Bass reflex speakers.
(Old part number: DCCS03-08)

8 Ohm, 2 watt. 18mm x 52mm x 14mm.
N.B. Price is for One speaker only.

This is our new 'American' style speaker, specifically designed to fit the narrower hood of US locomotives. It is also equally useful in any narrow space, such as a steam locomotives boiler, or a shunting loco.
Although this is a smaller unit than our full size speakers, we've sacrificed none of the performance our speakers are famed for the same low frequency rumble, and more rounded overall sound output is present. We've added another watt, so these little speakers are ready to handle the next generation of sound decoders.

The fitting lugs can be removed with a razor saw, or used with the integral isolation grommet to screw fit the speaker in place.

Bass Reflex, Technical theory of operation.
In contrast to placing a chamber on the back of the speaker which is (almost) air tight, a bass reflex system has a port or vent engineering into the case, which consists of an opening, generally backed with a pipe or duct of circular or rectangular cross section. The air mass in this opening resonates with the "springyness" of the air inside the enclosure in exactly the same fashion as air in a bottle produces a low frequency sound when a current of air is directed across the opening (try it, it's fun!). The frequency at which the box/port system resonates, known as the is determined by the cross sectional area and length of the duct and the volume of air inside the enclosure.

This permits a lower frequency sound to be produced by a smaller speaker than could otherwise do so. The design type augments the bass response of the speaker, and can extend the frequency response of the speaker/enclosure combination to below the range the speaker would reproduce in a sealed box. The enclosure resonance has a secondary benefit in that it limits cone movement in a band of frequencies centred around the tuned frequency, reducing distortion in that frequency range.