart1701]

OK - I am ready to start the install of my sound decoder in the tender of my Bachmann 2-8-0 Consolidation. I am using the Soundtraxx TSU-750 and their 810112 Oval Speaker. I also purchased 2 of the Tantalum capacitors from DigiKey. Before I get started, I wanted to confirm that my wiring diagram is correct and ask a few questions.

1) How do you tell which end of the tantalum capacitor is Positive and Negative. In looking at them, I see that the contact on one end has a small u-shaped notch cut out of it. What polarity is the end that has the notch cut out of the contact?

2) For the speaker enclosure, I was going to build a speaker box out of plastic. Does the thickness of the plastic matter? If so, what is the recommended thickness to use?

3) What's the best way to secure the speaker on/in the enclosure? Can it go right on top, or is it better to recess it so that the top of the speaker is flush with the top of the enclosure?

4) Seal all edges/gaps in the speaker enclosure? The seams, where the wires enter the enclosure, etc.?



Many thanks!
Bart

[jdcolombo]

Hi Bart.

1.  The tantalum chip caps usually have a stripe at one end.  This is normally the Cathode (+) end, but the best way to make sure is to look up the data sheet for your cap (the sheets are linked at DigiKey; type in the part number and you should find links for the data sheet).  The data sheet will tell you if the strip end is Cathode or Anode.  Since there isn't a "standard" for tantalum chip caps, your safest bet is to check the data sheet.  Also, you want to make sure you wire the caps in PARALLEL, not in series.  The diagram you have drawn shows them wired in series.  Easiest way to do parallel wiring is simply solder the chip caps to each other back-to-back, with the two positives soldered together and the two negatives soldered together.  Then the blue wire goes to the positive end.

2.  Thicker is better.  You want the enclosure to be as stiff and non-resonant as humanly possible for the space.  Use the largest thickness you can.

3.  Recess the speaker so that the edge of the enclosure is flush with the top of the speaker.

4.  Seal everything.  Silicone sealant and gap-filling CA cement are your friends in this endeavor.  You want a completely air-tight box when you are done - and don't forget to seal up the speaker mounting holes (if there are any).  It's easy to overlook this.

Good luck, and let us know how it goes.

John C.

[Bart1701]

All finished! 

I successfully installed ( or "crammed" may be a better choice of words ) a TSU-750 sound decoder, speaker and two tantalum capacitors into the tender of my Bachmann 2-8-0 Consolidation. My tender was apparently one of the early versions, where the sides of the tender are attached to the frame, and the top of the tender is part of an rectangular insert that fits into the tender walls. That means you have just slightly less room to work with than the tender that John C. was using as shown earlier in this post.

Here is a short video of the engine in action:

The exhaust chuffs are not perfectly synchronized at 4 chuffs per wheel rotation; I just set it to a rate that sounded good to my ears.

Thanks,
Bart

[jdcolombo]

Hi Bart.

Excellent sound.  You did a great job on this.

Yes, the early tenders don't have as much room; glad you found a way to shoehorn all this in.  On the upside, the early tenders are more air-tight and have stiffer shells, which helps with the sound, and yours sounds excellent.

I'd probably increase the setting of CV116 to get the chuffs a bit more in line with driver rotation, but it's your engine - do what seems right to you!

John C.

PS - I'm seriously considering tackling some sound in my diesels.  While the drone of the prime mover isn't all that appealing to me, the bell and horn are a big deal at crossings, in yards, doing switching moves and so forth.  The problem for me is the narrow width of the GP7's, 9's, RS3's and RS11's that were prevalent on the NKP in 1957; need to find a suitable speaker, probably an oval with a maximum 11mm width.  Got some leads, but if anyone out there has suggestions, let me know.

John C.