Finding the low notes

Check the archives ... Rayman4449 had an arrangement where he turned the better part of a tender into a bass tube for some of his engines..... and remember you can get a lot bigger than 1" worth of speaker into most large scale engines! The trick is usually to seal up the enclosure well, and insulate around the box.

Additionally, you might try your "stationary" sound system with a microphone so that passing trains would make the area they were in "rumble" as they passed.... I've considered using an old reverb unit in a tunnel in much the same way (would also work for folks deciding to shout down the tunnel to see if they got an echo....)

Mostly, I'd take a look at some computer and personal music appliance approaches to delivering full spectrum music from small enclosures, and either imitate or borrow from that group, so you could keep the sound all "on board."

Matthew (OV)

On another forum I posted the results of my experiment with "porting" the enclosure. I'm a semi-pro bass player, and while I'm not a speaker designer I have a lot of experience with speaker cabs. If you want good bass response and efficiency in a small enclosure, your best bet is to port the enclosure. Nearly all small bookshelf sized speakers are ported for exactly this reason.
I put a Phoenix sound speaker in the boiler of an aristo Pacific, and then drilled a hole in the backhead and inserted a brass tube as a port.


You can hear the result in these two files
First, unported

http://chnm.gmu.edu/courses/magic/westover/plugged.aif


Second, with the port installed

http://chnm.gmu.edu/courses/magic/westover/ported.aif

Speaker design/porting is a science, and to really do it right you need the specs of the speaker and the interior volume of the enclosure. But my guestimate produced noticeably better bass response, which you can especially hear in the above samples if you have decent headphones or run the sound into decent speakers

This would be extremely easy to do in a steam engine tender--the port is just a tube made of cardboard or PVC or whatever, and it can face down

On a side note, this is probably the worst forum software I've ever used. It took me 20 minutes to post this and I still can't get the sound fiels to show up as clickable links. Sorry!

Long story shortened?: I have had an experience that may tell you something, but don't try (risk)it. I also am into sound systems and noted the lack of realistic rumble. I heard a Dallee system in a sd45 at the ECLSTS a few years back and thought it sounded good. I bought and installed it. It did not impress me. It sounded off. I have the 22w amp upgrade and no matter how I adjusted the volume it sounded distorted. I fried the original speaker just sounding the horn. I tried three different speakers, but the enclosure suffers (sd40 fuel tank w/ back opened through shell).
While going through this my G gauge MTH Challenger was sounding distorted. It later toasted the onboard amp.
I had hooked up a forth speaker to the dallee and thought I'd try it with the MTH. It was 8 ohms. The stock MTH says 4 ohms. It's a small KLH 911B home surround speaker. I put it on a flat car and when I hooked up the challenger, WOW!!! The frequency range, and the clarity, never heard any toy train sound so good. That MTH sounded digitally perfect thru all the frequencies. Then... the board's amp fried. Oh (shoot). Was it going anyway??
The enclosure made the difference. Well I had the best bass response I ever heard for those fleeting seconds...... It's fixed now and I don't have the kahunas to ever try it again. I have bought better QSI high bass speakers but they don't match that KLH, and I'm a JBL nut, or infinity, or polk, or.... You should have heard it. Maybe I'll add trucks, Joe