I am puzzled as to how to physically mount a speaker to get all of the sound out of it.
Can someone expound on the best way to achieve the most sound for a given, 20 mm (3/4") speaker.
Air holes? Small holes? Big holes? Bulkhead mount? Solid mount? Loose mount? What works best?
A few more details would help with recommendations - for starters, what scale ??? N, HO, O, Large Scale ??? - & what type of loco are you installing it in (small early steam loco, large modern (late 1920's ~ 1940 era) steam loco, diesel) ??? MUCH easier to install a speaker in a Large Scale loco :D (in fact, most Bachmann large-scale locos have speaker mounting provisions built-in) than an N-scale model. ;)
Tom
Use the largest possible hole at the front of the speaker. If you use multiple holes, try to have a total area at least 50% of the area of the speaker (100% is better.)
Totally enclose the back of the speaker with an airtight chamber. This prevents the sound waves from the back of the speaker cancelling out the sound waves from the front of the speaker. The airtight chamber should be as large a volume at possible.
You have specified a 3/4" speaker. In general, the larger the speaker the better. If the width is restricted (usually the case in model railroad equipment) then use an oval speaker or multiple speakers wired together to get more area if you can.
Jim
I just noticed that you did give the speaker size at least (3/4" in), so I'm going to guess you're talking an HO loco. The more of the speaker cone area you can expose, the greater your sound output will be. For mounting, if the loco does not have built-in speaker mounting provisions, hot glue or silicone rubber applied carefully around the speaker perimeter should hold it in place. ;) I'll also second a lot of Jim's comments - but again, telling us what type of loco it's going in may also get you better info. 8) Tom
Sorry I forgot to include the scale.
HO.
Diesels in GP type locomotives which have VERY limited space.
Bachmann Spectrum GE 8-40 Conrail 6044 is the one that I'm working on right now. I found two open grill areas that 85% of the two 3/4" speakers cam be mounted inside facing out them. I have canopy glue (from RC airplanes) that is holding them in place. I used it because it dries clear (thus less of a obvious mess with the overflow of glue). Enclosures are going to be problematic though. Going to have to shave them as thin as possible in order to clear the flywheel weight.
Next (when money allows--VERY tight right now with the fuel oil bill and it being so cold) will be the three Bachmann Spectrum SD-45s. They will be the last of my "big" diesels.
Last will be my LifeLike RS-2 which has NO room inside it. I wonder if I take the fuel tank off, mill a round area in the weight, drill a milliion small holes in the fuel tank, put it all back together if that wouldn't work?
Any chance of getting an RS-2 dummy? Lots of room for a sound system in a second unit permanently attached to the powered unit.
Jim
I've backed myself into a corner with the RS-2 by making it my yard/switch engine. I haven't opened it up yet so I'm ASSUMING nothing as far as space inside it.
I took one of the SD-45's apart and it has enough room for a 3/4" speaker after I milled part of the weight down so I'm ASSUMING that the other two will need the same treatment to fit the speaker in.
I glued two 3/4" (soldered them in parallel) speakers into the GE 8-40 and it sound great.
Thanks to all for the replies. It's been an adventure.
Are you listening Bachmann, we need dummy units. If you are trying to put a sound decoder into a h.o. or n scale its like trying to put a ten pound bag of ,well you know. Please make dummy units.
Quote from: rustycoupler on February 09, 2010, 11:51:42 PM
Are you listening Bachmann, we need dummy units. If you are trying to put a sound decoder into a h.o. or n scale its like trying to put a ten pound bag of ,well you know. Please make dummy units.
It's not hard to make your own dummy units, either take the motors out or buy Athearn (or any other companies') dummies. They do not even need to be the same locos.