Sound and Sugar-cube Speakers

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beiland

Well-Known Member
This was just recently posted on a soundtraxx discussion I had started about the incompatibilities that could arise when running MTH locos with other DCC equipped locos. I found this 'sounds portion' very interesting,...

>What size sugar cube speaker to install in smokebox?<

My pragmatic response to this query would be “the largest that can be fitted”.

I have now placed a lot of these small speakers (with enclosures) in the smoke boxes of my varied brass locomotives, and each install is different. I do favor the 13x, and 11x sugar cubes if they will fit, but have also gone down to 9x and 8x (both in pairs). They all seem to work well, and sound great- enough different from each other to make it interesting. I use the 3D enclosures from Streamlined Backshop, each of which has enough meat so that one can quite effectively sand, file, or even -with care- a saw to thin and shape the sides to fit.

I have detected no auditory advantage (to my ears, anyway) with dual speakers, except when desired volume with quality sound cannot be obtained in any other way (such as with the small 8x speakers).

Generally, I have firmly moved to never, ever again put speakers in tenders, and I already have removed tender speakers in some in favor of smokebox sugar cubes, or sugar cubes in boiler, fire box, or form fitted under cab roof. What tremendous improvements! The SP cab forwards are an exception, where the the smokebox is separated from the tender by only an apron. Even so, I would bet that two fine sugar cubes alone in the smokebox would do the trick (I have a brass Winton 2-6-6-6 Allegheny with two 13x sugar cubes in the fire box that simply sounds as this gigantic locomotive should sound..

A truly successful recent install was in a KTM LS&MS 4-6-0 (1964). This graceful lank locomotive simply did not have enough room for decoder (Tsu 2 Micro) and speaker of adequate size- without compromising fundamental operating requirements. I installed the decoder in the tender, and a 11x sugar cube facing down in the boiler space above the driveline. The results are spectacular (i.e. spectacular). Tender and locomotive are connected with TCS micro connectors (a six and a two), and wires effectively disguised with a generous application by a black Sharpie pen.

Denny S. Anspach MD
Sacramento CA
 

KB02

Well-Known Member
I wonder what his specific reasoning is for not wanting sound in the tender? Other then Moving the sound a few (real) inches forward.

I put a sound decoder in my 4-6-4 Hudson and it sounds FANTASTIC (even with an MRC decoder and speaker).

The first loco I put sound in, I just used a regular speaker box inside the shell. Sounds ok... just ok. Then I watched this video and my next two installs were 1000 times better:
https://www.youtube.com/watch?v=j4kgLeDltxg
 

tootnkumin

Well-Known Member
Staff member
I notice those in the club who run steam, even with HO, the sound seems unrealistic when the speaker is in the tender, especially with the longer locos. One member added a small, additional speaker in the smoke box that enhanced the chuff and sharper steam sounds markedly. Put the sounds in the place they are supposed to be.
 

beiland

Well-Known Member
I notice those in the club who run steam, even with HO, the sound seems unrealistic when the speaker is in the tender, especially with the longer locos. One member added a small, additional speaker in the smoke box that enhanced the chuff and sharper steam sounds markedly. Put the sounds in the place they are supposed to be.

Back a number of years ago I was doing a lot of reading (and some posting) of this sound subject (and yes KB02 I remember that video well). At that time there was very little (almost none) of the cell phone speakers being utilized. We were looking for spaces where conventional speakers could be placed, and in the loco shell itself,... that offered almost no possibilities.....so the tender installation became the place.

Then it became a study of how to envelop those speakers to the best effect,...very much akin to the old tech of stereo h-fi home speakers. But the sound was still emanating from the tender, not the loco itself. I recall seeing one experiment done by a friend of mine where he placed the speakers in the tender, BUT had them facing out a relief in the front of the tender, blasting into the fireman's cabin on the loco. It was very surprising the effect !!

I'll see if I can find any of those references.

Meanwhile what really surprises me about the cell phone speaker success is that I was always a believer that sound was better produced by being able to move 'quantities' of air, thus larger speakers. Doesn't seem to be necessarily so with this sugar-cube speaker technology.
 
Last edited by a moderator:

beiland

Well-Known Member
a Few of those 'sound' links

http://www.modelrailroadforums.com/forum/showthread.php?15747-C-amp-O-Allegeheny-Sound

Designing Locomotive Acoustics for On-Board Sound Systems
http://www.modelrailroadforums.com/forum/showthread.php?11521-Designing-Locomotive-Acoustics-for-On-Board-Sound-Systems

Ah ha, here is that posting I made about the 'front facing speaker installation,..
As I re-read this PDF document several times I became aware of a possible speaker installation that was not covered in this document....excerpt:

"Separate back wave from front wave: It is important for sound quality that the inside cab area be sealed as much as possible to prevent the back wave from escaping through grills, vents, fans or other openings in the diesel or electric locomotive cab or through the openings in the chassis where the motors connect to the trucks. If there is any leakage of the back-wave to the outside, it will mix with the speaker front-wave and cause destructive inference in some base tones and perhaps constructive interference for some of the higher frequency tones. The respective path lengths for the front-wave and the escaping back-wave and the position of the listener will determine which frequency components are degraded or changed. Usually, since the acoustic chamber and path lengths are short, any back wave escaping from the locomotive causes degradation of the sound. If the back wave is allowed to escape close to the front-wave, the degradation is more severe. As the scale of the model decreases, this becomes more of a problem since the distances between front and back waves become smaller.

Vent the front-wave sound under the locomotive: Propagating sound upward into the open air seems to produce lower quality sound unless you are directly over the speaker. The sound has no opportunity to reflect against different parts of the layout such as buildings, mountains, etc. that add both volume and presence. Our experience is that the best design choice is to propagate the sound under the locomotive. The next best choice is out the sides of the locomotive through vents and grills. If sound is vented under the locomotive, always be aware of the affect of trucks and other obstacles and other factors that can either improve or degrade sound quality. Do not vent sound straight down too close to the track where it can be reflected back and decrease volume and sound quality. Venting the sound directly under the fuel tank usually does not produce good sound in smaller gauges (HO and N) since there is little space between the bottom of the fuel tank where the sound is vented, and the top of the track. Sound usually reflects back from the track resulting in poor volume and presence. Venting through the gear tower and chassis over the open truck areas seems to produce the best sound."


What I find interesting here is no mention of venting the 'front-wave' from the front of the tender, verses out the bottom, or out the coal load?? Why does this interest me? I have at least 4 locos with vandy tenders (C&O) that I wish to install sound into. He covers vandy tenders to some considerable degree, but does not mention this possibility.

I happen to have a friend who has a relatively cheap little IHC steamer that has its sound vented out the front bulkhead of the tender right into the cab area of the loco....the sound is GREAT. On the other hand I have a 2-8-8-2 with the sound vented out the coal load that I consider substandard. So I am giving real serious consideration to experimenting with one of my Spectrum C&O Heavy Mountains with their vandy tenders and venting the sound forward out of the tender.

Has anyone else seen such an installation? Does anyone have a photo and/or illustration of the 'factory sound' installation in these Spectrum models??


Some sugar-cube references over of that other subject thread,
[url]http://www.modelrailroadforums.com/forum/showthread.php?11521-Designing-Locomotive-Acoustics-for-On-Board-Sound-Systems&p=409417#post409417[/URL]
 

Iron Horseman

Well-Known Member
I wonder what his specific reasoning is for not wanting sound in the tender? Other then Moving the sound a few (real) inches forward.
That would be the winner. Reguardless of the quality of sound, when one is close to the locomotive it is easy to tell the sound is not coming from the correct location, and just seems wonkey.
 

bnsf971

Gomez Addams
Staff member
When I'm five feet away from the engine, the sound being in the tender isn't quite so dramatic as when I'm a few inches away.
It's especially noticeable when I shoot video up-close, and the engine passes the camera. The sound coming from the tender is very obvious.
 




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