Digitrax SP282832 | Round 28mm 32 Ohm Speaker | HO Scale

The Digitrax SP282832 is a 28mm round speaker in the 32 ohm version, for sound decoders whose amplifier expects a 32 ohm load. It is the same full-size cone as the 8 ohm SP28288 - the extra diaphragm area gives HO and larger locomotives real low-end punch - and it ships with interface wires already attached.

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• 32 ohm impedance for decoders that specify a 32 ohm speaker. Fitting an 8 ohm speaker to a 32 ohm output is the most common cause of distorted or quiet sound.
• 28mm round cone moves far more air than 13mm or oval speakers - the usual pick for HO diesel hoods, boilers and tenders.
• Interface wires pre-attached - nothing to solder at the speaker end.
• Baffle or enclosure strongly recommended. A sealed box is the difference between thin and convincing.
• Needs roughly 1-1/8 in. of clear width plus depth for the baffle, so check the shell before ordering.

How do I know if I need 32 ohm or 8 ohm?
Your decoder manual states the rated speaker impedance. Use this 32 ohm speaker only where the decoder calls for 32 ohms. If it calls for 8 ohms, use the Digitrax SP28288 instead - same speaker, 8 ohm version.

What happens if I use the wrong impedance?
Too high an impedance gives quiet, thin sound. Too low draws more current than the decoder amplifier is rated for and can overheat or damage it. Matching the decoder spec is always the safe route.

Will a 28mm speaker fit my locomotive?
It needs about 1-1/8 in. of clear width plus room for a baffle - fine in most HO diesels, large steam tenders, and anything O or G. For N scale or a tight boiler, use the 13mm SP13138 or oval SP10188.

Do I need an enclosure?
Strongly recommended. Without one the rear wave cancels the front wave and you lose the bass entirely. Even a simple sealed styrene box makes a clear difference.