Here's my thoughts based on experience and experimentation.
I've made enclosures from plastic, wood and lead. The wood enclosures sound the best, even though lead has a zero resonant factor. On average, the plastic enclosures that come with speakers should have about twice the volume they do for optimum efficiency of the speaker. I beleve they are made "too small" in order to fit the largest speaker in the smallest space.
I've netted way better results using a slightly smaller speaker with a bigger enclosure in the same given space.
Lastly, round speakers are way more efficient than rectangular versions. The cone movement is equal across the surface of a round speaker. With a rectangular speaker, the cone movement is restricted to the amount given by the narrow side. Two 16mm round speakers will give better sound reproduction than a single 16mm X 34mm speaker in a like sized enclosure.
That's been MY findings based on a lot of experimenting.
Now .... how about them wheel wipers ? ....
Mark.
¡ uʍop ǝpısdn sı ǝɹnʇɐuƃıs ʎɯ 'dlǝɥ
O.K., wood it is! This fits with my supplies, I have lots of wood and like working with it. What can you tell me about installing the speaker: Should it be held loosely in the enclosure or secured somehow? How much room should be allowed around and on top of the speaker? The tender shell in this case is plastic with a plastic chassis underside. There is a lead weight I will reinstall, after I see if I have enough room for it.
Mike, are you o.k. with this small trip into speakers? as I can surly start a thread on this?
NP 2626 "Northern Pacific, really terrific"
Northern Pacific Railway Historical Association: http://www.nprha.org/
Mark,
I'm totally OK with speaker stuff.
The speaker should be held tightly, with some form of gasket or sealant to ensure no leaks. If you use Soundtraxx speakers, I think they even make nice little sticky gaskets that fit for this purpose. Others may have them too.
Here's the link to what's available from Soundtraxx:
http://www.soundtraxx.com/access/baffles.php
Mike Lehman
Urbana, IL
BTW, I just posted some pics of the speaker and enclosure I built in the tender of my K-36 in a thread Rich started asking a similar question about enclosures.
http://cs.trains.com/mrr/f/744/p/243590/2712970.aspx#2712970
Post moved to the thread on speaker placement in this forum, which is more probably where it should be.
There are various formulas for this, but the basics are usually enough given the size of these things. I think most people go for twice the volume required to enclose the speaker. Someone else will probably have better terminology, my CRS is not helping right now.
The Soundtraxx premade enclosures are an example. The simplest is just the bottom ring that the speaker attaches to and a back to seal it up. That bottom ring is just tall enough to clear the back of the speaker and wide enough for the speaker to set in (plus seals around the rim better.) You get three more rings IIRC that allow you to increase enclosure volume. One extra ring added, i.e. ~doubling the volume, gives pretty good performance.
So measure you speaker then douible the size of the box that wiuld enc;lose them and you should be close. Obviously, sometimes don't fit that way, so you have to settle for less than ideal.
Thanks Mike, I didn't expect to see an answer here, after I moved my question to Rich's thread on where to put speakers.
I can see installing the speakers under the tender's coal load maybe being a better orientation of the speaker, for sound. Do you and others who have done so, feel this to be true?
Most of the time, I have never thought the plastic coal load molded into the tender, to look much like real coal and have added Woodland Scenic’s coal to make the load look better. The coal is glued into the tender using the same method I use for securing ballast and other scenic elements. I can see this being a problem with having the speaker pointed up through the coal. Certainly, you would want to glue the coal down, previous to installing the speaker. Has anyone tried this out? What did you do and how did you do it?
Theoretically, I'd say upward firing through the coal laod, whatever it is, would reproduce high freq sound better, BUT...
Blackstone uses a solid coal load, with the underframe having openings beneath to allow the sound out by downward firing. My Blackstones all sound great, so I suspect in real life it makes no discernable difference with a good install that's properly enclosed.
I have thought of spraying the foam "coal" loads I made with 3M 77 adhesive and rolling them in coal. However, that tends to be messy and shed. It would probably work and look good as far as covering the speaker, so is probably worth experimenting with. Not enough difference to make it worth the potential messiness for me. The foam by itself looks pretty darn good.
375 also has one of these "coal" loads and it looks pretty good at 3'.