Getting sound out of a tender

[Maletrain]

I am thinking about how to get good sound out of an N scale tender.  In the Bachmann all-wheel-pick-up tenders that were not designed for a speaker, it looks hard to get the speaker under the circuit board to let the sound out the bottom through a speaker-sized hole.  I know that people often mount the speaker under the coal load and then drill holes through the load.  Maybe it is the great macro photography used to illustrate those holes, but they seem to be noticeable to me.

So, I am wondering about trying the following: remove the plastic coal load, replace it with a screen cut to fit and formed to approximate contour, spray the screen with glue and sprinkle on scale coal.  Repeat applications of spray glue and scale coal until the screen is covered by a porous layer of scale coal.

I would look better, and, I think maybe allow sound to pass through better as well.

Comments and suggestions welcome.

[JMaurer1]

I'm thinking of leaving a small gap around the edge of the coal load (between the sides of the tender). Any view except from possibly above would make the gap almost invisible...

[Ed Kapuscinski]

You should definitely grab a copy of the 2016 NTRAK Steam Annual when it comes out. There's an excellent article in there from our own @jdcolombo about sound techniques.

[jdcolombo]

You really should get the NTRAK steam annual 

But here's a preview.  I  always mount my speaker below the coal load, firing up at the load.  You don't need to take the coal load out.  Instead, take a #76 or smaller drill bit and drill a bunch (30 or so) of holes in the load at an angle to the load.  Once the speaker is in, these holes will be invisible in anything but macro-close-up photography.  And you might not need any holes at all - most tender shells leak so much air that the sound will get out of the shell just fine IF you follow the next paragraph.

The key to decent sound is not where you place the speaker (firing up or down), but putting the speaker in its own sealed enclosure.  If you want the best sound, DO NOT RELY ON THE TENDER SHELL AS A SPEAKER BAFFLE.  Period. 

And if you buy the 2016 NTRAK Steam annual, I'll tell you how to do all this, including building a speaker enclosure, in detail with pictures!

John C.

PS - here's a teaser photo of a speaker mounted in a Bachmann 2-8-0 tender shell:

[Mike C]

My first sound install I cut out the coal doors . But I've since realised that I don't need any sound holes in the tender . I've sent a few steamers to woodone for sound , and the last few have have no holes in the tender . They all sound great and the volume is just fine , I usually turn them down .  Also the BLI M1's have no sound holes and their volume is way too loud from the factory .

[Maletrain]

Thanks for the preview John.  And I will definitely be getting the Steam Annual.

[peteski]

John C's post reminded me of a several-years-old unfinished project: Model Power 4-4-0 loco.  When Digitrax came out with their first small sound decoder I set out to install it in the tender of that loco.  I dug  the tender out of the pile of unfinished projects and took some photos. Like John mentioned, I drilled lots of very small holes in the coal load.   While it is true that a speaker in its own airtight enclosure will be audible without any holes drilled in the shell, to me it is not all about the sound volume. My opinion is that the sound quality (not just volume) is better, especially the higher frequencies when the speaker is directly exposed to the ambient air (holes in the enclosure). But this is my subjective opinion. However, if that was not true then why do all the commercially-made devices which have speakers have openings (or mesh) exposing the speaker to the outside of the enclosure. 

Here is a closeup photo. Those holes are not easily noticed when viewed with a naked eye.

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[Cajonpassfan]

You really should get the NTRAK steam annual 

The key to decent sound is not where you place the speaker (firing up or down), but putting the speaker in its own sealed enclosure.  If you want the best sound, DO NOT RELY ON THE TENDER SHELL AS A SPEAKER BAFFLE.  Period. 

And if you buy the 2016 NTRAK Steam annual, I'll tell you how to do all this, including building a speaker enclosure, in detail with pictures!

John C.

PS - here's a teaser photo of a speaker mounted in a Bachmann 2-8-0 tender shell:

Agree with John wholeheartedly about the enclosures. He is the sound guru! As to speaker orientation, I prefer to point mine forward where there is room but even if there isn't, I open up the front part of the tender (since my steam is all oil burners, I can't drill holes through the coal). This has the added benefit of throwing the sound forward, towards the locomotive, and diminishing as the loco passes.
Otto K.

[Mike Madonna]

Otto, good point about "oil" tenders!

In my Southern Pacific ACs and GS-4, I did NOT need to modify the tender at all. There is enough of an "air gap" between the floor (chassis) and shell to allow the sound out. In both cases, the speaker is "firing" (or facing) up towards the top of the tender shell. As John C. will agree, an air tight enclosure is a MUST!

[wm3798]

When I did a sound conversion using a tender speaker, I cut the plastic coal load out altogether, and replaced it with an open cell foam rubber bit that I finished with some black sand or coal shavings.  The results were reasonably good looking, and allowed the sound to get out of the box...  The material I used is similar to the covers one might find on a big stereo speaker, for those of you remember that sort of thing.



In this shot, 761 has the sound baffle coal load, and 763 has the factory plastic one.

And a little video to show the results...

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For an oil bunker, I think it could easily be done by cutting some openings at the front of the bunker behind the cab where they wouldn't be obvious during normal viewing, or if there's a running board across the top of the tank, leave that open and use a brass etching to cover it.

Lee

[mmagliaro]

...
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 While it is true that a speaker in its own airtight enclosure will be audible without any holes drilled in the shell, to me it is not all about the sound volume. My opinion is that the sound quality (not just volume) is better, especially the higher frequencies when the speaker is directly exposed to the ambient air (holes in the enclosure). But this is my subjective opinion.
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Most of the people in Railwire are probably old enough that we can't hear any high frequencies above 4 KHz anyway!       
And some of us played in rock and roll bands when we were younger, which makes the problem even worse.
       (Yes... DOUBLE troll)

You are correct, of course.  Put a baffle directly in front of a speaker, and the treble frequencies are the first thing to go.
And it isn't easy to compensate for that because not all treble frequencies get rolled off and they don't get rolled off uniformly,  so you can't just "turn up the treble" and expect to get the same tone you would get with some holes in there.