Quick Help - Connecting Speakers
Zimo sound decoders provide 2 purple wires for connection of a speaker. Recommended speakers are normally 8ohm and 1W, but the MX644 and MX645 can power up to 3W and down to 4ohm. The large scale decoders can handle much more - usually 10W at 8ohm.
For the decoder models that can handle 4ohm, you can connect a pair of 8ohm speakers in parallel which results in the overall impedence being 4ohm, but with the power added together e.g. 2x 1W/8ohm speakers in parallel results in 2W/4ohm overall.
When connecting just a single speaker, the polarity is not important, but with 2 speakers in parallel, you need to match same sides (it won't cause any damage if you get it wrong, but it may result in the sound waves from one speaker cancelling the other one out! Using 2 different types of speakers is unlikely to suffer this noise-cancelling effect, but in theory you could get it there too.
A wide variety of shapes and sizes of speaker are available, and for most types, how to connect them properly is fairly obvious - they either provide wires already, or have a pair of solder tabs. However, many of the cube-style speakers are less obvious and need to be connected with some extra care, especially since they normally have a metal back-plate which you must be careful not to bridge solder/wire onto, or you'll get an instant short circuit and most likely damage the decoder's amplifier circuit.
There are 2 types of connection for cube speakers - those with spring clips and those with solder pads. Many of the YouChoos speakers provide solder pads, which we prefer because they give a neater finish and allow the speaker to sit flatter if you put the connection side down. Trim about 1mm of the speaker wire end, pre-tin, and solder to the speaker. The less bare wire you leave, the better.
It is recommended that you solder even the spring-clip versions, as just inserting bare wire ends into the clips is not very secure. Tin the clip, strip 2-to-3 mm off the speaker wire end, pre-tin, and solder to the outside of the clip - this reduces the risk of shorting onto the back-plate of the speaker.
When mounting cube speakers, there is no 'up' or 'down' - the box is the resonator itself - so choose the most convenient way up to mount. Curve-top versions have an obvious way up of course! If you have the metal back-plate side toward the model's chassis, then you must insulate the place where you will seat it with some electrical tape, or similar. It is common to use BlackTack or a double-sided tape too, but just ensure that there is no way that any metal part of the speaker can come into contact with anything else metal, or it will be curtains for your sound decoder's amplifier circuit!