Is there anyone out there willing to share their secret(s) or skill(s) "How to make a N gauge speaker give better sound"? I'm new at this and I can see that positioning, securing and location can help make better or worse sound. Thanks for your time and sharing your experience(s).
The most important aspect for good sound is the speaker enclosure. It needs to be fully sealed, to get maximum "oomph" Check out the numerous threads here on ESU LokSound installations (by me and others) to see how we install. Position is less important, but I prefer having the speaker firing upwards, and use the shell as an extra baffle. With the modern "sugar cube" speakers, there seems to be no need for putting holes into the shells (nothing is that air tight).
The best speakers for N-scale use are rectangular cell-phone type speakers, that come in 8x12, 9x16, 11x15 and 13x18mm sizes. The 8x12 and 9x16 will fit in hood diesels; add the 11x15 for cab units, and the 13x18 is ideal for many steam tenders. Bare speakers in these sizes are available from the major electronics distributors (Digikey and Mouser). Look for Soberton and CUI as the manufacturers. As Rick notes, the key to best sound is a fully sealed enclosure around the speaker. But the enclosure also has to be of sufficient internal volume so that the air trapped inside can help extend and smooth the frequency response of the bare speaker. Manufacturers typically test their speakers in a 1 cubic cm (1000 cubic mm) enclosure, and I've found that this size is best for the 13x18mm speaker. Ignoring the depth of the speaker itself, this means that a 6mm-deep enclosure (not counting the thickness of the bottom) should work (13x18x6 = 1,404; subtract a bit for the depth of the speaker itself, and you've got something around 1000 cubic mm). For the 11x15 and 9x16, I find 750 cubic mm to be a sort of minimum for best sound; again, this counsels for an enclosure that is at least 6mm deep. For the 8x12, about 500 cubic mm seems the minimum, and again that's about a 6mm-deep enclosure. Note, however, that you do not have to build your enclosures as simple boxes. Say that you only have 5mm of depth to work with on your particular engine, and that the bottom of the enclosure will take .5mm, leaving 4.5mm of total depth. But you have 20mm of length to work with, and you want to use a 9x16 speaker. OK, make the sides of the enclosure 4.5mm, but make it 20mm long, offsetting the speaker to one side, and sealing the unused top with some styrene. 9x20x4.5 = 810. It might look a little weird, but it will work great. It doesn't matter what the shape of the enclosure is - rectangle, triangle, cone, whatever works (and if you know someone with a 3D printer, speaker enclosures are a perfect use for this technology). Rick also alludes to another debate, which is whether to have the speaker firing up, or firing down into the enclosure. In the latter case, the back wave of the speaker diaphragm is what you will be hearing, but it works - although some empirical evidence suggests that having the speaker firing up produces better sound. Sometimes, though, the "downfiring" approach is necessary for wiring purposes. Finally, note that no matter what you do, you aren't going to get any real bass sound with the tiny speakers we use. Even the 13x18 speakers don't go below 300hz - low midrange, but not really bass. 500hz is a common cutoff for useable frequency response. But if done right, even this lower midrange will give a decent illusion of a diesel prime mover, and the sound will "scale" appropriately to the small engine. Done well, sound in N scale can be the equivalent of factory-installed sound in HO scale engines. I have a friend down the road who has many factory-sound equipped HO engines, and nearly all of them sound appreciably worse than my custom installations in my N scale engines. We'll fix his in time John C.
