Hello everyone,
I need a bit of help to complete installation of a TSU 1000. I have installed the decoder successfully (the engine moves as it should). But I'm a little stuck on installing the speaker.
I purchased a 1" speaker which fits into the tender, just below the coal load (the only spot big enough). I would like to drill holes in the tender coal for sound to come out there. Although the engine was DCC ready, there is no place for a speaker on the bottom of the tender. I see the wires to attach from the decoder to the speaker. My question is about the enclosure.
I purchased a 1" enclosure to go with the 1" speaker. The enclosure has three parts; two plastic rings, each about 3/8" deep, that snap together and a plastic disk which also snaps into the two rings. I have no idea where to place the speaker. Is it between the rings? Is it at one end with the round disk at the other end? Is the disk necessary? I've read that some people don't use an enclosure and use the tender as the enclosure. Does this work well?
I've also read that sound comes out of speaker from the back (magnet side) and not the cone side. Does this mean I should have the magnet side facing up to get sound out through the holes in the tender coal? I thought it would the other way round.
Confused
To use an enclosure, the speaker goes in one end, and the rings go next, and the disk seals the other end.
Sound comes out both sides of a speaker, which is the reason for an enclosure - the back side is 180 degrees out of phase (when the front is pushing out, the back is pulling in and vice-versa) so if those two sound waves interact, they cancel each other out. If they perfectly interacted, you'd get nothing but silence. Since they don;t, you hear sounds, but not at a great volume, if you just have the speaker sitting there.
If you tender is reasonably tight fitting, then the tender shell can act as an enclosure, if the speaker is sealed to the surface so the sound from the back side cannot escape the same place as the front side. Tenders aren't usually air tight though so an enclosure may still be the best bet. You can try without - if the tender is sufficiently closed up, it will work with maybe a little less volume then a true enclosure.
There is some school of thought that says place the speaker int he enclosure with the magnet out - for a typical round speaker the main reason for this would be to increase the volume in the enclosure, since the magnet and frame of the speaker won;t be taking up space in the enclosure. But it will work just fine with the face out - the key is the enclosure must be air tight, and that includes any hole you need to make for the speaker wires. Plug that up with some caulk.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
I'm not familiar with youe enclosure assembly but can offer a few other comments.
The only place I've seen comments on the magnet (vs diaphragm/cone) facing outward is on the flat, rectangular sugarcube speakers. I believe that Streamline Backstreet Shops recommends that, and Tony's Trains now offers them and advises that, I believe noting that distortion was measured some 2/3 less that way.
I'd guess you have a choice of putting your speaker facing out the coal load (and drilling holes for the sound) or drilling holes in the tender bottom and facing it out the bottom, if it can fit there. There are some older threads on Bachmann tender installs for both approaches. I did a couple of Bachmann 2-8-0s, both more recent than the Spectrums, and the floor on the tender was set up for an outward facing speaker there. I used 1.1" speakers with square enclosures so had to mill the round speaker spot to mount the square speaker, facing downward.
However installed, the speaker wants an enclosure for best performance. This means the outward facing side needs to be isolated from the rear side somehow. For the sugarcubes, it's essential or gross distortion occurs as the back side interacts with the front. For other types, it's still important for lesser distortion and also enabling good air movement (output) from the front. The front isolation can occur more than one way. If in an enclosure, that does the trick. If facing out and not in a speaker enclosure of it's own, one would want the front isolated from the rest of the tender interior, to prevent interaction at the least. If the tender box was well sealed behind the front of the cone, it would provide a nice enclosure from an output standpoint as well as preventing the distortion mentioned. I think often folks may have imperfect enclosures for the speaker back but still get reasonable sound, but best would be obtained with a sealed enclosure. What I read usually says a bigger enclosure is best, but I've used some teeny enclosures with the sugarcubes in some tight diesel installs and had decent results.
Paul
Modeling HO with a transition era UP bent
Put the speaker in the enclosure, make sure it is sealer air tight and mount it in the tender where ever it will fit comfortably and try it as is. You might well find you won't need additional holes in the tender to let the "sound get out".
The sound will reverberate within the tender shell giving less direction as to where the sound is coming from - which can help with the illusion as the sound doesn't come from the tender in a real steam engine !
As soon as you provide holes for the sound to escape, that location immediately becomes a focal point for where the sound is originating from. Without those "escape holes", it's not as obvious where the sound is coming from.
Mark.
¡ uʍop ǝpısdn sı ǝɹnʇɐuƃıs ʎɯ 'dlǝɥ
A couple of more notes.
You don't need to use both rings. Use just one if you're cramped for space. You could even leave the end off, provided the ring is bonded to a flat metal surface that won't leave room for sound to escape. Use both rings if possible, because the extra volume generally helps (although how much extra depends on a lot of things, so just to keep it simple here, think about what fits or doesn't).
If directionality of the sound is important to you, the best install would be a speaker in the smokebox, but that can be tricky. Well worth it if there's space and you do it with a good enclosure.
Mike Lehman
Urbana, IL
Thanks everyone. Got the speaker installed and it works great!
No Longer Confused (for a while)
Don - Specializing in layout DC->DCC conversions
Modeling C&O transition era and steel industries There's Nothing Like Big Steam!
Don,
Thanks for the continued followup. I did install the speaker under the coal load and then sealed the holes and gaps at the bottom of the coal load box. I have not drilled holes in the coal load to allow the sound to come out there so I guess its just coming through the plastic of the tender.
I have made no adjustments to the decoder - not even changing its engine number - I'm running as 03. I like the chuff sound. But what I'm not certain about is a whine that starts up when I apply power to the engine. It starts at a high pitch and then drops but does not seem to disappear completely. All other steamer sounds are there. I don't run diesels but I would almost say it sounds more like a diesel might sound starting up. I think I have the right decoder because of the steamer sounds. I don't have this whine on any other my steamers. Is this the motor trying to cope with a voltage that is too high? I assume the motor could handle the voltage since it was DCC ready. Track voltage measures at 12V AC. What are your thoughts?
Tedski
Do you have the headlight on? It's the turbogenerator. Unless your steamer is from before they used electric lights, it should have that sound.
Yes, I found out it was the dynamo. My problem is that when the light is on, so is the dynamo sound. When I turn off the headlight, the sound slowly goes away. I'd like to be able to have the headlight on or off without affecting the dynamo sound. Looking at the tsunami technical reference, I think I can program the CVs so that the sound is not tied to F0. That's what I'll try next. Although the dynamo sound is interesting because I didn't realize steamers had this, I can do without it and as a last resort may just turn off the CV that controls the sound for the dynamo. Keeping my fingers crossed. Experimentation is now delayed because of need to go with wife to the movies. Hopefully later tonight or tomorrow.
tedski
Ted
Or adjust the volume of it in the mixer so it is not so loud. Barely perceptible over the other sounds would be about right, they aren;t that loud unless you climb up right next to it, at least on any of the steamers I've ridden behind.