JohnActon posted:Lou, acoustic suspension speakers are sealed enclosures much like the small plastic cans most people use in toy trains. They are never as efficient as vented cabinets such as base reflex or transmission line enclosures. With this puny amp one really needs a vented design. I have not tried to build a BR or TL enclosure to fit inside a locomotive though I think one could fit inside an unpowered unit.
As was pointed out above, building speaker enclosures is a scientific endeavor. First off not all drivers will work in a ducted port, bass reflex, or transmission line box. Those designs require certain electrical and mechanical driver characteristics. The combination of which are listed as Qt on a spec list that shows the Thiele-Small parameters. That number has be below .65.
Secondly, designs that utilize the speakers back wave have to much larger than a close box design. To augment even a 100 hz wave that box has to have a chamber at least 25 feet long for a quarter wave to return in phase with the front wave.
Laws of physics are going to prevent a high fidelity system using a 2" or smaller driver. The speakers themselves are not capable of any real bass response and any enclosure that would enhance that response will not fit an any O scale piece of motive power or rolling stock.
Best bet is look for a driver with the greatest Sensitivity if greatest volume is your goal.
Pete
