The thing that’s missing in large scale sound is bass frequencies–small speaker, small enclosure equals weak bass. It’s the law of physics. To improve bass response in small enclosures like bookshelf speakers or table radios, speaker designers generally go with a ported cabinet–a cabinet with a small hole in it. In the hole is typically a cardboard tube, say 1 inch in dia. x 2 in length. The port is usually “tuned” to emphasize certain frequencies, by adjusting the length and the diameter. There are standard parameters for doing this. But the basic principle is if you want small and loud with good bass response, you go with a ported speaker. I know this not as a speaker designer, but as a semi-pro bass player So large scale sound–you have small enclosures and small speakers. Why not port the enclosure? So I did–I recently installed a QSI soundcard in an Aristo Pacific. I put the speaker in the loco up by the smokebox, under the boiler shell, and then put a port in by drilling through the backhead and the back wall of the boiler shell. (I know, but I had already drilled a hole through the backhead for an aristo code set switch, so I just made it bigger.) Then I put a piece of scrap brass tube about 1/2 by 2 though the hole and hot glued it in place
"img> Here’s a sound comparison. For the first clip, I plugged up the hole with tape, so this is the sound with no port http://chnm.gmu.edu/courses/magic/westover/plugged.mp3 For the second clip, I opened the port http://chnm.gmu.edu/courses/magic/westover/ported.mp3 These are downsized mp3s, so some of the difference has been lost, but to my ears the ported cab is much much better. It’s hard to tell on small speakers and mp3, but it seems apparent to me. Try listening to it with a decent pair of headphones. If anyone is interested, I can post the full size .aiff file
